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May 06, 1998 Work Session
CITY OF COLUMBIA HEIGHTS ..... , Councilrnembers 590 40TH AVENUE N.E[., COLUMBIA HEIGHTS, MN 55421-3878 (6 ! 2) 782-2800 TDD 7~2-2806Do-Md (7. Jolly Marlaine Szurek Gary L. Peterson Robert W. Ruettimann City Manager Wah Fehst ADMINISTRATION NOTICE OF COUNCIL WORK SESSION Meeting of' Date of Meeting: Time of Meeting: Location of Meeting: 2. 3. 4. 5. 6. 7. Notice is hereby given that a Council Work Session is to be held in the CITY OF COLUMBIA HEIGHTS as follows: ~NFERENCE ROOM Authortzatton to Request ,p 95 ' ' Pro osals or Recod~cation and Publication of the Ci~ Code Consideration of Adj~tment to Sala~ Range for Position of Assistant Finance Director ~~ I Status Report- Hard SuOce Driveway/Par~'ng Spaces ~g.~., g: s e ~.¢..11 t Project SafeW Net Bill for1998,, ~ Social Securi~ Issue for Volunteer Firefighters ~)~;~~:, ~ .~ -.'-.-~'~'~ . The City of Columbia Heights does not discriminate on the basis of disability in the admission or access to, or treatment or employment in, its services, programs, or activities. Upon request, accommodation will be provided to allow individuals with disabilities to participate in all City of Columbia Heights'services, programs, and activities. Auxiliary aids for handicapped persons are available upon request when the request is made at least 96 hours in advance. Please call the City Council Secretary at 782-2800, Extension 209, To make arrangements. (TDD/782-2806 for deaf only) THE CITY OF COLUMBIA HEIGHTS DOES NOT DISCRIMINATE ON THE BASIS OF DISABILITY IN EMPLOYMENT OR THE PROVISION OF SERVICES EQUAL OPPORTUNITY EMPLOYER CITY OF COLUMBIA HEIGHTS Joseph Sturdevant Councilmembers 590 40TH AVENUE N.E., COLUMBia HEIGHTS, MN 55421-3878 (612) 782-2800 TDD 782-2806Donald G. Jolly Marlaine Szurck Gary L. Peterson Robert W. Ruettimann City Manager Walt Fehst ADMINISTRATION NOTICE OF COUNCIL WORK SESSION Notice is hereby given that a Council Work Session is to be held in the CITY OF COLUMBIA HEIGHTS as follows: Meeting of: CITY COUNCIL~CITY STAFF Date of Meeting: WEDNESDAY, MAY 6, 1998 Time of Meeting: 7:00 P.M. Location of Meeting: CITY HALL CONFERENCE ROOM 2. 3. 4. 5. 6. 7. Authorization to Request Proposals for Recodification and Publication of the City Code Consideration of Adjustment to Salary Range for Position of Assistant Finance Director Payment for Emergency Repair of Sanitary Sewer at 4120 and 4121 Second Street Feasibility Report on Storm Water Improvements from Bonestroo Status Report - Hard Surface Driveway/Parking Spaces Project Safety Net Bill for 1998 Social Security Issue for Volunteer Firefighters The CiO, of Columbia Heights does not discriminate on the basis of disability in the admission or access to, or treatment or employment in, its services, programs, or activities. Upon request, accommodation will be provided to allow individuals with disabilities to participate in all City of Columbia Heights'services, programs, and activities. Auxiliary aids for handicapped persons are available upon request when the request is made at least 96 hours in advance. Please call the City Council Secretary at 782-2800, Extension 209, To make arrangements. (TDD/782-2806 for deaf only) THE CITY OF COLUMBIA HEIGHTS DOES NOT DISCRIMINATE ON THE BASIS OF DISABILITY IN EMPLOYMENT OR THE PROVISION Of SERVICES EQUal OPPORTUNITY EMPLOYEr CITY OF COLUMBIA HEIGHTS Meeting of: May 11, 1998 AGENDA SECTION: CONSENT ITEM ORIGINATING DEPT.: CITY MANAGER NO: 4 CITY MANAGER'S APPROVAL PROPOSALS FOR RECODIFCATION OF CITY CODE DATE: MAY 1, 1998 NO: The City Code was last codified in 1977. Since then, over 500 ordinances have been adopted by the City Council, which were to be incorporated into the code. This has not occurred on a consistent basis. That, along with the fact that the code should be reviewed and potentially revised to make it more clear cut and concise, incorporate modem and proper phraseology, and eliminate conflicts, ambiguities and repetitive provisions, results in the need for the recodification of the City Code. The recodification of the City Code has been a goal in the City's strategic plan since its adoption in 1995. Monies have been budgeted in 1998 to undertake this process. Staff is requesting authorization to seek proposals for recodification and publication of the City Code. RECOMMENDED MOTION: Move to authorize staffto request proposals for the recodification and publication of the City Code. LLM/sh COUNCIL ACTION: Ci.ty of Columbia Heights Public Works Department Work Session Discussion Item Work session date: May 6, 1998 n. ,r,o¢~x~ Prepared by: Kevin Hansen, Public Works Director/City Engi Item: Payment for Emergency Repair of Sanitary Sewer at 4120 and 4121 2"a St. Background: The Sewer and Water Department was contacted by the owner's son of the property at 4121 2nd Street when it appeared that the service line had a structural failure and would have to be excavated. He was given a copy of the Ordinance and told that it would be the property owner's responsibility to pay for the repairs to the building service. PipeRight Plumbing excavated behind the curb to locate the pipe and confirm that the problem was in the street. Upon excavating in the street, it was discovered that the building services for 4121 and 4120 2nd Street were connected to the same riser and the riser was broken somewhere between the wye connection and the City's 18" trunk sewer line that is approximately 31' deep. The owner of 4120 2nd Street was not having any problems with her service as the property sits at a higher elevation and her sewage runs into 4121 2nd Street. Analysis/Conclusions: A conference was held between the Public Works Director, the Public Works Superintendent and the Sewer and Water Foreman. It was agreed that this repair had evolved into an emergency repair and that the work should be completed as soon as possible as the structural failure may have been a result of original construction design and material placement. The plumber was instructed to dig down to the main, separate the services and make the necessary repairs. A detailed summary of the events is attached. This item was pulled from the 4/27/98 Consent Agenda to further review the City's existing policy and review past similar events. Recommended Motion: Move to approve payment to PipeRight Plumbing in the mount of $9,978.22 for the emergency repair of sanitary sewer at 4120 and 4121 2nd Street with funds to be appropriated from the Sewer Fund (602-49450-4000). Attachment: Detailed summary of events CITY OF COLUMBIA HEIGHTS Public Works Department TO: FROM: SUBJECT: DATE: KEVIN HANSEN PUBLIC WORKS DIRECTOR/CITY ENGINEER LAUREN McCLANAHAN PUBLIC WORKS SUPERINTENDENT RECONSTRUCTION OF PRIVATE SANITARY SEWER SERVICE AT 4120 2~ STREET AND 4121 2~ STREET APRIL 20, 1998 Ordinance 4.326(8) Maintenance of Services states "The owner shall be responsible for maintenance of the building service, including cleaning, repair and replacement. All other city requirements shall be met in the maintenance of building services". The son of the owner of 4121 2nd Street, acting in his father's behalf, stopped in to see me when it was apparent that the service line had a structural failure and would have to be excavated. I read him the ordinance and reaffirmed that it would be the property owner's responsibility to pay for the repairs to the building service. The plumber, Pipe Right Plumbing, acted responsibly and excavated behind the curb to locate the pipe and make sure that the problem was in the street. The homeowner and the plumber hoped that the problem would be where the lateral service line connected to the riser. The plumber excavated in the street and discovered that the building services for 4121 and 4120 were connected to the same riser and that the riser was broken somewhere between the Y connection and the City's 18" trunk sewer line that is approximately 31' deep. The owner of 4120 2nd Street was not having any problems with her service because her property sits at a higher elevation and her sewage was running into 4121 2nd Street. It was at this stage of the excavation that a conference was held between Lauren McClanahan, Superintendent of Public Works, Kevin Hansen, Director of Public Works and Terry Randall, Utility Foreman. We agreed that this repair had evolved into an emergency repair and that the work should be completed as.soon as possible. We felt that the structural failure may have been a result of original construction design and material placement. Memorandum to Kevin Hansen April 20, 1998 Page 2 The plumber was instructed to dig down to the main, separate the services and make the necessary repairs. The repair was made by installing a cast iron riser and reconnecting the lateral service lines. The total bill is $10,478.72. The owner of 4121 2nd Street paid $500.00 down. SUMMARY The failed pipe was 31' deep. This is about 4 times deeper than average. The riser is shared by 4121 and 4120 2nd St. This was an emergency repair. Two homes were without sanitary sewer service. Due to the unique circumstances surrounding this repair, it is my recommendation that the City pay for this repair. I also recommend that the current ordinance be reviewed and perhaps modified to address extreme situations. LMcC:jb 98-135 Ci.ty of Columbia Heights Public Works Department Work Session Discussion Item Work session date: May 6, 1998 i~ Prepared by: Kevin Hansen, Public Works Director/City Eng Item: Bonestroo Report ~ Presentation of Storm Water Feasibility Reports Background: As a result of surface water runoff from a series of storms during July 1997, several areas throughout the City of Columbia Heights experienced short term flooding. To analyze the problem area and prepare engineering reports describing solutions and cost analyses, the City Council authorized entering into a contract with the consulting engineering firm of Bonestroo, Rosene and Anderlik (BRA) at their October 13, 1997 meeting. Discussion: BRA's tasks include data collection, data analysis/additional data gathering, hydrologic modeling, develop recommended improvements and prepare and present fmal engineering report. Representatives from BRA will present engineering reports for the following areas: Corporate Limit area Jackson Pond System (and area) 40th Avenue and McKinley Street Monroe Street NE and 49 ½ Avenue NE A copy of each report is attached. Other areas identified in the scoping study were deemed to be more local in nature and may be addressed directly in the design phase. After discussion and input from City Council, final feasibility reports will be submitted for approval. The next course of action will be project selection, design and construction implementation phase, and developing a financing plan. Requested Action: Discussion and input for engineering reports. Revised reports should then be formally accepted by the Council at a regular meeting. Attachment: BRA Engineering Reports F:\wp51 \worksess\brassfr Bon stroo Rosene Anderlik & Associates Engineers & Architects Bonestroo, l?osene, Anderlik and Associates, Inc. is an Affirmative Action/Equal Opportunity E~nployer Principals: Otto G. Bonestroo, RE. · Joseph C, Andedik, P.E.. Marvin L. $orvala, RE. · Richard E. Turner, RE. · Glenn R. Cook, RE.. Robert G. Schunicht, RE. · Je~'ry A, Bourdon, RE. - Robert ~X/. Rosene, RE. and Susan M. Eberlin, C.RA., Senior Consuitants Associate Principals: Howard A. Sant'ord, RE. - Keith A. Gordon, RE. · Robert R. Pfeffede, RE. · Richard ~A Foster, RE. · David O. LosRota, RE. · Robert C. Russek, A,I,A, · Mark A. Nanson, RE. · Michael T. Rautmann, RE. · Ted K.Fie]d, RE. · ~enneth R Anderson, RE. · Mark R. Roils, RE. · Sidney R 'Williamson, PaE., E.S. - Robert F. KotsrnJth · Agnes M, Ring, Michael R Rau, RE, · Allan Rick Schmidt, RE. Offices: St, Paul, Rochester, ~(/illmar and St. CIQud, MN · Milwaukee, ~'1 V~/ebsite: www. bonestroo.com DRAFT FEASIBILITY STUDY FOR STORMWATER IMPROVEMENTS CORPORATE LIMIT AREA COLUMBIA HEIGHTS, MINNESOTA BRAA FILE NO. 33210 This report presents the results of our stormwater improvements feasibility study for the Corporate Limit area. The Corporate Limit flooding occurred in July of 1997 along the Fridley/Columbia Heights border south of 52nd Avenue. We have completed our analysis of this area according to the plan detailed in our scoping study addendum of 12/18/97. This report begins with an introduction to the problem area followed in sequence by the following sections: Analysis and Results, Alternatives, Cost Estimates, and the Recommended Alternative. A location map and report figure are at the end of this report. Please note that elevations are in the city of Minneapolis datum followed in parenthesis by the USGS datum. The USGS datum is obtained from the Minneapolis datum by adding 710.3 feet. 1. INTRODUCTION A chronic backyard flooding problem has existed at 1280 and 1298 52nd Avenue in the City of Fridley- along Fridley's border with Columbia Heights (see figure 1). These homes suffered flooding as a result of the July 1, 1997 storm. The home at 1280 52nd Avenue also had flooding during the July 11 storm. Recently, the two cities cooperatively placed an additional 36-inch pipe above the existing 36-inch storm sewer in this area. At its upstream end, this newer pipe connects to a 100-foot section of 36-inch corrugated steel slotted drainpipe. The two 36-inch pipes discharge to a single 24-inch pipe (see Figure 2). 2335 West Highway 36 · St. Paul, MN 55113 · 612-636-4600 - Fax: 612-636-1311 During the July storms, residents witnessed stormwater discharging at high pressure from the backyard catch basins. This discharge, combined with overflow from two catch basins on Polk Place, caused flooding in these backyards. 2. ANALYSIS AND RESULTS We analyzed the pipe network upstream and downstream of the flood prone area. Additionally, we located and characterized sources of overland flow such as the overflow from the catch basins at the intersection of Polk Place and Pierce Terrace. Anecdotal evidence obtained from resident interviews and water staining on the two homes suggest a July 1 high water level (HWL) of 234.1' (944.4'). The tipping bucket rain gauge at the public works facility indicated that the July 1 storm was the most intense of the three July storms, with over 3.64 inches of rain in 3.5 hours and 2.9 inches in the first hour. Our model, developed with the XP-SWMM32 software, .simulated the July 1 storm and supports the anecdotal evidence obtained from residents at 1280 and 1298 52nd Avenue. As mentioned above, water staining suggests a HWL of approximately 234.1' (944.4') for the July 1 storm. The two homes are both walkouts. The Iow openings for 1280 and 1298 52"d Avenue are 233.4' (943.7') and 233.9' (944.2'), respectively. Our model calculated a July 1 HWL of 233.9 (944.2'), which calibrates well with the observed HWL. 3. ALTERNATIVES Various alternatives were considered to address the flooding problem. Of these, four were studied in detail and are presented in this report. 3.1 Alternative 1' Berming in the Vicinity of 1280 and 1298 52nd Avenue NE. Alternative 1 involves constructing a berm to protect the homes at 1280 and 1298 52nd Avenue NE (see Figure 2). For this alternative, excavation and embankment should balance. If berm construction results in a net loss of storage, then the HWL for a given storm will rise. The berm top should rise to 234.9' (945.2'), which is approximately 1 foot above the calculated 100-year, 24-hour storm and July 1 HWLs. Since storage below 233.9' (944.2') must remain the same, some excavation will occur across the corporate boundary into Columbia Heights where several trees from 8 to 24 inches in diameter now grow. These would likely have to be removed. Additionally, the berm will tie in to high ground one lot to the east and west of 1280 and 1298 52nd Avenue NE, necessitating disturbance of property that has not experienced flooding. Drainage of areas isolated behind the berms would require sump pumps. 3.2 Alternative 2: Emergency overflow grading This alternative consists of grading an emergency overflow (EOF) below the current overflow elevation of 234.7' (945.0') so that 100-year protection is afforded the homes at 1280 and 1298 52nd Avenue NE. Overflow would flow down the current drainage easement to the Iow area off Polk Circle. From this low area, the flow enters the 36-inch trunk via two ditch type catch basins. This alternative includes clearing and grubbing within the existing city drainage easement so that disruptions to this flow are minimized. In addition to clearing and grubbing, landscape features, sheds, and woodpiles would also require removal. We recommend an EOF elevation of 232.4' (942.7'). Table I summarizes the effect this grading will have on the area around 1280 and 1298 52nd Avenue and as well as the Iow area off Polk Circle. There are several potentially adverse impacts to this alternative. There will be no defined flow path, so runoff may flow through or pond in backyards. There is a significant potential for erosion. Runoff may begin to cut a ravine, which could continue to erode and grow over time. This would cause sediment build-up in the downstream low area and potential clogging of the catch basins there. Table 1 High Water Levels, Alternative 2 Polk Circle 1280 & 1298 52nd Low HWL Freeboard Low HWL Freeboard Storm house House (city (city (city (city datum) datum) (ft) datum) datum) (ft) Before EOF July 1 207.3 1.4 233.9 -0.5 grading 208.7 233.4 After July 1 207.7 1.0 233.3 0.1 EOF grading 100-year 206.6 2.1 233.2 0.2 For the 100-year event, we calculate a peak flow of 27 cfs over the EOF and mean channel velocity of 6 feet per second (fps) to the downstream ponding area off Polk Circle. 3.3 Alternative 3: Overflow with standard pipe installation This alternative consists Df approximately 600 feet of 18-inch reinforced concrete pipe (RCP), installed by open cut trenching to the ponding area east of Polk Circle (see Figure 2). This pipe would be laid adjacent to the existing pipe and would discharge directly to the ponding area. This ponded stormwater would enter the trunk system through the beehive catch basins located at this Iow point. The existing overflow elevation would be lowered from 234.7' (945.0') to 232.4' (942.7'). This overflow would operate for storms in excess of the 10-year, 24-hour event. Grading would occur in the existing drainageway in conjunction with the pipe installation so that a clearly defined overflow route is created. Numerous trees, fences, sheds, and landscaping make this a politically sensitive alternative and create a large restoration cost. 3.4 Alternative 4: Overflow with directional bore pipe installation This alternative involves directional boring of a 20-inch (outside diameter) high density polyethylene pipe and is considered if resident resistance precludes open trench installation. As with alternative 3, this construction involves grading of an emergency overflow (EOF) at 232.4' (942.7'). Stormwater would overflow for storms greater than the 10- year event. Unlike alternative 3, no improvement of the drainage path beyond the limits of the EOF grading is proposed, so as to minimize disturbance of the area. This may result in maintenance problems in years when the EOF is topped (see discussion under Alternative 2). These long-term costs were not considered in the cost estimate for this alternative. Alternatives 3 and 4 are identical from a hydraulic perspective. Both require nd sufficient catch basin capacity near 1280 and 1298 52 Avenue NE so that 20 cfs passes into the pipe under approximately 1.2 feet of head. We propose 2 catch basins with rim elevations of 942.0'. These should be covered by stool type ditch grates similar to Neenah R-4342. These have a relatively Iow profile, which would be more appropriate for installation in private backyards. Each grate should pass approximately 9 cfs under 1.2 feet of head. In considering alternatives 2, 3 and 4, it should be understood that passing water more quickly out of this area has the potential to flood the downstream ponding area if the catch basins there become clogged with debris. It has been indicated that water came within 5 feet (horizontally) of a home off Polk Circle. The corners of this home lie at approximately 208.7' (919.0') and 5 feet from this would suggest a July 1 HWL of 208.2 (918.5'). Our model predicts a July 1 HWL of 207.1' (917.4)' for this area and, after alternatives 3 and 4 described above, a July 1 HWL of 207.5 (9t7.8'). This discrepancy suggests that the catch basins did not drain the ponding area to their full capacity and that they might have been clogged. Table 2 summarizes the effects of the improvements proposed under Alternatives 3 and 4. Table 3 shows the effect these have on the downstream ponding area. The results are derived from the XP-SWMM32 model of the area. 4 Table 2 Flows and High water Levels, Alternatives 3 and 4 Freeboard Flow in Overflow HWL Storm proposed pipe Overflow Elevation (city datum) (ft) (cfs) (cfs) (city datum) Before Improvements July 1 233.9 -0.5 NA NA 234.7 July 1 232.9 0.5 22 21 100-yr 232.9 0.6 20 18 (6.0") After 50-yr 232.7 0.7 18 9 Improvements (5.3") 232.4 25-yr 232.6 0.8 15 3.5 (4.7") 10-yr 232.4 1.0 10 0 (4.1") Table 3 High Water Levels in Downstream Ponding Area Alternatives 3 and 4 HWL Low House Freeboard Storm (city datum) (city datum) (ft) Before Improvements July 1 207.3 1.4 After 208.7 Improvements July 1 207.5 1.2 4. COST ESTIMATES · Cost estimates are provided for all three alternatives. 4.1 Alternative 1 Cost Estimate Table 4 presents the cost estimate for Alternative 1, berming in the vicinity of 1280 and 1298 52nd Avenue NE. Table 4 Estimated Cost: Alternative 1 Item Unit Quantity Unit Price Cost Mobilization Clearing and grubbing Excavation and embankment Sod Trees Sump pumps, PVC pipin~ LS I $600 $600 LS 1 2,000 2,000 CY 150 10.00 1,500 SY 650 5.00 3,250 EA 15 200 3,000 EA 2 500 1,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $11,350 567 $11,917 2,383 $14,300 715 $15,o15 4.2 Alternative 2 Cost Estimate Table 5 presents the cost estimate for alternative 2, emergency overflow grading. Table 5 Estimated Cost: Alternative 2 Item Unit Quantity Unit COst Price Mobilization LS 1 $600 $600 Clearing and grubbing LS 1 4,000 4,000 Excavation and embankment CY 270 10.00 2,700 Sod SY 800 5.00 4,000 Trees EA 6 200 1,200 Estimated Construction Cost 5% Contingencies $12,500 625 $13,125 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST 2,625 $15,750 787 $16,537 4.3 Alternative 3 Cost Estimate Table 6 presents the cost estimate for Alternative 3, overflow with standard pipe installation. Easement acquisition costs are approximate. Table 6 Estimated Cost: Alternative 3 Item Unit Quantity Unit Price Cost Mobilization 18-inch RCP, some overdepth 18-inch FES Clearing and grubbing Common excavation, channel shaping Sod Trees CB-MH 2'x3' 4' Diameter MH Easement acquisition, temporary LS I $5,000 $5,000 LF 660 30.00 19,800 EA I 1,000 1,000. LS I 5,000 5,000 CY 520 7.00 3,640 SY 4200 3.00 12,600 EA 45 200 9,000 EA 2 1,000 2,000 EA I 1250 1,250 AC 0.5 20,000 10,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $69,290 3,465 $72,755 14,551 $87,306 4,365' $91,671 4.4 Alternative 4 Cost Estimate Table 7 presents the cost estimate for alternative 4, overflow with directional bore pipe installation. Easement acquisition costs are approximate. Table 7 Estimated Cost: Alternative 4 item Unit Quantity Unit Price Cost Mobilization LS I $6,000 20-inch OD HDPE, some overdepth LF 630 140 $6,000 88,200 18-inch RCP Clearing and grubbing Common excavation, EOF shaping Sod Trees CB-MH 2'x3' Easement acquisition, tempOrary LF 30 30 LS 1 2,500 CY 140 7.00 SY 1400 3.00 EA 15 200 EA 3 1,000 AC 0.5 20,000 9OO 2,500 98O 4,200 3,000 3,000 10,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $118,780 5,939 $124,719 24,944 $149,663 7,483 $157,146 5. RECOMMENDED ALTERNATIVE We recommend alternative 1. This approach provides I foot of freeboard and costs significantly less than the alternatives 3 and 4. In addition, it has the advantage Of not passing additional flow to the downstream ponding area. These additional flows combined with the potential for channel erosion argue against alternative 2. Although the model shows adequate freeboard for the home adjacent to the downstream ponding area (even after alternative 2, 3 and 4 improvements), and shows a delayed peak from the overflow down to this area, anecdotal evidence suggests that water levels were higher than those calculated by the model. This may be due to catch basin clogging, but is of enough concern to warrant caution. Although alternative 2 has a relatively Iow cost, we do not recommend it due to the potential for significant erosion. Further study of the flow path downstream of the emergency overflow is required, and a swale or channel design likely would be warranted. This drainage work would add to the cost and disruption associated with this alternative. 0 C) 0 -< 0 II 0 ~o -.-..I__z ~.~.J _i_~J.J_L i. j TTFFTq..w-q CITY OF FRIDLEY !J.l.. ::;:::1, [.--'2:::-! ~!;Ti'T~, I . o z ~ r-E 0 Z PO 7 7 C TAYLDR ST, (31 7 U '" ~'~ m m m onestroo Rosene Anderlik & Associates Engineers & Architects Bonestroo, Rosene, Anderh7¢ and ,Associates, Inc, is an Affirmative Action/Equal Opportunity Employer Principals; Otto G. Bonestroo, RE. - Joseph C, Anderlil~, RE. · Marvin L. Sorvala, RE.. Richard E, Turner, RE, · Glenn R. Cook, RE. · Robert G. Schunicht, RE. · Jerry A. Bourdon, P,E. · Robert ~/. Rosene, RE. and Susan M. Eberlin, CRA., Senior Consultants Associate Princ,__:!s: Howard A. Sanford, RE. · l{eit~h Richard ~(/, Foster, P.E. · David O. Loskota, RE. · Robert C. Russek, A.I.A. · Mark A. Hanson, RE. · Michael T, Rautmann, RE. · Ted /(.Field, RE. · Kenneth R Anderson, RE. - Mark R. Rolls, RE, - Sidney R ~,~/illiamson, RE, ES. · Robert E Kotsmith". Agnes M. Ring · Michael R Rau, RE. Allan Rick Schmidt, RE, Offices: St. Paul, Rochester, ~.~/Jllmar ~nd St. Cloud. MN · MiJwaukee, ~'ebsite: www. bonestroo.com DRAFT FEASIBILITY STUDY FOR STORMWATER IMPROVEMENTS JACKSON POND SYSTEM COLUMBIA HEIGHTS, MINNESOTA BRAA FILE NO. 33207 This report presents the results of our stormwater improvements feasibility study for the Jackson Pond system. As detailed in our scoping study report dated 11/25/97 the Jackson Pond system included five specific flood prone areas. These areas are as follows (see Figure 1): 1. Jackson Pond 2. 4500 block of Washington Street NE 3. 4300 block of Washington Street NE 4. 1307 42nd Avenue NE 5. Tyler Place NE and 44th Avenue NE in the scoping study we also had included the alley between 5th and 6th Streets NE. As noted in that report, we did not feel that this isolated sanitary backflow warranted analysis separate from a general study of the City's infiltration and inflow (I/I) problems. Since the City is not proceeding with an I/I study at this time, this area will not be covered in this feasibility report. We have separated this report into five sections based on the five areas listed above. Each section begins with an introduction to the problem area followed in sequence by the following sections: Analysis and Results, Alternatives, Cost Estimates, and Recommended Alternative. At the end of this report are a location map and report figures. Please note that elevations are in the City of Minneapolis datum, followed in paranthesis by the USGS datum. The USGS datum is obtained from the Minneapolis datum by adding 710.3 feet. 2335 West Highway 36 · St. Paul. MN 5~i~ , 612-636-460O- Fax: 612-636-1311 Jackson Pond 1.1. Introduction This area includes Jackson Pond itself and its immediate vicinity. More Specifically, this section concerns itself with the flooding that occurred at 43rd Avenue NE and Jackson Street NE, the operation of the Jackson Pond outlet, the potential for stormwater backup into the sanitary sewer system, and the operation of the 60-inch trunk line under 44th Avenue NE. As noted in resident survey responses, flooding regularly occurs at the intersection of Jackson Street NE and 43rd Avenue NE. During the storms of July 1, 11, and 13, 1997, this was also the case. The larger of the storms, that of July 1, caused flooding that reached the garage at 4256 Jackson Street NE. Our field survey information puts this garage at an approximate elevation of 183.3' (893.6'). AcroSs the street from 4256 Jackson Street NE lies a concrete spillway constructed to convey storm water from the intersection into Jackson Pond. The spillway invert elevation is approximately 182.0' (892.3'). Jackson Pond's primary outlet consists of a 48-inch CMP connected to the 60-inch trunk at a manhole on 43rd Avenue NE. An aluminum flap gate at the manhole prevents backflow into the pond from the trunk line. To this pipe's east lies a 42-inch inlet from the same trunk that conveys flow from the trunk to the pond or from the pond to the trunk, depending upon the head difference between the two. Jackson Pond can overflow into the sanitary sewer system via a release pipe at its south end. Pond water can back into a manhole connected to this pipe and then enter the sanitary sewer system. The reverse can also occur. Two flap gates can prevent this connection, but during the storms of July 1997 these gates were open., As mentioned above, Jackson Pond discharges into the 60-inch trunk under 44th Avenue NE. This trunk conveys stormwater to the west and meets a 36-inch trunk line at University Avenue. From University Avenue, the storm sewer runs west then north where it meets a 76-inch pipe that carries water to the Mississippi River. 1.2.Analysis and Results Using the XP-SWMM32 computer software, we analyzed the Jackson Pond system from Labelle Pond to well past the trunk connection at University Avenue. In order to simplify our modeling, we analyzed the system's performance for the storm of July 1, 1997 and not for the subsequent July 11 and July 13 storms. The tipping bucket rain gauge at the public works facility indicated that the July 1 storm was the most intense of the July storms-; with over 3.64 inches of rain in 3.5 hours and 2.9 inches in the first hour. Our model suggests that flow over the spillway should have been sufficient to prevent the flooding near the garage at 4256 Jackson Street NE. Anecdotal evidence from residents suggests and our model verifies that ponding does occur at this intersection and that the ponding persists long after large storms have blown over. Our field survey information confirms that water will rise 0.5 ft in the intersection before overflowing down the spillway, but this should in no way flood any adjacent structures. Again, anecdotal evidence from City staff suggests that the spillway became clogged with debris and that this held water back to the level seen on July 1. Our results give a July 1 high water level (HWL) for Jackson Pond of 178.7' (889.0'), so the pond did not overtop its banks and cause flooding - a conclusion which is supported by resident testimony. The aluminum flap gate delays the Jackson Pond discharge until surcharge subsides in the 60-inch trunk. Our model suggests that this outlet works well and allows the full utilization of Jackson Pond's storage without flooding adjacent property. ~ Our results indicate that Jackson Pond discharged a 2-cfs peak flow into the sanitary sewer system. Once the City controls its i/I problem in this area, this connection should be eliminated. 1.3. Recommended Alternative We recommend that the City reconstruct the spillway at Jackson and 43rd. The existing spillway invert elevation of 182.0' (892.3') would suffice. The spillway design should consist of a 16' wide trapezoidal cross-section to a typical catch- basin/manhole. After the manhole the spillway should flare so that excess flow enters Jackson Pond over a wide area. Figure 2 provides some details of this construction. 1.4. Cost Estimate As detailed in Table 1, the estimated cost for this improvement is $11,775. Table 1 Estimated Cost: Jackson Pond Spillway Item Unit Quantity Unit Cost Price Concrete, 6-inch cast in place Common borrow Reconstruct CB-MH Sod SF 1,800 $3.50 TN 350 5.00 LS 1 500 SY 1 O0 3.50 $6,300 1,750 500 350 Estimated Construction Cost 5% Contingencies $8,900 445 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $9,345 1,869 $11,214 561 $11,775 4500 Block of Washington Street NE 2.1. Introduction The storm sewer that conveys flows from this area does not connect to the Jackson Pond system. We attached it to the Jackson Pond Feasibility Study because it was included with the Jackson Pond system in the scoping study. The Iow point of the 4500 block flooded during all three of the July storms. The residents here have witnessed similar flooding in other years for storms of varying intensities. At this Iow point, the grate elevations of the two catch basins are 187.5' (897.8') and 187.7' (898.0'). The lowest house elevation is 188.4' (898.7') and occurs at 4542 Washington Street NE. In an effort to reduce flooding at this .. location, City staff recently installed an additional catch basin. 2.2. Analysis and Results With existing pipe sizes, the XP-SWMM32 model developed for this area predicts flooding for storms as small as the 1-year storm event (2.3 inches of rainfall over 24 hours). For the event of July 1, 1997, the model calculates a HWL of 190.3' (900.6'). Due to the lack of pipe capacity in this area, flood levels persist well beyond the tapering of rainfall intensity. Table 2 summarizes the results of several storms with the existing pipe network. Conflicting anecdotal evidence made it difficult to calibrate the model for this area. For instance, the resident at 4540 Washington Street NE reported water up to but not flooding her home. Field surveys have established 190.6' (900.9') as the Iow elevation of this house. On the other hand 4559 Washington Street NE, which is higher, reported water entering through Iow house openings. 2.3. Recommended Alternative Berm construction may protect these homes from smaller events but would raise the flood stage for larger events. Our modeling suggests that a 25% reduction in the area below 190.3' (which would likely occur in berming around these houses) raises the July 1 HWL to 190.6' (900.9'). if berming reduced the area below 190.3' (900.6') by 50%, then the HWL for the July storm would rise to 190.8' (901.1'). Most likely, there is not enough area '~round these houses to berm to 190.8'. Since berming cannot solve the area's flooding problem, we looked at new trunk storm sewer under Washington Street NE and ponding in McKenna Park as the only. feasible alternative (see Figure 3). We evaluated improvements that could lower the 100-year HWL below the house at 4542 Washington Street NE. Accomplishing this requires larger storm sewer under Washington Street NE to McKenna Park. Because it is not economically feasible to replace any of the trunk storm sewer under 48th Avenue NE, the recommended improvements cannot increase peak flows downstream of the park. This requires a pond in McKenna Park. The pond will need 1.6 acres of land at pond HWL and 2.9 ac-ft of flood storage. We recommend a dry pond 5 feet in depth. Construction of this pond will require the removal of much of the 8-inch and 10-inch storm sewer within the park. Table 2 Storm Summary: 4500 Block of Washington Street NE Rainfall HWL Low House Freeboard Storm (in) (City Datum) (City Datum) (ft) 1 -year 2.3 189.4 -1.0 Before 5-year 3.1 189.7 -1.3 Improve 50-year 5.3 190.4 -2.0 ments 100-year 6.0 190.5 188.4 -2.1 .' July 1 3.64 190.3 -1.8 After 100-year 6.0 187.1 1.3 Improve ments July 1 3.64 187.9 0.5 1) Beyond the modeling period of 3.5 hours. Please note that the calculated 100-year flood level is higher than that for the July 1 storm under the existing system but lower under the proposed system. The proposed system substitutes conveyance (larger storm sewer) for storage (flooding around homes). Since the 100-year storm has lower rainfall intensifies and higher rainfall volume than the July storm, it is not surprising that the 100-year HWL reacts differently to the proposed improvements. 2.4. Cost Estimate The estimated cost for stormwater improvements on Washington Street NE (from the 4500 block to 47th Street NE) and in McKenna Park is approximately $283,500. A detailed cost estimate follows is presented in Table 3. Item Table 3 Estimated Cost: 4500 Washington Street NE Unit Quantity Unit Price Cost 15-inch 21 -inch 27-inch 33-inch 36-inch 12-inch 36-inch Rip rap Mobilization Remove concrete curb and gutter B618 curb and gutter Full depth pavement reclamation Common Excavation, street, off-site disposal Subgrade preparation Select granular borrow Aggregate base, class V, in place Bituminous base type 31B 'Bituminous wear type 41B 12-inch RCP RCP RCP '. RCP RCP RCP FES FES Remove existing storm sewer 6' manhole 4' Diameter CB/MH Excavation, pond, off-site disposal Traffic control LS 1 $15,000 LF 1,800 1.00 LF 1,800 6.00 SY 3,400 0.75 CY 2,670 7.00 SY 4,000 0.65 TN 2,640 5.00 TN 1,770 6.50 TN 280 30 TN 280 32 LF '100 22 LF 20 25 LF 82 35 LF 107 50 LF 594 65 LF 475 70 EA 1 600 LF 1 1,700 CY 40 40 LF 1,000 5.00 EA 4 2,000 EA 2 1,500 CY 2,300 7.00: LS 1 2,000 $15,000 1,800 10,800 2,550 18,690 2,600 13,200 11,505 8,400 8,960 2,200 500 2,870 : 5,350 38,610 33,250 600 1,700 1,600 5,000 8,000 3,000 16,100 2,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $214,285 10,714 $224,999 45,000 $269,999 13,500 $283,499 3. 4300 Block of Washington Street NE 3.1. Introduction Similar to the 4500 block, flooding regularly occurs at the Iow point of the 4300 block of Washington Street NE. During all three storms of July 1997, floodwater inundated the basement at 4330 Washington Street NE, ponded against the foundation of 4332, and flooded the garage at 4332. Our field survey confirms that the house at 4330 Washington Street NE lies below the lowest catch basin by approximately 0.3' and that Iow areas below street elevation surround 4332. A private alley slopes toward 4330 Washington Street NE from the south, delivering its runoff to this lot. 3.2. Analysis and Results With existing pipe sizes, the XP-SWMM32 model developed for this area predicts a HWL for the July 1, 1997 storm of 188.3' (898.6'). The homes at 4330 and 4332 Washington Street NE have Iow elevations of 186.6' (896.9') and 187.5' (897.8') respectively. Based on anecdotal evidence, the calculated HWL matches.well to that observed on July 1. The stormwater ponded at this site comes primarily from the intersection of 43rd Avenue NE and Washington Street NE. Though several catch basins serve this intersection, the 12-inch pipe to which they drain is undersized. This results in runoff bypassing these catch basins and collecting at the iow point one-half block north. The bypass manhole at the low point allows flow to travel either north to the 60-inch trunk or east to Jackson Pond. Computer results suggest that surcharge on the pipe to the east and Iow capacity on the pipe to the north combine to produce the flooding in this area. : 3.3. Alternatives 3.3.1. Alternative 1 This alternative consists of the purchase and demolition of the home at 4330 Washington Street NE and berming around 4332 (see figure 4). The abandoned lot would remain a city-owned outlot for temporary stormwater storage and would be excavated for grading around the house at 4332 Washington Street NE. The berm around 4332 Washington Street NE would rise to an elevation of 188.5' (898.8'). Sump pumps would discharge the runoff collected within the area surrounded by the berm to the adjacent catch basins. We recommend that the. abandoned lot be excavated beyond the volume required to construct the berm' so that there is a net increase in storage at this site. The outlot would lie below curb elevation but could drain to the existing storm sewer through a 12-inch plastic pipe and ditch type catch basin. Our field survey information indicates that, in order to match the berm into existing ground, grading would extend at least one lot to the north of 4332 Washington Street NE. Any lot isolated within the berm will require sump pumps. 3.3.2. Alternative 2 This alternative involves the reconstruction of Washington Street NE to 43rd Avenue NE and the replacement of the existing 310' of 15-inch RCP pipe with the same length of 36c-inch RCP (see Figure 4). Since the existing manhole has insufficient diameter to accept this pipe, this would also be replaced. Table 4 shows the effect this project would have on the HWL for this site. Table 4 Storm Summary: Alternative 2 Improvements HWL 4330 4332 Storm elevation elevation (City datum) (City datum) (City datum) Before Improvements July 1 188.3 After July 1 186.7 186.6 187.5 Improvements 100- 186.4 year Please note that this alternative provides protection for the home at 4330 -_ Washington Street NEfor the 100-year storm but not for the July 1, 1997 storm. The level of protection (0.1 feet of freeboard) is less than that typically provided by new construction (1 to 2 feet of freeboard). 3.4. Cost Estimates We have provided cost estimates for both alternatives. Table 5 presents our Alternative 1 estimate while Table 6 presents the Alternative 2 estimate. Table 5 Estimated Cost: Alternative 1, 4300 Block of Washington St NE item Unit Quantity Unit Price Cost Purchase and demolition 4330 Washington LS Excavation and embankment CY Sod SY 2' x 3' catch-basin EA Sump pumps EA 12-inch PE pipe LF 6-inch PE pipe, from sump pumps LF 1 $75,000 $75,000 150 10 1,500 210 5.00 1,050 1 1,000 1,000 2 500 1,000 40 20 800 160 10 1,600 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $81,950 4,098 $86,O48 17,210 $103,257 5,163 $108,420 Item Table 6 Estimated Cost: Alternative 2, 4300 Block Washington St NE Unit Quantity Unit Price Cost Mobilization Remove concrete curb and gutter B618 curb and gutter Full depth pavement reclamation Common excavation, off-site disposal Subgrade preparation .Select granular borrow Aggregate base, class V, in place Bituminous base type 31B Bituminous wear type 41 B 36-inch RCP Remove 15-inch RCP Replace diversion manhole Aluminum flap gate Traffic control Cut into existing manholes LS I $4,000 LF 620 1.00 LF 620 6.00 SY 1,360 0.75 CY 1,070 7.00 SY 1,600 0.65 TN 1,060 5.00 TN .900 6.50 TN 110 30 TN 110 32 LF 310 70 LF 310 5.00 EA 1 4,000 EA 1 2,000 LS 1 2,000 EA 1 750 $4,000 62O 3,720 1,020 7,490 1,040 5,300 5,850 3,300 3,520 21,700 '~1,550 4,000 2,000 2,000 750 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $67,860 3,393 $71,253 14,251 $85,504 4,275 $89,779 3.5. Recommended Alternative (For discussion with City Staff) '!307 42nd Avenue NE 4.1. Introduction Several problems surface at this site, some of which appear on a yearly basis. This home sits at the bottom of a steep hill. Storm sewer conveys runoff from this site to the west, where it connects with the outlet from LaBelle Pond. Since there are no intermediate catch basins along the hill to the east, large volumes of runoff at high velocity regularly jump th~ curb in front of 1307 42nd Avenue NE and enter the back and side yards, from where the water cannot drain. The catch basin in front of the house is not located at the Iow point, which is in front of the home's driveway. The house is not much higher than the curb, while the driveway slopes downward to the garage and the backyard. The resident claims the water jumps the curb and flows down the driveway several times a year. 4.2.Analysis and Results Street and driveway reconstruction to contain stormwater in the gutter would protect this home from small storms with return periods of 5 years and less. For the storms of July 1997, water ponded in this area, which indicates that simply improving gutter flow would not suffice for larger storms. For this Iow area at 1307 42nd Avenue NE, our XP-SWMM32 model calculated a July I HWL of 217.1' (927.4'). The model calculated the same HWL for the 100-year storm. Field surveying conducted by City staff gives 216.9' (927.2') as the lowest house elevation. Anecdotal evidence suggests that the HWL for the July I storm was higher than our model indicates. We feel this is due to gutter flow entering the property from the driveway. Once within the property this water cannot drain except through infiltration and ,evaporation. The elevation of the catch basin grate in front o'f this house is approximately 216.3', or 0.6' lower than the house. For large events, system capacity is not sufficient to adequately drain this area. Since there is no overflow from this Iow point, water ponds until drained by the storm. sewer. Our modeling shows that the reduction in pipe size from a 42-inch to a 36- inch at 43rd Avenue NE and Pierce Street NE causes a backwater effect upstream to Labelle Pond and 42"d Avenue NE. During the early stages of the July 1 storm, water flowed against pipe grade. Not until the peak flows had passed from the Storm sewer at 43rd Avenue NE and Pierce Street NE did significant discharge occur from Labelle Pond and 42nd Avenue. 4.3.Alternatives 4.3.1. Alternative 1 The first alternative involves installation of an additional 18-inch pipe under 42nd Avenue NE. From an existing catch basin, this pipe would run approximately 220 feet west. It then would turn 90 degrees south and run approximately 160 feet to Labelle Pond through City owned property. The new pipe would cross above the existing 15-inch pipe with approximately 1.0' of clearance. This pipe installation would involve reconstruction of up to 300 feet of 42nd Avenue NE. Our model predicts a 0.5' reduction in the July 1 HWL from this installation (see Table 7). It bears repetition that.gutter flow into the property should be eliminated as part of any alternative. Additionally, for both alternatives, we recommend a sump pump 10 connected to the storm sewer system capable of draining the low areas around the house. Table 7 summarizes the effects of alternative 1. Table 7 Storm Summary: Alternative 1, 1307 42nd Avenue NE HWL Low House Freeboard Storm (City datum) (City datum) (ft) Before Improvements July 1 217.1 -0.2 After Improvements July 1 216.6 216.9 0.3 100-year 216.5 0.4 item 4.3.2. Alternative 2 Alternative 2 involves berming around the front 0f the home at 1307 42"d Avenue NE. The berm would tie into existing ground one lot to the east and west. Our - XP-SWMM32 model indicates that berming to 218.0' (928.3') across the front of the property would no'[ raise the HWL for either the July 1, 1997 or the 100-year storm above 217.1, provided that sufficient sump pump capacity is present to drain the area within the berm. 4.4. Cost Estimates We have provided cost estimates for both alternatives. Table 8 applies to alternative 1, installation of an 18-inch RCP; while Table 9 applies to alternative 2, berming around 1307 42nd Avenue NE. Table 8 Estimated Cost: Alternative 1, 1307 42nd Avenue NE Unit Quantity Unit Price Cost Mobilization Remove concrete curb and gutter B618 curb and gutter Full depth pavement reclamation Subgrade preparation Common excavation Select granular borrow Aggregate base, class V, in place Bituminous base type 31B Bituminous wear type 41B 18-inch RCP Cut into existing manhole Sump pumps LS 1 $2,500 LF 600 1.00 LF 600 6.00 SY 870 0.75 SY 1040 0.65 CY 700 7.00 TN 690 4.84 TN 460 5.59 TN 75 30 TN 75 32 LF 380 30 EA 1 750 EA 2 500 $2,500 6OO 3,600 653 676 4,900 3,340 2,571 2,250 2,400 11,400 750 1,000 6-inch PE pipe, for sump pumps 4' standard manhole Traffic control LF 140 10 1,400 EA 1 1,500 1,500 LS 1 2,000 2,000 item Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST Table 9 Estimated Cost: Alternative 2, 1307 44TM Avenue NE Unit Quantity Unit Price $41,540 2,077 $43,616 8,723 $52,340 2,617 $54,957 Cost Mobilization Remove concrete curb and gutter B618 curb and gutter Excavation and embankment Sod Reconstruct driveway apron Sump pumps 6-inch PE pipe, for sump pumps Traffic control LS I $400 LF 30 3.00 LF 30 17 CY 75 10 SY 75 5.00 LS 1 1,000 EA 2 500 LF 140 10 LS 1 250 $400 9O 510 750 375 1,000 1,000 1,400 25O = Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $5,775 289 $6,064 1,213 $7,277 364 $7,640 4.5. Recommended Alternative (Discuss with City Staff) Tyler Place NE and 44th Avenue NE 5.1. Introduction A 48-inch CMP carries the LaBelle Pond outflow as well as local runoff through this site. These flows pass with some surcharge through this pipe, a surcharge that releases from a beehive catch basin in back of 1016 44 Avenue NE. During the July storms this backflow.flooded an adjacent garage, one nearby apartment building, and entered the sunken patio of 1016 44th Avenue NE (but did little damage to the house itself). The pipe here is shallow; in fact, pinholes in the CMP spout water through the ground to the surface, causing bubbling of water out of the ground. 5.2. Analysis and Results The XP,SWMM32 model developed for the Jackson Pond System calculated a July 1, 1997 HWL of 206.0' (916.3') for this area. The Iow building elevation is 205.1' (915.4') and is found at the apartment building to the west of 1016 44th Avenue NE. The ground elevation at the lip of the drop to the patio at 1016 44th Avenue NE is approximately 205.3' (915.6'). Anecdotal evidence suggest that the July 1 HWL in this area was 2'-3' above the rim of the backyard CB. Field survey data collected by the City gives this rim elevation as 203.7' (914.0'), which would put the July 1 HWL somewhere between 205.7' (916.0') and 206.7' (917.0'). Watermarks on a nearby garage would suggest a HWL closer to 205.7'. Our computer-generated HWL of 206.0' (916.3') matches reasonably well with anecdotal data. Our modeling suggests that for a wide variety of st°rms ponding will occur in this" area. The 48-inch CMP was not designed to carry flows from larger storms without the buildup of head on the system. That built-up head becomes evident around this backyard catch basin when water surges out from the pipe into the surrounding yard and parking lot. This, coupled with a sizable direct drainage area from the backyards that cannot enter the already full pipe, causes the chronic flooding in this area. 5.3. Recommended Alternative The recommended alternative for this area is to berm around all low structures to an elevation of 206.3' (916.6'). Replacing the leaky 48-inch CMP with an equivalent size RCP would reduce the 100-year and July 1 HWLs (both 206.0") by 0.2'. This alone would not solve the flooding problems in this area. Replacement of the 48-inch CMP will likely be needed in the near future, since evidence suggests the pipe is falling apart. It is recommended to be included in the City's CiP. To avoid exacerbating flooding in this area and new flooding in others, the replacement of this pipe should generally proceed from downstream to upstream. Our cost estimates include 227' of this installation. We do not recommend anything larger than 48-inch diameter pipe since no excess capacity exists in the system downstream. 5.4. Cost Estimate Table 10 presents the estimated cost for this improvement. Item Table 10 Estimated Cost: Tyler Place NE and 40th Avenue NE Unit Quantity. Unit Price Cost Mobilization Grading and embankment 48-inch RCP Remove 48-inch CMP Restoration, sod Sump pumps 6-inch plastic pipe, sumps to manhole Restoration: pavement, fences, etc. 8' diameter manholes LS 1 $3,000 $3,000 CY 200 10 2,000 LF 227 80 18,160 LF 227 10 2,270 S¥ 250 5.00 1,250 EA 3 5O0 1,5O0 LF 180 10 1,800 LS 1 5,000 5,000 EA 2 4,000 8,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $42,980 2,149 $45,129 9,026 $54,155 2,708 $56,863 14 / c_ C) ~ om© Z Frl Frl CITY OF FRIDLEY Z m c) C) 0 Z 0 Z C ~0 Z ~ i QUINCY AVE. Zoo ~0 Z I 0 Z j c.._ 0 ..k,, 0 0 .-t 0 Z i-rI z Fr..i 24." < 14.' 25' 51 ' rtl 12' STORMWATER DETENTION POND HCKENNA PARK 29, ~ 23' 181' 281' 48TH 47TH AVE. 1/2 AVE. 47TH AVE. 46TH /2 AVF. f c_ 0 -ID o 0~ 0 Frl Frl c~ I Frl o Z R U') T F'q I Z ~ --- ' © --~ 0 0 z 7 U') rd') I ~ ~ X )>. Fq · U-D I (.JO ~ 313' 29' ~,~ 0 0 I I O~ Fq Z Fq Z -O ~0 0 -O 0 o ~ 42" ZZ gA ~ O~ Bonestroo Rosene nderlik & Associates Engineers & Architects Bonestroo, Rosene, Anderfik and Associates, Inc. is an Affirmative Action/Equal Opportunity Employer Principals: Otto G. Bonestroo, RE. · Joseph C. Anderlik, RE. · Marvin L. Sorvala, RE. · Richard E. Turner, RE. · Glenn R. Cook, P.E. · Robert G. Schunicht, P.E. Robert ~ Rosene, RE. and Susan M. Eberlin, C.RA., Senior Consultants Associate Principals: Howard A. Sanford, RE. - Keith Richard ~(/. Foster, RE. · David O. Loskota, RE. · Robert C. Russek, AJ.A. Michael T. Rautmann, P£. · Ted K.Pield, RE, · Kenneth R Anderson, Sidney R '¢/illiarnson, RE., L,S. - Robert R Kotsmith Offices: St. Paul, Rochester, ~/illmar and St. Cloud, MN FEASIBILITY STUDY' FOR STORMWATER IMPROVEMENTS MCKINLEY STREET NE AND 40TM AVENUE NE COLUMBIA HEIGHTS, MINNESOTA BRAA FILE NO. 33208 This report presents the results of our stormwater improvements feasibility study for the McKinley Street NE and 40th Avenue NE area. Damaging floods occurred here on July 1, 11, and 13 of 1997, though resident surveys indicate that intersection flooding is a regular occurrence. We have completed our analysis of this area according to the plan detailed in our scoping study of 11/25/97. This report begins with an introduction to the problem area, followed in sequence by the following sections: Analysis and Results, Alternatives, Cost Estimates, and the Recommended Alternative. A location-map and report figures are at the end of the report. Please note that elevations are in the city of Minneapolis datum, followed in parenthesis by the USGS datum. The USGS datum is obtained from the Minneapolis datum by adding 710.3 feet. 1. INTRODUCTION As stated above, flooding occurred here for ali three of the large July 1997 storms. Several homes on 40th Avenue NE, north of the intersection with McKinley Street NE, were flooded by stormwater that rose up to 2.5 feet above the street catch basins (see Figure 1). Our discussions with residents and City staff indicate that flooding is a chronic problem here, even for events smaller than those encountered in July of 1997. 2. ANALYSIS AND RESULTS We analyzed the pipe network upstream and downstream of the flood prone area (see Figure 2). Runoff from a large area, including Hart Lake and portions of Minneapolis and St. Anthony, converges at this intersection via the storm sewer network. We 2335 West Highway 36 · St. Paul. IVIN 55113 - 612-636-4600 · Fax: 612-636-1311 delineated these inputs and entered them into our computer model. Additionally, we located and characterized sources of overland flow such as overflow from catch basins on McKinley, Cleveland, and 39thl/2. The tipping bucket rain gauge at the public works facility indicated that the July 1 storm was the most intense of the three July storms, with over 3.64 inches of rain in 3.5 hours and 2.9 inches in the first hour. Our model, developed with the XP-SWMM32 software, simulated the July I storm and supports the anecdotal evidence obtained from several residents living adjacent to this intersection. The topographic survey of this area conducted by City staff, when compared to this anecdotal evidence, indicates that the high water level (HWL) for July 1 was approximately 237.7' (948.0)'. Our model calculates a July 1 HWL of 237.6' (947.9') and thus shows reasonable calibration to the actual storm event. Our model indicates that pipe surcharge (the buildup of stormwater in the pipe network .such that additional stormwater is held back) cannot by itself account for the water levels seen at this intersection, and that local overland flow produces the bulk of the flooding. This overland flow travels down both 39thl/2 and McKinley to the intersection of 40th and McKinley, where it ponds until the already full pipe network can accommodate it. ,. 3. ALTERNATIVES Various alternatives to address the flooding problem were considered. Our analYsis" showed that storm sewer construction to reroute Minneapolis and St. Anthony flow down Stinson Boulevard to Silver Lake does not significantly lower the HWL at McKinley and 40th. We did find that a trunk size pipe from McKinley and 40th to Silver Lake would be effective. This line could run from the intersection due north through backyards or, alternately, could run east to Stinson Boulevard from where it would travel north to Silver Lake. In either case Minneapolis's and the bulk of St. Anthony's stormwater would continue along their present route. .. Our model indicates that stormwater ponding would be an equally effective alternative. Specifically, ponding in Prestemon Park could store excess overland flow, slowly discharging this water over the course of several hours. This type of solution does not require a trunk size storm sewer. These two alternatives are addressed 'in more detail below. 3.1.Alternative 1: Ponding in Prestemon Park This alternative (see Figure 2) involves excavation and embankment to form two detention basins within Prestemon Park. These basins would detain flow from Cleveland, 39th1/2, and McKinley. This alternative requires reconstruction of street grades at the intersections of Cleveland and 40th and Cleveland and 39th1/2, and along McKinley near the 15ark entrance. This reconstruction involves additional catch basins and pipe to convey flow into the detention basins. We propose intersection reconstruction at Cleveland and 40th so that overland flow from the north and west flows down Cleveland from 40t~ to 39thl/2 and into proposed detention basin A. Likewise, reconstruction of McKinley routes flow from McKinley to proposed detention basin B. Excavation within the park for detention basin A necessitateS removing some relatively large trees. Both detention basins would be dry between storms, and would discharge to the existing storm sewer under the park. · Table 1 summarizes the flood benefits of this alternative. Table t Storm Summary: Alternative l, Ponding in Prestemon Park HWL - 40~ Low Free- HWL - HWL - Rainfall & McKinley House board Basin A Basin Storm B .' (in) (City (City (ft) (City (City datum) datum) datum) datum) Before Improvements July 1 3.64 237.6' 0.1 NA NA July 1 3.64 236.0' 1.7 237.8' 238.3 After 100-year 6.0 236.02' 237.7' 1.7 238.2 238.3 Improvements 50-year 5.3 236.0' 1.7 238.0 238.2 10-year 4.1 235.96' 1.7 237.7 238.2 5-year 3.5 235.93' 1.7 237.3 237.8 3.2.Alternative 2: Trunk Storm Sewer This alternative involves installing a trunk storm sewer from the intersection of McKinley and 40th north to Silver Lake. Figure 2 shows a potential alignment for installation through backyards, as well as an alignment along 40~h Avenue'NEand Stinson Boulevard. The backyard alternative includes an estimated 750 feet of 42- inch reinforced concrete pipe (RCP), several manholes, easement acquisition, some street reconstruction, and significant restoration. Additionally, there are substantial logistical problems in cutting along lot lines directly north to Silver Lake. Routing east to Stinson Boulevard and then down Stinson to Silver Lake involves more street reconstruction but less restoration and less easement acquisition. Table 2 summarizes the benefits of this alternative (applicable to both alignments) in relation to the 100-year, 2,,4 hour, and July 1, 1997 storms. Table 2 Storm Summary: Alternative 2, Trunk Storm Sewer Storm HWL Low House Freeboard (City datum) (City datum) (ft) Before Improvements July 1 237.6' ,0.1 237.7' After July 1 236.1' 1.6 Improvements 100-yea r 236.0' 1.7 4. COST ESTIMATES Table 3 presents the cost estimate for Alternative 1 as described above and shown on Figure 2. Table 3 Estimated Cost: Alternative 1, Ponding in Prestemon Park : Item Unit Quantity Unit Cost Price Mobilization LS Excavation and embankment, off-site disposal CY 12-inch RCP LF 15-inch RCP LF 18-inch RCP LF 12-inch FES EA 18-inch FES EA 2' x 3' catch basin EA Rip rap CY Clearing and grubbing LS Seeding and mulching, pond areas AC Trees EA Remove and replace concrete curb and gutter LF Full depth pavement reclamation SY Subgrade preparation SY Common excavation CY Select granular borrow TN Aggregate base, class V, in place.. TN Bituminous base type 31B TN Bituminous wear type 41B TN 1 $5,oo0 1,200 7.00 210 22 60 25 170 30 1 600 2 800 8 1,000 30 40 I 1,000 I 4,000 15 200 900 7 1,900 O.75 1,900 0.65 1,200 7 1,450 5 970 6.5 157 30 157 32 $5,000 8,400 4,620 1,500 5,100 6OO 1 600 8 000 1 200 1 000 4 000 3 000 6 300 1 425 1 235 8 540 7 250 6 305 4710 5 024 Traffic control LS 1 5,000 5,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. "5~o"Capitalized Interest' TOTAL ESTIMATED COST $89,809 4,490 $94,299 .18,860 $113,159 5,658 $118,817 Tables 4 and 5 present cost estimates for Alternative 2 (for both the backyard alignment and the 40th and Stinson alignment, respectively) as described above and shown on Figure 2. Table 4 Estimated Cost: Alternative 2, Trunk Storm SeWer- Backyard Alignment item ' Unit Quantity Unit Price Cost Mobilization LS 1 $10,000 42-inch RCP LF 750 75 8' diameter manholes EA 4 4,000 42-inch FES EA 1 2,000 Rip rap CY 30 40 Clearing and grubbing LS 1 5,000 Sod SY 4,000 3.00 Trees EA 15 200 Restoration LS 1 20,000 Easement acquisition, permanent AC 0.30 130,000 Easement acquisition, temporary AC 0.75 20,000 Remove & replace concrete curb & gutter LF 450 7.00 Full depth pavement reclamation SY 720 0.75 Subgrade preparation SY 720 0.65 Select granular borrow TN 495 5.00 Aggregate base, class V, in place TN 330 6.50 Bituminous base type 31B TN 60 30 Bituminous wear type 41B TN 60 32 Traffic control LS 1 5,000 $10 56 16 2 000 250 000 000 1 200 5 000 12 000 3 000 20.000 39.000 15.000 3 150 540 468 2,475 2 145 1 800 1 920 5 000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $196 948 9 847 $206 795 41,359 $248,154 12,408 $26O,562 Table 5 Estimated Cost: Alternative 2, Trunk Storm Sewer- 40th and Stinson Alignment Item Unit Quantity Unit Price Cost Mobilization LS 42-inch RCP LF 8-ft diameter manholes EA CB-MH 2' x 3' EA 42-inch FES EA Rip rap CY Sod SY Easement acquisition, permanent AC _~asement acquisition, temporary AC Remove and replace concrete curb and gutter LF Full depth pavement reclamation SY Subgrade preparation SY Select granular borrow TN Aggregate base, class V, in place TN Bituminous base type 31B TN Bituminous wear type 41B TN Traffic control LS 1 $10,000 $10,000 1,453 75 108,975 5 4,000 20,000 1 1,000 1,000 1 2,000 2,000 30 40 1,200 2,000 3 6,000 0.2 130,000 26,000 0.45 20,000 9,000 2,I00 7 14,700 4,000 0.75 3,000.. 4,000 0.65 2,600 3,100 5 15,500 2,100 6.5 13,650 330 30 9,900 330 32 10,560 1 5,000 5,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $259,085 12,954 $272,039 54,408 $326,447 16,322 $342,769' 5. RECOMMENDED ALTERNATIVE Based on cOst and logistics, we recommend Alternative 1. Both the disruption to local residents and the Cost are greater under Alternative 2, while the benefit is the same as that provided by Alternative 1. The recommended alternative does not address problems of high ground water experienced in this area. The area around the intersection of McKinley and 40th had historically been a pond. This pond was filled upon development of the area, but ground water levels persist. In order to address groundwater seepage into basements, a drain tile system for this ar..ea might be required. Such a tile system would likely need to be drained to Silver Lake. o Z Fq T m I I Oo D'I m ~,, :...,: u i ..._~--x/~ ...... . , , ~'~ '"~' ~';~~ ....... ~1-~¢-~-, .: '-:'--:: ~. ......... ... ,- --'~ CITY OF FRIDLEY ~ ~ ~ ~ 147 ' _~ ---- · · ~...-% ~. , ~ ....... . ~.~ ~_~ -~- ~ Ii~~i ~~r~=-~ .... r . , .~F%~-~¢ ' ,~lJI I ' ~lb-~ It i-' -'" I--~ .............. 1~ ,~ .... ~ b'-~J ! ~', :; i'-, _J i i: : i i .......... , ........ ,.,. ,,, :,, .............. ,~ ........... ~,, ....... ~! ~ ...........~ [ - :~__ .... ~ .l~. '~, ' .... '~.':~:::ljk t..q: ..... , -- ,. , i [' :'i : ; !~:.li;']]~ I i' ' i: l!~a, I ~ --~ '~ :~ r-~' ~--l'~ '1~'~ : '!~--~' i, : : ~ ¢ ...... ~ ~ .... ~-~ ".'' k~, . ~ ........ ~ ........... ~ . , , ,~ , ..... 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' I .. . - ~ ~ ~l -,.;~, , , ,,,:~ ....... .~ .......... .., .. i : /IIk- i .t~ ~ ............... .'t~~ 1.,.2_..I [j_~jZ',,,/~ ;'~,~~~/'" ~~-}:~/~~, ~ :: ,.'. ~ I k._,.:.,...¢:~L. :. =- ~:,.-~~5:J~~.~-~:~ ......... 109' L_ 4-OTH AVE. ~,~' 175' Z W" O_ 12' zz 42' ~ ,.313' W W Z W Bonestroo Rosene Anderlik & Associates Engineers & Architects Bonestroo, Rosene, Anderlik and Associates, Inc, is an Affirmative Action/Equal Opportun/ty Employer Principals: Otto G, f3onestroo, P.E. · Joseph C. Anderlik, RE. - Marvin L. Sprvala, P.E. · Richard E. Turner, RE. · Glenn R. Codk, P.E. · Robert G. Schunicht,, RE. · Jerry A, Bourdon, RE. - Robert ~K/. Rosene, P.E. and Susan M. Eberlin, CRA., Senior Consultants Associate Principals: Howard A. Sanford, RE. · Keith A, Gordon, RE. · Robert R. Pfefferle, RE. · Richard ~(/. Foster, RE. · David O. Loskota, RE, · Robert C. Russek, A.I.A. · Mark Michael T. Rautmann, RE. - Ted K.F/eld, RE. - Kenneth R Anderson, RE. · Mark R. Rolls, RE, · Sidney R ~(/illiamson, RE., L.S, · Robert F, Kotsmith · Agnes M. Ring · Michael R Rau, RE. Allan Rick Schmidt, RE. ' Offices: St. Paul, Rochester, ~(/i~lrnar and St. Cloud, MN · Milwaukee, g~ebsite; www. bonestroo.com DRAFT FEASIBILITY STUDY FOR STORMWATER IMPROVEMENTS MONROE STREET NE AND 49TM t/2 AVENUE NE COLUMBIA HEIGHTS, MINNESOTA BRA FILE No. 33209 This report presents the results of our stormwater improvements feasibility study for the intersection of Monroe Street NE and 49th ¼ Avenue NE. As detailed in our scoping study report dated 11/25/97, the intersection has been prone to flooding during large rainfall events. Please note that elevations referenced in this report are in the city of Minneapolis datum, followed in parenthesis by the USGS datum. The USGS datum is obtained from the Minneapolis datum by adding 710.3 feet. 1. INTRODUCTION The intersection of Monroe Street NE and 49th ½ Avenue NE flooded during all three of the July 1997 storms (see Figure 1). The water rose to at least three feet above the catch basins. During the July 1 storm, the runoff overflowed to the west, toppling retaining walls on its way to the alley behind Monroe Street NE. The inlet grate elevations at this intersection are at 184.31' (894.61'), 184.35' (894.65'), and 184.08' (894.38') (see Figure 2). The high water level (HWL) for the July 1 storm was estimated at 186.84' (897.14'). The lowest house elevation at this intersection is 186.60' (896.9') and occurs at 4935 Monroe Street NE. Residents have indicated that flooding also occurs at this intersection during smaller storms throughout the summer. The area that drains to this intersection includes the Central Avenue business district that contains large amounts of impervious surfaces. The runoff from this area is conveyed down 50th Avenue NE. Although the storm sewer network is laid out to convey this flow north to Sullivan Lake, most of the runoff bypasses the catch basins at Monroe Street NE and 50th Avenue NE, and overflows south to the intersection of Monroe Street NE and 49th ~ Avenue NE. 2335 West Highway 36 · St. Paul. MN 55113 · 612-636-4600 · Fax: 612-636-1311 2. ANALYSIS AND RESULTS We modeled the stormwater system using XP-SWMM32 computer software. For existing conditions, the model predicts yard flooding around the intersection of Monroe Street NE and 49th ~ Avenue NE for storms as small as a 1-year storm event (2.3 inches of rainfall over 24 hours). For the event on July 1, 1997, the model calculates a high-water level (HWL) of 186.3' (896.6'), slightly lower than the observed HWL of 186.84' (897.14'). This computed HWL was determined with the assumption that all the catch basins were free of clogging from leaves and debris. Homeowners explained that these drains were partially plugged during the July storms, thus causing the HWL to exceed the predicted level. Table I summarizes the modeling results of several storms with the existing pipe network. Table 1 Storm Summary :~:;~,.:, Return a'nfall !. ,HWL ','"%: ~ Low:HoUse'; :Freeboard :.~ _ . :, ~¥:~:,:~.:.:~':¢:.~ i .. :,: (in) '. (Ci~DatUrn); (City Datum) i. (fi)., (hr) 1-year 2.3 185.1' 186.6' 1.5 2.5 5-year 3.1 185.2' 186.6' 1.4 4.0 50-yea r 5.3 186.1' 186.6' 0.5 7.0 100-year 6.0 186.3' 186.6' 0.3 8.5 July 1, 1997 3.64 186.3' 186.6' 0.3 (3.5+) 1) Beyond the modeling period of 3.5 hours. 3. ALTERNATIVES A number of alternatives to capture and divert runoff from the Central Avenue business district were considered. These included combinations of new storm sewer and street regrading. It was found that these alternatives were very expensive and did little to reduce HWLs at the intersection of Monroe Street NE and 49TM ~ Avenue NE. The local drainage area to this intersection is large enough such that unacceptable HWLs would still occur; diverting the Central Avenue area tended only to reduce the duration of the flooding. For this reason, the two alternatives presented below focus not on diverting runoff away from the affected intersection, but rather on conveying flows out of the intersection. 3,1 Alternative 1: Improve Catch Basins This alternative includes the replacement or rehabilitation of the existing catch basin structures at the intersection of Monroe Street NE and 49th Avenue NE (see Figure 2). Our field survey results and residents comments indicate that the existing catch basins become plugged with debris on a regular basis. The structures would be replaced with catch basin inlets that have larger curb inlets and vane grates which minimize clogging. As part of this work, localized curb raising behind the catch basins will be required. This alternative also includes the installation of a speed bump or minor road raise on 50th Avenue NE immediately east of the intersection with Monroe Street NE. This will create minor ponding at the catch basins on 50th Avenue NE, increasing the capacity of the catch basins. The catch basins will thus capture more of the runoff from the Central Avenue business district, conveying it north to Sullivan Lake. This alternative results in a HWL of 186.3' (896.6') at the intersection of Monroe Street NE and 49th ~ Avenue NE. This will provide a freeboard of 0.3 feet to the lowest home at this intersection (4935 Monroe Street NE), at an elevation of 186.6' (896.9). We recommend that the catch basins at this intersection be inspected and cleaned on a regular basis, particularly in the spring and fall. In addition, the streets draining to the intersection should be placed on a priority street sweeping schedule. 3.2 Alternative 2: Trunk Storm Sewer This alternative involves the installation of a storm sewer system from the intersection of Monroe Street NE and 49th % Avenue NE, north to Sullivan Lake. New catch basins will be installed at the intersections of Monroe Street NE and 49th ~ Avenue NE and 50th Avenue NE that will attach to the new system. Figure 2 presents the proposed layout of the system. Due to the topography of the area, the storm sewer will become fairly deep in some sections. Table 2 shows the effect this project would have on the HWL at the intersection of Monroe Street NE and 49th % Avenue NE. Table 2 Alternative 2 Improvements ~;;.Datum); Datum) , :~ (fi):.=;!!:-~'!': ¥:;~: (hr) Before improvements July 1 186.8 186.6 -0.2 .... After July 1 ' 185.6 186.6 1.0 2.0 Improvements 100 year 185.6 186.6 1.0 2.0 4. COST ESTIMATES Cost estimates are provided for both alternatives. 4.1 Alternative I Cost Estimate Table 3 presents the cost estimate for Alternative 1, Improve Catch Basins. Table 3 Estimated Cost: Alternative Item Mobilization Remove concrete curb and gutter B618 curb and gutter Bituminous type 31B Bituminous type 41B R~3250-1 Catch Basin Traffic Control Unit Quantity Unit Price LS 1 $1000 LF 400 1.00 LF 400 6.00 TN 115 30 TN 115 32 EA 6 350 LS 1 500 Estimated Construction Cost 5% contingencies 20% Design, Inspection, Admin 5% Capitalized Interest TOTAL ESTIMATED COST Cost $i000 400.00 2,400 3,450 3,680 2,100 500 $13,530 677 $14,207 2,841 $17,048 852 $17,900 4.2 Alternative 2 Cost Estimate Table 4 presents the cost estimate for Alternative 2, Trunk Storm Sewer. Table 4 Estimated Cost: Alternative 2 Item Mobilization Remove concrete curb and gutter B618 curb and gutter Full depth pavement Reclamation Common Excavation, street, off- site disposal Subgrade preparation Select granular borrow. Aggregate base, class 5, in place Bituminous type 31B Bituminous type 41B 15-inch RCP 18-inch RCP 27-inch RCP, some over depth 30-inch RCP, some over depth 42-inch RCP Rip Rap 6' manhole, some over depth 2' x 3' Catch Basin R-3250-1 Catch Basin Traffic Control Unit Quantity Unit Price LS 1 $10,000 LF 2400 1.00 LF 24O0 6.00 SY 4540 0.75 CY 3560 7.00 SY 5340 0.65 TN 3520 5.00 TN 2350 6.50 TN 375 30 TN 375 32 LF 50 25 LF 50 30 LF 600 50 LF 350 55 LF 350 75' CY 30 40 EA 5 2,000 EA 5 1,000 EA 6 350 LS 1 2,000 Estimated Construction Cost 5% contingencies 20% Design, Inspection, Admin 5% Capitalized Interest TOTAL ESTIMATED COST Cost $1o,ooo 2,400 14,400 3,405 24,920 3,471 '17,600 15 275 11 250 12000 I 250 I 500 30 000 19,250 26,250 1,200 o,ooo 5,000 2,100 2,000 $213,271 10,664 $223,935 44,787 $268,722 13,436 $282,158 5. RECOMMENDED ALTERNATIVE We recommend proceeding with Alternative 1 on an interim basis,' and closely monitoring flood levels in the future. In addition, the catch basins should be regularly inspected and maintained, and the streets on the vicinity placed on a priority street sweeping schedule. In the future, particularly when Monroe Street NE is scheduled for reconstruction, we recommend looking in greater detail at the alternative of constructing a new storm sewer to Sullivan Lake. Alternative 1 provides minor improvement to the drainage system and provides a freeboard of 0.3 feet to the lowest home in the area under the 100-year design storm. This level of protection is less than the desired freeboard of 1 to 2 feet. Alternative 2 provides 1 foot of freeboard but entailsa considerable investment in storm sewer improvements, potentially approaching the value of the affected homes. O Z Z I-q Z Frl C) ~ ........ ~, ~ ~ ,, .... ~: ~,~ ' r-'--, .... ,'~J ~,'-~.,.' ~.~.~ ..~ l :~ ......... ~ ..... J ....... i , ~ ,~.~=.~-~ .... , , ,,,..,~~ CITY OF FRIDLEY ~ A~ ~ ~T~ ~ 47 ~, : ...~,~-,.,~ ~,~, .~r~t~l~l~. -rm:']~. 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O Z ~o~° SULLIVAN LAKE / ~]-° z z z 0 ' ' PARK ~" ~'I '~ 21." / ' ~Jt 50TH 1/2 AVE. 10" ~ o ~ m 50TH AVE. 4~35 24"~ ~ ~" ' ~8" ~2' ,~ · 28' ez.,, ~ ~ 255' ~ ~'~ 269'o~ / (l~ 49TH 1_2 AVE. 30' 23' City of Columbia Heights Public Works Department Work Session Discussion Item Work session date: May 6, 1998 i x~-.x Prepared by: Kevin Hansen, Public Works Director/City Eng Item: Bonestroo Report - Presentation of Storm Water Feasibility Reports Background: As a result of surface water runoff from a series of storms during July 1997, several areas throughout the City of Columbia Heights experienced short term flooding. To analyze the problem area and prepare engineering reports describing solutions and cost analyses, the City Council authorized entering into a contract with the consulting engineering firm of Bonestroo, Rosene and Anderlik (BRA) at their October 13, 1997 meeting. Discussion: BRA's tasks include data collection, data analysis/additional data gathering, hydrologic modeling, develop recommended improvements and prepare and present final engineering report. Representatives from BRA will present engineering reports for the following areas: Corporate Limit area Jackson Pond System (and area) 40t~ Avenue and McKinley Street Monroe Street NE and 49 ½ Avenue NE A copy of each report is attached. Other areas identified in the scoping study were deemed to be more local in nature and may be addressed directly in the design phase. After discussion and input from City Council, final feasibility reports will be submitted for approval. The next course of action will be project selection, design and construction implementation phase, and developing a financing plan. Requested Action: Discussion and input for engineering reports. by the Council at a regular meeting. Revised reports should then be formally accepted Attachment: BRA Engineering Reports F:\wp51 \worksess\brassfr Bonestroo Rosene Anderlik & Associates Engineers & Architects Bonestroo, Rosene, Anderlik and Associates, Inc. is an Affirmative Action/Equal Opportunity Employer Principals: Otto G. Bonestroo, P_E~ - JOseph C. ,~,nderlik, RE, - Marvin L. Sorvala, RE. - Richard E. Turner, RE. · Glenn R. Coo~, RE. · Robert G. Schunicht, RE. · Jerry A, Bourdon, P.E. · Robert W. Rosene, RE. and Susan M. E'berlin, CRA., Senior Consultants Associate Principals: Howard A. Sanford, RE. - Keitb A. Gordon, RE. - Robert R. Pfefferle, RE. · Richard ~X,'. Foster, RE.. David O. Loskota, RE. - Robert C. Russek, A.LA. · Mark A. Hanson, RE. - Michael T, Rautmann, RE. · Ted K.FJeld, RE. - Kenneth R Anderson, RE. - Mark R. Rolls, RE. - Sidney R ~(/illiamson, RE., LS. · Robert F. Kotsmith - Agnes M. Ring · Michael R Rau, RE. · Allan Rick Schmidt, RE. Offices: St. Paul, Rochester, ~(/illmar and St. Cloud, MN ·Miiwaukee, WI t)~/ebsite: www. bonestroo.com DRAFT FEASIBILITY STUDY FOR STORMWATER IMPROVEMENTS CORPORATE LIMIT AREA COLUMBIA HEIGHTS, MINNESOTA BRAA FILE NO. 33210 This report presents the results of our stormwater improvements feasibility study for the Corporate Limit area. The Corporate Limit flooding occurred in July of 1997 along the Fridley/Columbia Heights border south of 52nd Avenue. We have completed our analysis of this area according to the plan detailed in our scoping study addendum of This report begins with an introduction to the problem area followed in sequence by the following sections: Analysis and Results, Alternatives, Cost Estimates, and the Recommended Alternative. A location map and report figure are at the end of this report. Please note that elevations are in the city of Minneapolis datum followed in parenthesis by the USGS datum. The USGS datum is obtained from the Minneapolis datum by adding 710.3 feet. 1. INTRODUCTION A chronic backyard flooding problem has existed at 1280 and 1298 52nd Avenue in the City of Fridley- along Fridley's border with Columbia Heights (see figure 1). These homes suffered flooding as a result of the July 1, 1997 storm. The home at 1280 52nd Avenue aisc had flooding during the July 11 storm. Recently, the two cities cooperatively placed an additional 36-inch pipe above the existing 36-inch storm sewer in this area. At its upstream end, this newer pipe connects to a 100-foot section of 36-inch corrugated steel slotted drainpipe. The two 36-inch pipes discharge to a single 24-inch pipe (see Figure 2). 2335 West Highway 36 · St. Paul. MN 55113 · 612-636-4600 · Fax: 612-636-1311 During the July storms, residents witnessed stormwater discharging at high pressure from the backyard catch basins. This discharge, combined with overflow from two catch basins on Polk Place, caused flooding in these backyards. 2. ANALYSIS AND RESULTS We analyzed the pipe network upstream and downstream of the flood prone area. Additionally, we located and characterized sources of overland flow such as the overflow from the catch basins at the intersection of Polk Place and Pierce Terrace. Anecdotal evidence obtained from resident interviews and water staining on the two homes suggest a July 1 high water level (HWL) of 234.1' (944.4'). The tipping bucket rain gauge at the public works facility indicated that the July 1 storm was the most intense of the three July storms, with over 3.64 inches of rain in 3.5 hours and 2.9 inches in the first hour. Our model, developed with the XP-SWMM32 software, simulated the July 1 storm and supports the anecdotal evidence obtained from residents nd at 1280 and 1298 52 Avenue. As mentioned above, water staining suggests a HWL of approximately 234.1' (944.4') for the July 1 storm. The two homes are both walkouts. The Iow openings for 1280 and 1298 52nd Avenue are 233.4' (943.7') and 233.9' (944.2'), respectively. Our model calculated a July 1 HWL of 233.9 (944.2'), which calibrates well with the observed HWL. 3. ALTERNATIVES Various alternatives were considered to address the flooding problem. Of these, four were studied in detail and are presented in this report. 3.1 Alternative 1: Berming in the Vicinity of 1280' and 1298 52nd Avenue NE. Alternative 1 involves constructing a berm to protect the homes at 1280 and 1298 52nd Avenue NE (see Figure 2). For this alternative, excavation and embankment should balance. If berm construction results in a net loss of storage, then the HWL for a given storm will rise. The berm top should rise to 234.9' (945.2'), which is approximately I foot above the calculated 100-year, 24-hour storm and July 1 HWLs. Since storage below 233.9' (944.2') must remain the same, some excavation will occur across the corporate boundary into Columbia Heights where several trees from 8 to 24 inches in diameter now grow. These would likely have to be removed. Additionally, the berm will tie in nd to high ground one lot to the east and west of 1280 'and 1298 52 Avenue NE, necessitating disturbance of property that has not experienced flooding. Drainage of areas isolated behind the berms would require sump pumps. 3.2 Alternative 2: Emergency overflow grading This alternative consists of grading an emergency overflow (EOF) below the current overflow elevation of 234.7' (945.0') so that 100-year protection is afforded the homes at 1280 and 1298 52nd Avenue NE. Overflow would flow down the current drainage easement to the Iow area off Polk Circle. From this Iow area, the flow enters the 36-inch trunk via two ditch type catch basins. This alternative includes clearing and grubbing within the existing city drainage easement so that disruptions to this flow are minimized. In addition to clearing and grubbing, landscape features, sheds, and woodpiles would also require removal. We recommend an EOF elevation of 232.4' (942.7'). Table I summarizes the effect this grading will have on the area around 1280 and 1298 52nd Avenue and as well as the Iow area off Polk Circle. There are several potentially adverse impacts to this alternative. There will be no defined flow path, so runoff may flow through or pond in backyards. There is a significant potential for erosion. Runoff may begin to cut a ravine, which could continue to erode and grow over time. This would cause sediment build-up in the downstream Iow area and potential clogging of the catch basins there. Table 1 High Water Levels, Alternative 2 Polk Circle 1280 & 1298 52nd Low HWL Freeboard Low HWL Freeboard Storm house House (city (city (city (city datum) datum) (ft) datum) datum) (ft) Before EOF July 1 207.3 1.4 233.9 -0.5 grading 208.7 233.4 After July 1 207.7 1.0 233.3 0.1 EOF grading 100-year 206.6 2.1 233.2 0.2 For the 100-year event, we calculate a peak flow of 27 cfs over the EOF and mean channel velocity of 6 feet per second (fps) to the downstream ponding area off Polk Circle. 3.3 Alternative 3: Overflow with standard pipe installation This alternative consists of approximately 600 feet of 18-inch reinforced concrete pipe (RCP), installed by open cut trenching to the p°nding area east of Polk Circle (see Figure 2). This pipe would be laid adjacent to the existing pipe and would discharge directly to the ponding area. This ponded stormwater would enter the trunk system through the beehive catch basins located at this Iow point. The existing overflow elevation would be lowered from 234.7' (945.0') to 232.4' (942.7'). This overflow would operate for storms in excess of the 10-year, 24~hour event. Grading would occur in the existing drainageway in conjunction with the pipe installation so that a clearly defined overflow route is created. Numerous trees, fences, sheds, and landscaping make this a politically sensitive alternative and create a large restoration cost. 3.4 Alternative 4: Overflow with directional bore pipe installation This alternative involves directional boring of a 20-inch (outside diameter) high density polyethylene pipe and is considered if resident resistance precludes open trench installation. As with alternative 3, this construction involves grading of an emergency overflow (EOF) at 232.4' (942.7'). Stormwater would overflow for storms greater than the 10- year event. Unlike alternative 3, no improvement of the drainage path beyond the limits of the EOF grading is proposed, so as to minimize disturbance of the area. This may result in maintenance problems in years when the EOF is topped (see discussion under Alternative 2). These long-term costs were not considered in the cost estimate for this alternative. Alternatives 3 and 4 are identical from a hydraulic perspective. Both require sufficient catch basin capacity near 1280 and 1298 52nd Avenue NE so that 20 cfs passes into the pipe under approximately 1.2 feet of head. We propose 2 catch basins with rim elevations of 942.0'. These should be covered by stool type ditch grates similar to Neenah R-4342. These have a relatively Iow profile, which would be more appropriate for installation in private backyards. Each grate should pass approximately 9 cfs under 1.2 feet of head. In considering alternatives 2, 3 and 4, it should be understood that passing water more quickly out of this area has the potential to flood the downstream ponding area if the catch basins there become clogged with debris. It has been indicated that water came within 5 feet (horizontally) of a home off Polk Circle. The corners of this home lie at approximately 208.7' (919.0') and 5 feet from this would suggest a July 1 HWL of 208.2 (918.5'). Our model predicts a July 1 HWL of 207.1' (917.4)' for this area and, after alternatives 3 and 4 described above, a July 1 HWL of 207.5 (917.8'). This discrepancy suggests that the catch basins did not drain the ponding area to their full capacity and that they might have been clogged. Table 2 summarizes the effects of the improvements proposed under Alternatives 3 and 4. Table 3 shows the effect these have on the downstream ponding area. The results are derived from the XP-SWMM32 model of the area. Table 2 Flows and High Water Levels, Alternatives 3 and 4 Freeboard Flow in Overflow HWL Storm proposed pipe Overflow Elevation (city datum) (ft) (cfs) (cfs) (city datum) Before Improvements July 1 233.9 -0.5 NA NA 234.7 July 1 232.9 0.5 22 21 100-yr 232.9 0.6 20 18 (6.0") After 50-yr 232.7 0.7 18 9 Improvements (5.3") 232.4 25-yr 232.6 0.8 15 3.5 (4.7") lO-yr 232.4 1.0 10 0 (4.1") Table 3 High Water Levels in Downstream Ponding Area Alternatives 3 and 4 HWL Low House Freeboard Storm (city datum) (city datum) (ft) Before Improvements July 1 207.3 1.4 After 208.7 Improvements July 1 207.5 1.2 4. COST ESTIMATES · Cost estimates are provided for all three alternatives. 4.1 Alternative 1 Cost Estimate Table 4 presents the cost estimate for Alternative 1, berming in the vicinity of 1280 and 1298 52nd Avenue NE. Table 4 Estimated Cost: Alternative Item Unit Quantity Unit Price Cost Mobilization Clearing and grubbing Excavation and embankment Sod Trees Sump pumps, PVC piping LS I $600 $600 LS 1 2,000 2,000 CY 150 10.00 1,500 SY 650 5.00 3,250 EA 15 200 3,000 EA 2 500 1,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $11,350 567 $11,917 2,383 $14,300 715 $15,015 4.2 Alternative 2 Cost Estimate Table 5 presents the cost estimate for alternative 2, emergency overflow grading. Table 5 Estimated Cost: Alternative 2 Item Unit Quantity Unit Cost Price Mobilization LS 1 $600 $600 Clearing and grubbing LS I 4,000 4,000 Excavation and embankment CY 270 10.00 2,700 Sod SY 800 5.00 4,000 Trees EA 6 200 1,200 Estimated Construction Cost 5% Contingencies $12,500 625 $13,125 20% Design, Inspection, Admin. 5% CapitaliZed Interest TOTAL ESTIMATED COST 2,625 $15,750 787 $16,537 4.3 Alternative 3 Cost Estimate Table 6 presents the cost estimate for Alternative 3, overflow with standard pipe installation. Easement acquisition costs are approximate. Table 6 Estimated Cost: Alternative 3 Item Unit Quantity Unit Price Cost Mobilization 18~inch RCP, some overdepth 18-inch FES Clearing and grubbing Common excavation, channel shaping Sod Trees CB-MH 2'x3' 4' Diameter MH Easement acquisition, temporary LS I $5,000 $5,000 LF 660 30.00 t9,800 EA 1 1,000 1,000 LS 1 5,000 5,000 CY 520 7.00 3,640 SY 4200 3.00 12,600 EA 45 200 9,000 EA 2 1,000 2,000 EA 1 1250 1,250 AC 0.5 20,000 10,000 Estimated Construction Cost 5% Contingenci'es 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $69 290 3 465 $72 755 14 551 $87 306 4 365 $91 671 Item 4.4 Alternative 4 Cost Estimate Table 7 presents the cost estimate for alternative 4, overflow with directional bore pipe installation. Easement acquisition costs are approximate. Table 7 Estimated Cost: Alternative 4 Unit Quantity LS 1 LF 630 Mobilization 20~inch OD HDPE, some overdepth Unit Price Cost $6,000 140 $6,000 88,200 18-inch RCP Clearing and grubbing Common excavation, EOF shaping Sod Trees CB-MH 2'x3' Easement acquisition, temporary LF 30 30 LS I 2,500 CY 140 7.00 SY 1400 3.00 EA 15 200 EA 3 1,000 AC 0.5 20,000 9OO 2,5O0 98O 4,200 3,000 3,000 10,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $118,780 5,939 $124,719 24,944 $149,663 7,483 $157,146 5. RECOMMENDED ALTERNATIVE We recommend alternative 1. This approach provides 1 foot of freeboard and costs significantly less than the alternatives 3 and 4. In addition, it has the advantage of not passing additional flow to the downstream ponding area. These additional flows combined with the potential for channel erosion argue against alternative 2. Although the model shows adequate freeboard for the home adjacent to the .downstream ponding area (even after alternative 2, 3 and 4 improvements), and shows a delayed peak from the overflow down to this area, anecdotal evidence suggests that water levels were higher than those calculated by the model. This may be due to catch basin clogging, but is of enough concern to warrant caution. Although alternative 2 has a relatively Iow cost, we do not recommend it due to the potential for significant erosion. Further study of the flow path downstream of the emergency overflow is required, and a swale or channel design likely would be warranted. This drainage work would add to the cost and disruption associated with this alternative. 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Robert V(/, Rosene, RE. and Susan M. Eberlin, C.RA., Senior Consultants Associate Principals: Howard A. Sanfbrd, RE. · Keith A. Gordon, RE. · Robert R. Pfefferle, RE.. Richard ~(/. Foster, RE. · David O. Loskota, RE. · Robert C. Russek, A,I.A. · Mark A. Hanson, RE. - Michael T. Rautmann, RE. Sidney R V(/illiarnson, Allan Rick Schmidt~ Offices: St, Paul, Rochester, v(/illrnar and St. Cloud, MN · Milwaukee, ~/I gYeb$ite; www.bonestroo.com DRAFT FEASIBILITY STUDY FOR STORMWATER IMPROVEMENTS JACKSON POND SYSTEM COLUMBIA HEIGHTS, MINNESOTA BRAA FILE NO. 33207 This report presents the results of our stormwater improvements feasibility study for the Jackson Pond system. As detailed in our scoping studY report dated 11/25/97 the Jackson Pond system included five specific flood prone areas. These areas are as follows (see Figure 1): 1. Jackson Pond 2. 4500 block of Washington Street NE 3. 4300 block of Washington Street NE 4. 1307 42nd Avenue NE 5. Tyler Place NE and 44th Avenue NE In the scoping study we also had included the alley between 5th and 6th Streets NE. As noted in that report, we did not feel that this isolated sanitary backfiow warranted analysis separate from a general study of the City's infiltration and inflow (I/I) problems. Since the City is not proceeding with an I/I study at this time, this area will not be covered in this feasibility report. We have separated this report into five sections based On the five areas listed above. Each section begins with an introduction to the problem area followed in sequence by the following sections: Analysis and Results, Alternatives, Cost Estimates, and Recommended Alternative. At the end of this report are a location map and report figures. Please note that elevations are in the City of Minneapolis datum, followed in paranthesis by the USGS datum. The USGS datum is obtained from the Minneapolis datum by adding 710.3 feet. 2335 West Highway 36 - St. Paul. MN 55113 - 612-636-4600'- Fax: 612-636-1311 1. Jackson Pond 1.1. Introduction This area includes Jackson Pond itself and its immediate vicinity. More Specifically, this section concerns itself with the flooding that occurred at 43rd Avenue NE and Jackson Street NE, the operation of the Jackson Pond outlet, the potential for stormwater backup into the sanitary sewer system, and the operation of the 60-inch trunk line under 44th Avenue NE. As noted in resident survey responses, flooding regularly occurs at the intersection of Jackson Street NE and 43rd Avenue NE. During the storms of July 1, 11, and 13, 1997, this was also the case. The larger of the storms, that of July 1, caused flooding that reached the garage at 4256 Jackson Street NE. Our field survey information puts this garage at an approximate elevation of 183.3' (893.6'). AcroSs the street from 4256 Jackson Street NE lies a concrete spillway constructed to = convey storm water from '[he intersection into Jackson Pond. The spillway invert elevation is approximately 182.0' (892.3'). : Jackson Pond's primary outlet consists of a 48-inch CMP connected to the 60-inch trunk at a manhole on 43rd Avenue NE. An aluminum flap gate at the manhole prevents backflow into the pond from the trunk line. To this pipe's east lies a 42-inch inlet from the same trunk that conveys flow from the trunk to the pond or from the pond to the trunk, depending upon the head difference between the two. Jackson Pond can overflow into the sanitary sewer system via a release pipe at its south end. Pond water can back into a manhole connected to this pipe and then enter the sanitary sewer system. The reverse can also occur. Two flap gates can prevent this connection, but during the storms of July 1997 these gates were open., As mentioned above, Jackson Pond discharges into the 60-inch trunk under 44th Avenue NE. This trunk conveys stormwater to the west and meets a 36-inch trunk line at University Avenue. From University Avenue, the storm sewer runs west then north where it meets a 76-inch pipe that carries water to the Mississippi River. 1.2.Analysis and Results Using the XP-SWMM32 computer software, we analyzed the Jackson Pond system from Labelle Pond to well past the trunk connection at University Avenue. In order to simplify our modeling, we analyzed the system's performance for the storm of July 1, 1997 and not for the subsequent July 11 and July 13 storms. The tipping bucket rain gauge at the public works facility indicated that the July 1 storm was the most intense of the July storms-; with over 3.64 inches of rain in 3.5 hours and 2.9 inches in the first hour. Our model suggests that flow over the spillway should have been sufficient to prevent the flooding near the garage at 4256 Jackson Street NE. Anecdotal evidence from residents suggests and our model verifies that ponding does occur at this intersection and that the ponding persists long after large storms have blown over. Our field survey information confirms that Water will rise 0.5 ft in the intersection before overflowing down the spillway, but this should in no way flood any adjacent structures. Again, anecdotal evidence from City staff suggests that the spillway became clogged with debris and that this held water back to the level seen on July 1. Our results give a July 1 high water level (HWL) for Jackson Pond of 178.7' (889.0'), so the pond did not overtop its banks and cause flooding - a conclusion which is supported by resident testimony. The aluminum flap gate delays the Jackson Pond discharge until surcharge subsides in the 60-inch trunk. Our model suggests that this outlet works well and allows the full utilization of Jackson Pond's storage without flooding adjacent property. : Our results indicate that Jackson Pond discharged a 2-cfs peak flow into the sanitary sewer system. Once the City controls its I/I problem in this area, this connection should be eliminated. .3. Recommended Alternative We recommend that the City reconstruct the spillway at Jackson and 43rd. The existing spillway invert elevation of 182.0' (892.3') would suffice. The spillway design should consist of a 16' wide trapezoidal cross-section to a typical catch- basin/manhole. After the manhole the spillway should flare so that excess flow enters Jackson Pond over a wide area. Figure 2 provides some details of this construction. 1.4. Cost Estimate As detailed in Table 1, the estimated cost for this improvement is $11,775. item Table 1 Estimated Cost: Jackson Pond SpillWay Unit 'Quantity Unit Cost Price Concrete, 6-inch cast in place Common borrow Reconstruct CB-MH Sod SF 1,800 $3.50 TN 350 5.00 LS 1 500 SY 100 3.50 $6,300 1,750 5OO 35O Estimated Construction Cost 5% Contingencies $8,900 445 3 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST 4500 Block of Washington Street NE 2.1. Introduction $9,345 1,869 $11,214 561 $11,775 The storm sewer that conveys flows from this area does not connect to the Jackson Pond system. We attached it to the Jackson Pond Feasibility Study because it was included with the Jackson Pond system in the scoping study. The Iow point of the 4500 block flooded during all three of the July storms. The residents here have witnessed similar flooding in other years for storms of varying intensities. At this Iow point, the grate elevations of the two catch basins are 187.5; (897.8') and 187.7' (898.0'). The lowest house elevation is 188.4' (898.7') and occurs at 4542 Washington Street NE. In an effort to reduce flooding at this : location, City staff recently installed an additional catch basin. 2.2. Analysis and Results With existing pipe sizes, the XP-SWMM32 model developed for this area predicts flooding for storms as small as the 1-year storm event (2.3 inches of rainfall over 24 hours). For the event of July 1, 1997, the model calculates a HWL of 190.3' (900.6'). Due to the lack of pipe capacity in this area, flood levels persist well beyond the tapering of rainfall intensity. Table 2 summarizes the results of several storms with the existing pipe network. Conflicting anecdotal evidence made it difficult to calibrate the model for this area. For instance, the resident at 4540 Washington Street NE reported water up to but not flooding her home. Field surveys have established 190.6' (900.9') as the Iow elevation of this house. On the other hand 4559 Washington Street NE, which is higher, reported water entering through Iow house openings. 2.3. Recommended Alternative Berm construction may protect these homes from smaller events but would raise the flood stage for larger events. Our modeling suggests that a 25% reduction in the area below 190.3' (which would likely occur in berming around these houses) raises the July 1 HWL to 190.6' (900.9'). If berming reduced the area below 190.3' (900.6') by 50%, then the HWL for the July storm would rise to 190.8' (901.1'). Most likely, there is not enough area ~round these houses to berm to 190.8'. Since berming cannot solve the area's flooding problem, we looked at new trunk storm sewer under Washington Street NE and ponding in McKenna Park as the only. feasible alternative (see Figure 3). We evaluated improvements that could lower the 100-year HWL below the house at 4542 Washington Street NE. Accomplishing this requires larger storm sewer under Washington Street NE to McKenna Park. Because it is not economically feasible to replace any of the trunk storm sewer under 48th Avenue NE, the recommended improvements cannot increase peak flows downstream of the park. This requires a pond in McKenna Park. The pond will need 1.6 acres of land at pond HWL and 2.9 ac-ft of flood storage. We recommend a dry pond 5 feet in depth. Construction of this pond will require the removal of much of the 8-inch and 10-inch storm sewer within the park. Table 2 Storm Summary: 4500 Block of WaShington Street NE Rainfall HWL Low House Freeboard Storm (in) (City Datum) (City Datum) (ft) 1-year 2.3 189.4 -1.0 Before 5-year 3.1 189.7 -1.3 Improve 50-year 5.3 190.4 -2.0 ments 100-year 6.0 190.5 188.4 -2.1.' July 1 3.64 190.3 -1.8 After 100-year 6.0 187.1 1.3 Improve July 1 3.64 187.9 0.5 ments 1) Beyond the modeling pedod of 3.5 hours. Please note that the calculated 100-year flood level is higher than that for the July 1 storm under the existing system but lower under the proposed system. The proposed system substitutes conveyance (larger storm sewer) for storage (flooding around homes). Since the 100-year storm has lower rainfall intensities and higher rainfall volume than the July storm, it is not surprising that the 100-year HWL reacts differently to the proposed improvements. 2.4. Cost Estimate The estimated cost for stormwater improvements on Washington Street NE (from the 4500 block to 47th Street NE) and in McKenna Park is approximately $283,500. A detailed cost estimate follows is presented in Table 3. Item Table 3 Estimated Cost: 4500 Washington Street NE Unit QUantity Unit Price' Cost 15-inch 21 -inch 27-inch 33-inch 36-inch 12-inch 36-inch Rip rap Mobilization Remove concrete curb and gutter B618 curb and gutter Full depth pavement reclamation Common Excavation, street, off-site disposal Subgrade preparation Select granular borrow Aggregate base, class V, in place Bituminous base type 31B 'Bituminous wear type 41B 12-inch RCP RCP RCP '. RCP RCP RCP FES FES Remove existing storm sewer 6' manhole 4' Diameter CB/MH Excavation, pond, off-site disposal Traffic control LS 1 $15,000 $15,000 LF 1,800 1.00 ..1,800 LF 1,800 6.00 10,800 SY 3,400 0.75 2,550 CY 2,670 7.00 18,690 SY 4,000 0.65 2,600 TN 2,640 5.00 13,200 TN 1,770 6.50 11,505 TN 280 30 8,400 TN .280 32 8,960 LF '100 22 2,200 LF 20 25 500 LF 82 35 2,870 LF 107 50 : 5,350 LF 594 65 38,610 LF 475 '70 33,250 EA 1 600 600 LF 1 1,700 1,700 CY 40 40 1,600 LF 1,000 5.00 5,000 EA 4 2,000 8,000 EA 2 1,500 3,000 CY 2,300 7.00: 16,100 LS 1 2,000 2,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized IntereSt TOTAL ESTIMATED COST $214,285 10,714 $224,999 45,000 $269,999 13,500 $283,499 3. 4300 Block of Washington Street NE 3.1. Introduction Similar to the 4500 block, flooding regularly occurs at the iow point of the 4300 block of Washington Street NE. During all three storms of July 1997, floodwater inundated the basement at 4330 Washington Street NE, ponded against the foundation of 4332, and flooded the garage at 4332. Our field survey confirms that the house at 4330 Washington Street NE lies below the lowest catch basin by approximately 0.3' and that Iow areas below street elevation surround 4332. A private alley slopes toward 4330 Washington Street NE from the south, delivering its runoff to this lot. 3.2. Analysis and Results With existing pipe sizes, the XP-SWMM32 model developed for this area predicts a HWL for the July 1, 1997 storm of 188.3' (898.6'). The homes at 4330 and 4332 Washington Street NE have Iow elevations of 186.6' (896.9') and 187.5' (897.8') respectively. Based on anecdotal evidence, the calculated HWL matches well to that observed on July 1. The stormwater ponded at this site comes primarily from the intersection of 43rd Avenue NE and Washington Street NE. Though several catch basins serve this intersection, the 12-inch pipe to which they drain is undersized. This results in runoff bypassing these catch basins and collecting at the Iow point one-half block north. The bypass manhole at the iow point allows flow to travel either north to the 60-inch trunk or east to Jackson Pond. Computer results suggest that surcharge on the pipe to the east and Iow capacity on the pipe to the north combine to produce the floodi.ng in this area. : 3.3. Alternatives 3.3.1. Alternative 1 This alternative consists of the purchase and demolition of the home at 4330 Washington Street NE and berming around 4332 (see figure 4). The abandoned lot would remain a city-owned outlot for temporary stormwater storage and would be excavated for grading around the house at 4332 Washington Street NE. The berm around 4332 Washington Street NE would rise to an elevation of 188.5' (898.8'). Sump pumps would discharge the runoff collected within the area surrounded by the berm to the adjacent catch basins. We recommend that the. abandoned lot be excavated beyond the volume required to construct the berm' so that there is a net increase in storage at this site. The outlot would lie below curb elevation but could drain to the existing storm sewer through a 12-inch plastic pipe and ditch type catch basin. Our field survey information indicates that, in order to match the berm into existing ground, grading would extend at least one lot to the north of 4332 Washington Street NE. Any lot isolated within the berm will require sump pumps. 3.3.2. Alternative 2 This alternative involves the reconstruction of Washington Street NE to 43rd Avenue NE and the replacement of the existing 310' of 15-inch RCP pipe with the same length of 36;-inch RCP (see Figure 4). Since the existing manhole has insufficient diameter to accept this pipe, this would also be replaced. Table 4 shows the effect this project would have on the HWL for this site. Table 4 Storm Summary: Alternative 2 Improvements HWL 4330 4332 Storm elevation elevation (City datum) (City datum) (City datum) Before Improvements July 1 188.3 After July 1 186.7 186.6 187.5 Improvements 100- 186.4 year Please note that this alternative provides protection for the home at 4330 -. Washington Street NEfor the 100-year storm but not for the July 1, 1997 storm. The level of protection (0.1 feet of freeboard) is less than that typically provided by new construction (1 to 2 feet of freeboard). 3.4. Cost Estimates We have provided cost estimates for both alternatives. Table 5 presents our Alternative 1 estimate while Table 6 presents the Alternative 2 estimate. Table 5 Estimated Cost: Alternative 1, 4300 Block of Washington St NE Item Unit Quantity Unit Price Cost Purchase and demolition 4330 Washington LS Excavation and embankment CY Sod SY 2' x 3' catch-basin EA Sump pumps EA 12-inch PE pipe LF 6-inch PE pipe, from sump pumps LF I $75,000 $75,000 150 10 1,500 210 5.00 1,050 1 1,000 1,000 2 500' 1,000 40 20 800 160 10 1,600 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $81,950 4,098 $86,048 17,210 $103,257 5,163 $108,420 Item Table 6 Estimated Cost: Alternative 2, 4300 Block Washington St NE Unit Quantity Unit Price Cost Mobilization Remove concrete curb and gutter B618 curb and gutter Full depth pavement reclamation Common excavation, off-site disposal Subgrade preparation .Select granular borrow Aggregate base, class V, in place Bituminous base type 31B Bituminous wear type 41B 36-inch RCP Remove 15-inch RCP Replace diversion manhole Aluminum flap gate Traffic control Cut into existing manholes LS I $4,000 $4,000 LF 620 1.00 620 LF 620 6.00 3,720 SY 1,360 0.75 1,020 CY 1,070 7.00 7,490 SY 1,600 0.65 1,040 TN 1,060 5.00 5,300 TN ..900 6.50 5,850 TN 110 30 3,300 TN 110 32 3,520 LF 310 70 21,700 LF 310 5.00 "1,550 EA 1 4,000 4,000 EA 1 2,000 2,000 LS 1 2,000 2,000 EA 1 750 750 = Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $67,860 3,393 $71,253 14,251 $85,504 4,275 $89,779 3.5. Recommended Alternative (For discussion with City Staff) 1307 42nd Avenue NE 4.1. Introduction Several problems surface at this site, some of which appear on a yearly basis. This home sits at the bottom of a steep hill. Storm sewer conveys runoff from this site to the west, where it connects with the outlet from LaBelle Pond. Since there are no intermediate catch basins along the hill to the east, large volumes of runoff at high velocity regularly jump th-~ curb in front of 1307 42nd Avenue NE and enter the back and side yards, from where the water cannot drain. The catch basin in front of the house is not located at the Iow point, which is in front of the home's driveway. The house is not much higher than the curb, while the driveway slopes downward to the garage and the backyard. The resident claims the water jumps the curb and flows down the driveway several times a year. 4.2. Analysis and Results Street and driveway reconstruction to contain stormwater in the gutter would protect this home from small storms with return periods of 5 years and less. For the storms of July 1997, water ponded in this area, which indicates that simply improving gutter flow would not suffice for larger storms. For this iow area at 1307 42nd Avenue NE, our XP-SWMM32 model calculated a July 1 HWL of 217.1' (927.4'). The model calculated the same HWL for the 100-year storm. Field surveying conducted by City staff gives 216.9' (927.2') as the lowest house elevation. Anecdotal evidence suggests that the HWL for the July 1 storm was higher than our model indicates. We feel this is due to gutter flow entering t~e property from the driveway. Once within the property this water cannot drain except through infiltration and .evaporation. The elevation of the catch basin grate in front of this house is approximately 216.3', or 0.6' lower than the house. For large events, system capacity is not sufficient to adequately drain this area. Since there is no overflow from this Iow point, water ponds until drained by the storm sewer. Our modeling shows that the reduction in pipe size from a 42-inch to a 36-' inch at 43rd Avenue NE and Pierce Street NE causes a backwater effect upstream to Labeile Pond and 42nd Avenue NE. During the early stages of the July 1 storm, water flowed against pipe grade. Not until the peak flows had passed from the storm sewer at 43rd Avenue NE and Pierce Street NE did significant discharge occur from Labelle Pond and 42nd Avenue. 4.3.Alternatives 4.3.1. Alternative 1 The first alternative involves installation of an additional 18-inch pipe under 42nd Avenue NE. From an existing catch basin, this pipe would run approximately 220 feet west. it then would turn 90 degrees south and run approximately 160 feet to Labelle Pond through City owned property. The new pipe would cross above the existing 15-inch pipe with approximately 1.0' of Clearance. This pipe installation would involve reconstruction of up to 300 feet of 42nd Avenue NE. Our model predicts a 0.5' reduction in the July 1 HWL from this installation (see Table 7). it bears repetition that.gutter flow into the property should be eliminated as part of any alternative. Additionally, for both alternatives, we recommend a sump pump l0 Item connected to the storm sewer system capable of draining the low areas around the house. Table 7 summarizes the effects of alternative 1. Table 7 Storm SUmmary.· Alternative 1, 1307 42nd Avenue NE HWL Low House Freeboard Storm (City datum) (City datum) (ft) Before Improvements July 1 217.1 -0.2 216.9 After Improvements July 1 216.6 0.3 100-year 216.5 0.4 4.3.2. Alternative 2 Alternative 2 involves berming around the front Of the home at 1307 42nd Avenue NE. The berm would tie into existing ground one lot to the east and west. Our: XP-SWMM32 model indicates that berming to 218.0' (928.3') across the front of the property would not raise the HWL for either the July 1, 1997 or the 100-year storm above 217.1, provided that sufficient sump pump capacity is present to drain the area within the berm. 4.4. Cost Estimates We have provided cost estimates for both alternatives. Table 8 applies to alternative 1, installation of an 18-inch RCP; while Table 9 applies to alternative 2, berming around 1307 42nd Avenue NE. . Table 8 Estimated Cost: Alternative 1, '1307 42nd Avenue NE Unit Quantity Unit Price Cost Mobilization Remove concrete curb and gutter B618 curb and gutter Full depth pavement reclamation Subgrade preparation Common excavation Select granular borrow Aggregate base, class V, in place Bituminous base type 31B Bituminous wear type 41B 18-inch RCP Cut into existing manhole Sump pumps LS 1. $2,500 LF 600 1.00 LF 600 6.00 SY 870 0.75 SY 1040 0.65 CY 700 7.00 TN 690 4.84 TN 460 5.59 TN 75 30 TN 75 32 LF 380 30 EA 1 750 EA 2 500 $2,500 6OO 3,600 653 676 4,900 3,340 2,571 2,250 2,400 11,400 750 1,000 1! 6-inch PE pipe, for sump pumps 4' standard manhole Traffic control LF 140 10 EA 1 1,500 LS 1 2,000 1,400 1,500 2,000 Item Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST Table 9 Estimated Cost: Alternative 2, 1307 44th Avenue NE Unit Quantity Unit Price Cost $41,540 2,077 $43,6!6 8,723 $52,340 2,617 $54,957 Mobilization Remove concrete curb and gutter B618 curb and gutter Excavation and embankment Sod Reconstruct driveway apron Sump pumps 6-inch PE pipe, for sump pumps Traffic control LS 1 $400 $400 LF 30 3.00 90 LF 30 17 510 CY 75 10 750 SY 75 5.00 375 LS 1 1,000 1,000 EA 2 500 1,000 LF 140 10 1,400 LS 1 250 250 Estimated Construction Cost $5,775 5% Contingencies 289 $6,064 20% Design, Inspection, Admin. 1,213 .$7,277 5% Capitalized Interest 364 TOTAL ESTIMATED COST $7,640 4.5. Recommended Alternative (Discuss with City Staff) Tyler Place NE and 44th Avenue NE 5.1. Introduction A 48-inch CMP carries the LaBelle Pond outflow as well as local runoff through this site. These flows pass with some surcharge through this pipe, a surcharge that releases from a beehive catch basin in back of 1016 44 Avenue NE. During the July storms this backflow.flooded an adjacent garage, one nearby apartment building, and entered the sunken th patio of 1016 44 Avenue NE (but did little damage to the house itself). The pipe here is shallow; in fact, pinholes in the CMP spout water through the ground to the surface, causing bubbling of water out of the ground. 5.2. Analysis and Results The XP-SWMM32 model developed for the Jackson Pond System calculated a July 1, 1997 HWL of 206.0' (916.3') for this area. The Iow building elevation is 205.1' (915.4') and is found at the apartment building to the west of 1016 44th Avenue NE. The ground elevation at the lip of the drop to the patio at 1016 44th Avenue NE is approximately 205.3' (915.6'). Anecdotal evidence suggest that the July 1 HWL in this area was 2'-3' above 'the rim of the backyard CB. Field survey data collected by the City gives this rim elevation as 203.7' (914.0'), which would put the July 1 HWL somewhere between 205.7' (916.0') and 206.7' (917.0'). Watermarks on a nearby garage would suggest a HWL closer to 205.7'. Our computer-generated HWL of 206.0' (916.3') matches reasonably well with anecdotal data. Our modeling suggests that for a wide variety of stOrms Ponding will occur in this area. The 48-inch CMP was not designed to carry flows from larger storms without the buildup of head on the system. That built-up head becomes evident around this backyard catch basin when water surges out from the pipe into the surrounding yard and parking lot. This, coupled with a sizable direct drainage area from the backyards that cannot enter the already full pipe, causes the chronic flooding in this area. 5.3. Recommended Alternative The recommended alternative for this area is to berm around ali Iow structures to an elevation of 206.3' (916.6'). Replacing the leaky 48-inch CMP with an equivalent size RCP would reduce the 100-year and July 1 HWLs (both 206.0') by 0.2'. This alone would not solve the flooding problems in this area. Replacement of the 48-inch CMP will likely be needed in the near future, since evidence suggests the pipe is falling apart. It is recommended to be included in the City's CIP. To avoid exacerbating flooding in this area and new flooding in others, the replacement of this pipe should generally proceed from downstream to upstream. Our cost estimates include 227' of this installation. We do not recommend anything larger than 48-inch diameter Pipe since no excess capacity exists in the system downstream. 5.4. Cost Estimate Table 10 presents the estimated cost for this improvement. Item Table 10 Estimated Cost: Tyler Place NE and 40th Avenue NE Unit Quantity. Unit Price' Cost Mobilization Grading and embankment 48-inch RCP Remove 48-inch CMP Restoration, sod Sump pumps 6-inch plastic pipe, sumps to manhole Restoration: pavement, fences, etc. 8' diameter manholes LS 1 $3,000 $3,000 CY 200 10 2,000 LF 227 80 18,160 LF 227 10 2,270 SY 250 5.00 1,250 EA 3 500 1,500 LF 180 10 1,800 LS 1 5,000 5,000 E^ 2 4,000 8,000 Estimated. Construction Cost 5%Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $42,980 2,149 $45,129 9,026 $54,155 2,708 $56,863 14 CITY OF FRIDLEY i i_2c.'d i i Z m 0 Z 0 Z QUINCY' AVE. ,'. 0:~ ~0 Z z L (-~ 0 z ;:;0 I t~ .,4 Z (/.) '.,,, ~ m mm I © © 6") --I 0 Z z@ ~@ m 31' 24" .,,-" 25' 31' 12' STORMWATER DETENTION POND HCKENNA PARK 15" f~ .~.~/ 29, ~ 23' 181' 281' I 4.8TH AVE. 47TH 1/2 AVE. 47TH AVE. 46TH 1,/2 I,VFi, c~ ~o o >. 03 'T .-q I Z I 0 · 0 z I e----4~ 44TH AVE ~J! 60" m mr- 152/ 45RD AVE , e_._, ,~ i-fl 24" FI MORE ST. C) 159' 168' 145' 'N. Fq Z Fq Z Z ~ 0 0 f,~ o. ~' -T-1 42" ~. - TYLER PL. ~ ~/~ ~ / ~/~ c ~ ~ ~ / ~ ,, ~ f ~ " 114' ~ ~~ , _ ~ ~',,~ .~ ~,~ ~ , ~ ~ ~ zz 0 om~ . , 15" ~ ~28' Bonestroo Rosene Anderlik & Associates Engineers & Architects Bonestroo, l~osene, Anderlik and Associates, Inc. is an Affirmative Action/Equal Opportunity Employer Principals: Otto G. Bonestroo~ RE. - Joseph C. Andedik, RE. - Marvin L. $orvala, RE. , Richard E. Turner, RE. · Glenn R. CooK, RE, - Robert G, Schunicht, P.E. · Jerry A. Bourdon, RE. · Robert V¢. Rosene, RE. and Susan M. Eberlin, C.RA., Senior Associate Principals: Howard A. Sanfbrd, RE. · Keith A. Gordon, RE. Richard V(/. Foster, RE. · David O. Loskota, RE. · Robert C. Russek, A.I.A. · Mark A. Hanzon, P.E. · Michael T. Rautmann, RE. · 'red K.Field, RE. - Kenneth R Anderson, RE, · Mark R. Rolls, RE. · Sidney R 'Williamson, RE., L.S. · Robert F. Kotsmith · Agnes M. Ring Allan Rick Schmidt, RE, Offices: St. ?aul, Rochester, ~(/iilmar ~nd St. Cloud, MN · Milwaukee, ~,~'1 Web.cite: www.bonestroo.com DRAFT FEASIBILITY STUDY FOR STORMWATER IMPROVEMENTS MCKINLEY STREET NE AND 40TM AVENUE NE COLUMBIA HEIGHTS, MINNESOTA BRAA FILE NO. 33208 This report presents the results of our stormwater improvements feasibility study for the McKinley Street NE and 40th Avenue NE area. Damaging floods occurred here on July 1, 11, and 13 of 1997, though resident surveys indicate that intersection flooding is a regular occurrence. We have completed our analysis of this area according to the plan detailed in our scoping study of 11/25/97. This report begins with an introduction to the problem area, followed in sequence by the following sections: Analysis and Results, Alternatives, Cost Estimates, and the Recommended Alternative. A location-map and report figures are at the end of the report. Please note that elevations are in the city of Minneapolis datum, followed in parenthesis by the USGS datum. The USGS datum is obtained from the Minneapolis datum by adding 710.3 feet. 1. INTRODUCTION As stated above, flooding occurred here for all three of the large July 1997 storms. Several homes on 40th Avenue NE, north of the intersection with McKinley Street NE, were flooded by stormwater that rose up to 2.5 feet above the street catch basins (see Figure 1). Our discussions with residents and City staff indicate that flooding is a chronic problem here, even for events smaller than those encountered in July of 1997. 2. ANALYSIS AND RESULTS We analyzed the pipe network upstream and downstream of the flood prone area (see Figure 2). Runoff from a large area, including Hart Lake and portions of Minneapolis and St. Anthony, converges at this intersection via the storm sewer network. We 2335 West Highway 36 · St. Paul. MN 55113 - 612-636-4600 - Fax: 612-636-1311 delineated these inputs and entered them into our computer model. Additionally, we located and characterized sources of overland flow such as overflow from catch basins on McKinley, Cleveland, and 39thl/2. The tipping bucket rain gauge at the public works facility indicated that the July 1 storm was the most intense of the three July storms, With over 3.64 inches of rain in 3.5 hours and 2.9 inches in the first hour. Our model, developed With the XP-SWMM32 software, simulated the July 1 storm and supports the anecdotal evidence obtained from several residents living adjacent to this intersection. The topographic survey of this area conducted by City staff, when compared to this anecdotal evidence, indicates that the high water level (HWL) for July I was approximately 237.7' (948.0)'. Our model calculates a July 1 HWL of 237.6' (947.9') and thus shows reasonable calibration to the actual storm event. Our model indicates that pipe surcharge (the buildup of stormwater in the pipe network such that additional stormwater is held back) cannot by itself account for the water levels seen at this intersection, and that local overland' flow produces the bulk of the flooding. This overland flow travels down both 39thl/2 and McKinley to the intersection of 40th and McKinley, where it ponds until the already full pipe network can accommodate it. 3. ALTERNATIVES Various alternatives to address the flooding problem were considered. Our analysis showed that storm sewer construction to reroute Minneapolis and St. Anthony flow down Stinson Boulevard to Silver Lake does not significantly lower the HWL at McKinley and 40th. We did find that a trunk size pipe from McKinley and 40th to Silver Lake would be effective. This line could run from the intersection due north through backyards or, alternately, could run east to Stinson Boulevard from where it would travel north to Silver Lake. In either case Minneapolis's and the bulk of St. Anthony's stormwater would continue along their present route. Our model indicates that stormwater ponding would be an equally effective alternative. Specifically, ponding in Prestemon Park could store excess overland flow, slowly discharging this water over the course of several hours. This type of solution does not require a trunk size storm sewer. These two alternatives are addressed 'in more detail below. 3.1.Alternative 1: Ponding in Prestemon Park This alternative (see Figure 2) involves excavation and embankment to form two detention basins within Prestemon Park. These basins would detain flow from Cleveland, 39thl/2, and McKinley. This alternative requires reconstruction of street grades at the intersections of Cleveland and 40th and Cleveland and 39thl/2, and along McKinley near the I~ark entrance. This reconstruction involves additional catch basins and pipe to convey flow into the detention basins. We propose intersection reconstruction at Cleveland and 40th so that overland flow from the north and west flows down Cleveland from 40th to 39thl/2 and into proposed detention basin A. Likewise, reconstruction of McKinley routes flow from McKinley to proposed detention basin B. Excavation within the park for detention basin A necessitateS removing some relatively large trees. Both detention basins would be dry between storms, and would discharge to the existing storm sewer under the park. Table 1 summarizes the flood benefits of this alternative. Table 1 Storm Summary: Alternative 1, Ponding in Prestemon Park HWL - 40tn Low Free- HWL - HWL - Rainfall & McKinley House board Basin A Basin Storm B (in) (City (City (ft) (City (City datum) datum) datum) datum) Before Improvements July 1 3.64 237.6' 0.1 NA NA July 1 3.64 236.0' 1.7 237.8' 238.3 100-year 6.0 236.02' 237.7' 1.7 238.2 238.3 After 50-year 5.3 236.0' 1.7 238.0 238.2 Improvements 10-year 4.1 235.96' 1.7 237.7 238.2 5-year 3.5 235.93' 1.7 237.3 237.8 3,2.Alternative 2: Trunk Storm Sewer This alternative involves installing a trunk storm sewer from the intersection of McKinley and 40th north to Silver Lake. Figure 2 shows a potential alignment for installation through backyards, as well as an alignment along 40th Avenue NEand Stinson Boulevard. The backyard alternative includes an estimated 750 feet of 42- inch reinforced concrete pipe (RCP), several manholes, easement acquisition, some street reconstruction, and significant restoration. Additionally, there are substantial logistical problems in cutting along lot lines directly north to Silver Lake. Routing east to Stinson Boulevard and then down Stinson to Silver Lake involves more street reconstruction but less restoration and less easement acquisition. Table 2 summarizes the benefits of this alternative (applicable to both alignments) in relation to the 100-year, 24 hour, and July 1, 1997 storms. Table 2 Storm Summary: Alternative 2, Trunk Storm Sewer Storm HWL Low House Freeboard (City datum) (City datum) (ft) Before Improvements July 1 237.6' 0.1 237.7' After July 1 236.1' 1.6 Improvements 100-year 236.0' 1.7 4. COST ESTIMATES Table 3 presents the cost estimate for Alternative 1 as described above and shown on Figure 2. Table 3 Estimated Cost: Alternative 1, Ponding in Prestemon Park Item Unit Quantity Unit Cost Price Mobilization LS Excavation and embankment, off-site disposal CY 12-inch RCP LF 15-inch RCP LF 18-inch RCP LF 12-inch FES EA 18-inch FES EA 2' x 3' catch basin EA Rip rap CY Clearing and grubbing LS Seeding and mulching, pond areas AC Trees EA Remove and replace concrete curb and gutter LF Full depth pavement reclamation SY Subgrade preparation SY Common excavation CY Select granular borrow TN Aggregate base, class V, in place~ TN Bituminous base type 31B TN Bituminous wear type 41B TN 1 $5,000 1,200 7.00 210 22 60 25 170 30 1 600 2 800 8 1,000 30 40 1 1,000 1 4,000 15 200 900 7 1,900 0.75 1,900 0.65 1,200 7 1,450 5 970 6.5 157 30 157 32 $5,000 8,400 4,620 1,500 5,100 6OO 1 600 8 000 1 200 1 000 4 000 3 000 6 300 1,425 1,235 8,540 7,250 6,305 4,710 5,024 4 Traffic control LS 1 5,000 5,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $89809 4 490 $94299 18 860 $113159 5 658 $118817 Tables 4 and 5 present cost estimates for Alternative 2 (for both the backyard alignment and the 40th and Stinson alignment, respectively) as described above and shown on Figure 2. Table 4 Estimated Cost: Alternative 2, Trunk Storm SeWer- Backyard Alignment Item Unit Quantity Unit Price Cost Mobilization LS 42-inch RCP LF 8' diameter manholes EA 42-inch FES EA Rip rap CY Clearing and grubbing LS Sod SY Trees EA Restoration LS Easement acquisition, permanent AC Easement acquisition, temporary AC Remove & replace concrete curb & gutter LF Full depth pavement reclamation SY Subgrade preparation SY Select granular borrow TN Aggregate base, class V, in place TN Bituminous base type 31B TN Bituminous wear type 41B TN Traffic control LS 1 $10,000 $10,000 750 75 56,250 4 4,000 16,000 1 2,000 2,000 30 40 1,200 1 5,000 5,000 4,000 3.00 12,000 15 200 3,000 I 20,000 20,000 0.30 130,000 39,000 0.75 20,000 15,000 450 7.00 3,150 720 0.75 540 720 0.65 468 495 5.00 2,475 330 6.50 2,145 60 30 1,800 60 32 1,920 1 5,000 5,000 Estimated Construction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $196,948 9,847 $206,795 41,359 $248,t54 12,408 $260,562 Table 5 Estimated Cost: Alternative 2, Trunk Storm Sewer- 40th and Stinson Alignment Item Unit Quantity Unit Price COst Mobilization LS 42-inch RCP LF 8-ft diameter manholes EA CB-MH 2' x 3' EA 42-inch FES EA Rip rap CY Sod SY Easement acquisition, permanent AC .Easement acquisition, temporary AC Remove and replace concrete curb and gutter LF Full depth pavement reclamation SY Subgrade preparation SY Select granular borrow TN Aggregate base, class V, in place TN Bituminous base type 31B TN Bituminous wear type 41 B TN Traffic control LS 1 $10,000 1,453 75 5 4,000 1 1,000 1 2,000 30 40 2,000 3 0.2 130,000 0.45 20,000 2,100 7 4,000 0.75 4,000 0.65 3,100 5 2,100 6.5 330 30 330 32 1 5,000 Estimated ConStruction Cost 5% Contingencies 20% Design, Inspection, Admin. 5% Capitalized Interest TOTAL ESTIMATED COST $10,000 108,975 20,000 1,000 2,000 1,200 6 000 26.000 9 000 14.700 3 000. 2 600 15 500 13 650 9 900 10 560 5 000 $259 085 12 954 $272,039 54,4O8 $326,447 16,322 $342,769. 5, RECOMMENDED ALTERNATIVE Based on cOst and logistics, we recommend Alternative 1. Both the disruption to local residents and the cost are greater under Alternative 2, while the benefit is the same as that provided by Alternative 1. The recommended alternative does not address problems of high ground water experienced in this area. The area around the intersection of McKinley and 40th had historically been a pond. This pond was filled upon development of the area, but ground water levels persist. In order to address groundwater seepage into basements, a drain tile system for this area might be required. Such a tile system would likely need to be drained to Silver Lake.' Z 0 I Frl CITY OF FRIDLEY I r-'-rr iq Z m 4-OTH AVE. ~' 12" 109' 175' Z W" EL W Z W Bonestroo Rosene nderlil¢ & Associates Engineers & Architects Bonestroo. Rosene. Anderlik and Associates. Inc. is an Affirmative Action/Equal Opportunity Employer Principals: Otto G. Bonestroo, RE. · Joseph C. Atnderlil<, RE. · Marvin L Sorvala, RE.. Richard E. Turner, RE. · Glenn R, Coo~, RE. · Robert G. Schunicht, P,E. · Jerry A. Bourdon, RI:. · Robert ~(/. Rosene, RE, and Susan M. Eberlin, CRA., Senior Consultants Associate Principals: Howard A, Sanford, RE. · Keith A. Gordon, RE. · Robert R. Pfefferle, RE. · Richard V(/. Foster, RE, · David O, Loskota, RE. · Robert C. Russek, A.I.A. · Mark A. Hanson, RE, · Michael T. Rautmann, RE. · Ted K.Field, RE. · Kenneth R Anderson, RE. · Mark R. Rolls, RE, · Sidney R ~(/illlamson, RE., L,S. · Robe~:t F. Kotsrnith · Agnes M. Ring - Michael R Rau, RE, · Allan Rick Schmidt, RE. Offices: St. Paul, Rochester, '~'illmar and St. Cloud, MN - Milwaukee, ~'1 FEASIBILITY STUDY FOR STORMWATER IMPROVEMENTS MONROE STREET NE AND 49TM 4/2 AVENUE NE GOLUMBIA HEIGHTS, MINNESOTA BRA FILE No. 33209 This report presents the results of our stormwater improvements feasibility study for the intersection of Monroe Street NE and 49th ~ Avenue NE. As detailed in our scoping study report dated 11/25/97, the intersection has been prone to flooding during large rainfall events. Please note that elevations referenced in this report are in the city of Minneapolis datum, followed in parenthesis by the USGS datum. The USGS datum is obtained from the Minneapolis datum by adding 710.3 feet. 1. INTRODUCTION The intersection of Monroe Street NE and 49th ½ Avenue NE flooded during all three of the July 1997 storms (see Figure 1). The water rose to at least three feet above the catch basins. During the July 1 storm, the runoff overflowed to the west, toppling retaining walls on its way to the alley behind Monroe Street NE. The inlet grate elevations at this intersection are at 184.31' (894.61'), 184.35' (894.65'), and 184.08' (894.38') (see Figure 2). The high water level (HWL) for the July 1 storm was estimated at 186.84' (897.14'). The lowest house elevation at this intersection is 186.60' (896.9') and occurs at 4935 Monroe Street NE. Residents have indicated that flooding also occurs at this intersection during smaller storms throughout the summer. The area that drains to this intersection includes the Central Avenue business district that contains large amounts of impervious surfaces. The runoff from this area is conveyed down 50th Avenue NE. Although the storm sewer network is laid out to convey this flow north to Sullivan Lake, most of the runoff bypasses the catch basins at Monroe Street NE and 50th Avenue NE, and overflows south to the intersection of Monroe Street NE and 49th ¼ Avenue NE. 2335 West Highwa.v 36 · St. Paul. MN 55113 - 612-636-4600 · Fax: 612-636-1311 2. ANALYSIS AND RESULTS We modeled the stormwater system using XP-SWMM32 computer software. For existing conditions, the model predicts yard flooding around the intersection of Monroe Street NE and 49th % Avenue NE for storms as small as a l-year storm event (2.3 inches of rainfall over 24 hOurs). For the event on July 1, 1997, the model calculates a high-water level (HWL) of 186.3' (896.6'), slightly lower than the observed HWL of 186.84' (897.14'). This computed HWL was determined with the assumption that all the catch basins were free of clogging from leaves and debris. Homeowners explained that these drains were partially plugged during the July storms, thus causing the HWL to exceed the predicted level. Table 1 summarizes the modeling results of several storms with the existing pipe network. Table '1 Storm Summary · .. Period . ~ * .... ., .: ~ :::~:::~"~:~: pn) ~ (City Datum).(City Da~dm) (ft) ~ . .~ (hr) 1-year 2.3 185.1' 186.6' 1.5 2.5 5-yea r 3.1 185.2' 186.6' 1.4 4.0 50-year 5.3 186.1' 186.6' 0.5 7.0 100-year 6.0 186.3' 186.6' 0.3 8.5 July 1, 1997 3.64 186.3' ] 186.6' 0.3 (3.5+) 1) Beyond the modeling period of 3.5 hours. 3. ALTERNATIVES A number of alternatives to capture and divert runoff from the Central Avenue business district were considered. These included combinations of new storm sewer and street regrading. It was found that these alternatives were very expensive and did little to reduce HWLs at the interSection of Monroe Street NE and 49th % Avenue NE. The local drainage area to this intersection is large enough such that unacceptable HWLs would still occur; diverting the Central Avenue area tended only to reduce the duration of the flooding. For this reason, the two alternatives presented below focus not on diverting runoff away from the affected intersection, but rather on conveying flows out of the intersection. 3.1 Alternative '1: Improve Catch Basins This alternative includes the replacement or rehabilitation of the existing catch basin structures at the intersection of Monroe Street NE and 49th Avenue NE (see Figure 2). Our field survey results and residents comments indicate that the existing catch basins become plugged with debris on a regular basis. The structures would be replaced with catch basin inlets that have larger curb inlets and vane grates which minimize clogging. As part of this work, localized curb raising behind the catch basins will be required. This alternative also includes the installation of a speed bump or minor road raise on 50th Avenue NE immediately east of the intersection with Monroe Street NE. This will create minor ponding at the catch basins on 50th Avenue NE, increasing the capacity of the catch basins. The catch basins will thus capture more of the runoff from the Central Avenue business district, conveying it north to Sullivan Lake. This alternative results in a HWL of 186.3' (896.6') at the intersection of Monroe Street NE and 49th ~ Avenue NE. This will provide a freeboard of 0.3 feet to the lowest home at this intersection (4935 Monroe Street NE), at an elevation of 186.6' (896.9). We recommend that the catch basins at this intersection be inspected and cleaned on a regular basis, particularly in the spring and fall. In addition, the streets draining to the intersection should be placed on a priority street sweeping schedule. 3.2 Alternative 2: Trunk Storm Sewer This alternative involves the installation of a storm sewer system from the intersection of Monroe Street NE and 49th % Avenue NE, north to Sullivan Lake. New catch basins will be installed at the intersections of Monroe Street NE and 49th % Avenue NE and 50th Avenue NE that will attach to the new system. Figure 2 presents the proposed layout of the system. Due to the topography of the area, the storm sewer will become fairly deep in some sections. Table 2 shows the effect this project would have on the HWL at the intersecti°n of Monroe Street NE and 49th ~ Avenue NE. Table 2 Alternative 2 Improvements :. HWL:=~:i:-:; Low Freeboard DrawdOwn ?~torm ~:-' ~ .':i,;~!! r~ouse, ~:~- ~! ,: ' , Time~::~ii::i~:,:! ..: :~;::~??:~?:: =:Datum)' :.Datum) (fi) ':~.-::,.~. (hr)::¥:':!i:'! Before improvements July 1 186.8 186.6 -0.2 .... After July I ' 185.6 186.6 1.02.0 Improvements 100 year 185.6 186.6 1.02.0 4. COST ESTIMATES Cost estimates are provided for both alternatives. 4.1 Alternative 1 Cost Estimate Table 3 presents the cost estimate for Alternative 1, Improve Catch Basins. Table 3 Estimated Cost: Alternative item Mobilization Remove concrete curb and gutter B618 curb and gutter Bituminous type 31B Bituminous type 41B R-3250-1 Catch Basin Traffic Control Unit Quantity Unit Price LS 1 $1000 LF 400 1.00 LF 400 6.00 TN 115 30 TN 115 32 EA 6 350 LS 1 500 Estimated Construction Cost 5% contingencies 20% Design, Inspection, Admin 5% Capitalized Interest TOTAL ESTIMATED COST Cost $1000 400.00 2,400 3,450 3,680 2,100 500 $13,530 677 $14,207 2,841 $17,048 852 $17,900 4.2 Alternative 2 Cost Estimate Table 4 presents the cost estimate for Alternative 2, Trunk Storm Sewer. Table 4 Estimated Cost: Alternative 2 item Mobilization Remove concrete curb and gutter B618 curb and gutter Full depth pavement Reclamation Common Excavation, street, off- site disposal Subgrade preparation Select granular borrow. Aggregate base, class 5, in place Bituminous type 31B Bituminous type 41B 15-inch RCP 18-inch RCP 27-inch RCP, some over depth 30-inch RCP, some over depth 42-inch RCP Rip Rap 6' manhole, some over depth 2' x 3' Catch Basin R-3250-1 Catch Basin Traffic Control Unit Quantity Unit Price LS 1 $10,000 LF 2400 1.00 LF 2400 6.00 SY 4540 0.75 CY 3560 7.00 SY 5340 0.65 TN 3520 5.00 TN 235O 6.50 TN 375 30 TN 375 32 LF 50 25 LF 50 30 LF 600 50 LF 350 55 LF 350 75' CY 30 40 EA 5 2,000 EA 5 1,000 EA 6 350 LS 1 2,000 Estimated COnstruction Cost 5% contingenCies 20% Design, Inspection, Admin 5% Capitalized Interest TOTAL ESTIMATED COST Cost $10,000 2,400 14,400 3,405 24,920 3,471 17,600 15,275 11,250 12,000 1,250 1,500 ' 30,000 19,250 26,250 1,200 ~0,000 5,000 2,100 2,000 $213,271 10,664 $223,935 44,787 $268,722 13,436 $282,158 5 5. RECOMMENDED ALTERNATIVE We recommend proceeding with AlternatiVe 1 on an interim basis', and closely monitoring flood levels in the future. In addition, the catch basins should be regularly inspected and maintained, and the streets on the vicinity placed on a priority street sweeping schedule. In the future, particularly when Monroe Street NE is scheduled for reconstruction, we recommend looking in greater detail at the alternative of constructing a new storm sewer to Sullivan Lake. Alternative 1 provides minor improvement to the drainage system and provides a freeboard of 0.3 feet to the lowest home in the area under the 100-year design storm. This level of protection is less than the desired freeboard of 1 to 2 feet. Alternative 2 provides 1 foot of freeboard but entailsa considerable investment in storm sewer improvements, potentially approaching the value of the affected homes. o Fq ~,. i,~~ . , :, ~ ~'.~ ~ ~LL.~ ~ '__ i ! 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L- ~ ..... _ ~... , , .... __~. _ ,, ......... ,.-.-=. , ............. ~ · ~ ~- % ..... . ~..~, .. . .-.~ .._~ .... . .--~ . ~ '~'M:"..~"~/','.-. :~.-+-.-4 ::~:L' ::::z.~ ~i!~ · ,~ ......... ~_. ~_, / ...~ ....... ~ .. ,.-- _ ..... / c~., L:~;:~:l I ~ .... · - . , · r';"T.'S~-. Ir~ ~h~ :,~::~.' ~ ~ r-''~ .... - :i ~-;~'I~--4 ~ '--~::'.~ ~F::[:~i--4~'''] i 1~~i."~-~~ ..... ~-- - ' ~.D ~-. -<.-'..' . t; ~ ...... ' LU~ ~ - ~ ! , .~_. I ~ ...... ~'- i ~.,. ~-.. ~, , _ -..: / .... ~~ · ~ ~'~ ¢'~ ~ ch ~ /I ~ ~. ; ~ ~ !: ~ ~ "% i ~! i%4 L '''~'''- '-x.,.~%~ ] F ", , . c-:6~'""4'"' ':.:T'~-.~ ~ i ~ .~:'~ 7-' ........... ), ......... .~ ~ : _~ -':J [-~.~.~ ~, ', -4 ~--~ t; ~ ~'~ '~ F-,~x'~'<;qq~ '~" '~: , ~SL:~': '7~":':E-~'~ ~'/~'¢- .[~ ..:-t":"I i ,-' ' · ".' ~ i ~ ~ .... k--i ~ I -' ~." '~'~ ........ ~-. - .... ,I ~ ~~~-~ '" ! ~-r--~m~'~'-~P~_ · ~ -4.. ~' ' ; ' ' i i I~ 7/. ;t,..~,,,~ ~ ~ ~: ~ ~ : . 0 ~ ~ 0 z C) ~' I-q Z c Fq Z I'q I I SULLIVAN LAKE / ~ o ~ ~' o I~1 Z Z Z 0 ' ' PARK ~ ~ 30' ' ~1~ It , ~0" m ~ 50TH 1/2 AVE. m 50TH AVE. ~ oo ~ ~ r ~ , 0 / ~ 4935 269' o 30' 23' HARD SURFACE PARKING/DRIVEWAY PROGRESS May 1, 1998 On March 31, 1998, we mailed 381 notification letters to homeowners who were identified as lacking appropriate hard surface parking or driveways. A copy of the letter is attached. Since that date, we have had 139 homeowner contacts relating to this issue. Following is a brief summary of the contacts we have received (note that some homeowners may have called more than once or had several issues presented in the same telephone call): Request to send contractor list .................................... 42 Extension to compliance date desired ............................... 34 Financial reasons 14 Did alley 6 Planned construction related to driveway 4 Elderly/disabled homeowner requiring medical care 3 Reason unknown 3 Recent death of homeowner 1 Summer street paving issues 1 Recent home purchase 1 Other priority home repairs needed I Driveway has been hard surfaced .................................. 29 Opinions/Complaints/General Questions ............................. 17 Other repairs/upgrades recommended (landscaping to cover dirt, etc) ....... 7 Request for copies of ordinance to be sent ............................ 3 Unusual situations ............................................... 8 Shared driveway between 2 or more neighbors 2 Planning an appeal 1 Garage grade lower than alley/street - concerned about flooding 2 Platted, unopened city alley 1 Recent property foreclosure 1 Property added to list due to lack of hard surface driveway I On April 30, 1998, the next reminder letter was mailed to those homeowners who have not yet completed their driveways or parking areas. In addition, this letter was sent to 15 rental property owners who, after searching our records, we found may not have had prior notice of the need for hard surface parking through specific compliance orders. A copy of the April 30 letter is also included. Hard Surface Extension Recommendations Following are the staff recommendations for handling extension requests which am received by homeowners related to the hard surface parking/driveway portion cf ordinance #1281. Require homeowners to document the specific masons for their extension request and indicate a specific date by which time they can complete this project. Grant extension requests for which the homeowner can document a hardship of some kind related to this ordinance. Examples of hardships would include any of those listed on the previous page except "reason unknown." There may be other reasons which we would also find acceptable which have not been presented to us. Allow extensions until July 1, 1999 at the latest, although if the homeowner desires/ess than this we grant the extension for the period of time desired by the homeowner. COLUMBIA HEIGHTS POLICE DEPARTMENT TO: FROM: SUBJECT: Walt Fehst, City Manager Thomas M. Johnson, Chief of Poli~~x~ 1998 Project Safety Net Bill for 1998 DATE: May 1, 1998 BACKGROUND: In 1995 the cities of Columbia Heights, Hilltop, and Fridley began a program known as Project Safety Net. The purpose of this program is to give the police departments of Fridiey and Columbia Heights a resource to deal with juveniles who are caught out on the streets after curfew. This program allows the officer to pick up the juvenile, write a tag, and then instead of waiting for the parent or guardian to be contacted and come and pick up the juvenile, the officer takes the juvenile to the curfew center. The curfew center is located in the Fridley Community Center and is staffed by trained social workers, who supply an immediate intervention for this problem, contact the parents or guardians for pickup, give referrals and follow-up to the problem. In 1997, due to Coon Rapids and Blaine joining this service and because of grants that were obtained, our fee for the year was waived. In 1998 the bill to our city for this service is $6,000. ANALYSIS/CONCLUSION: I am recommending that we pay the fee for the use of Project Safety Net. Over the past few years numerous officer hours have been saved by using this service. Officers are no longer tied up waiting for parents or guardians and are, in fact, back on the streets of our community in a relatively short period of time. The youth of our community are also being served through professional referrals and follow-up by the Safety Net staff. The city has also benefitted from the use of the Zone, which is a program that offers entertainment and direction to our teens on Friday and Saturday evenings. The third element that we have benefitted from is the Safety Net program being in our Middle School and High School. The Safety Net staff assists with truancy and in school problems. They are an excellent referral service and assist the officers almost daily. RECOMMENDED ACTION: Direct the Chief of Police to place the payment of this bill on the next Council meeting consent agenda. Cost to be covered as follows: $5,000 from the 1998 police budget line 3050 and $1,000 to come from the forfeiture fund #265. TMJ:mld 98-148 CiTYOF FRIDLEY FRIDLEY MUNICIPAL CENTER · 6431 UNIVERSITY AVE. N.E. FRIDLEY, MN 55432 · (612) 571-3450 · FAX (612) 571 - 1287 Memorandum 03/19/98 Tom Johnson, Chief of Police- City of Columbia Heights Kevin Thomas Invoice for 1998 Safety Net Greetings, ! hope things are well for youmelf and your city. It is billing time again for ~ involved Shoed you have any ques~on' s or concerns regarding this please feet free to reach me by phone at 572-3643, or feet free to page me at 534-4732. Kevin Thomas, Fridley Police CITY OF COLUMBIA HEIGHTS 590 40TH AVENUE N.t:'., COLUMBIA HEIGHTS, MN 55421-3878 (612) 71B2-~'800 TDD 782-2806 April 14, 1997 Mr. David Mol Tautges, Redpath & Co., Ltd. 4810 White Bear Parkway White Bear Lake, Minnesota 55110 Dear Dave: Attached is the information we discussed last week in relatiOnship to the Volunteer Fire Department's request that we no longer withhold Social Security taxes from firefighter emergency pay. Included in this packet is a letter from your fm'n dated December 7, 1992, to Margaret Egan of the City of New Brighton. At the present time I would like your opinion on whether or not you feel the City of Columbia Heights should apply for a refund of the Social Security taxes withheld on our volunteer fzrefighter's emergency pay, and, ff the City should discontinue deducting Social Security taxes on that pay. I recall reviewing this when the law changed, and the reason that we withheld Social Security taxes at that time was due to the definition and amount of pay volunteer fzrefighters are paid for emergency service. It was felt that the amount we were paying our volunteers exceeded a nominal amount, and subsequently we withheld Social Security taxes. If you would like any additional information on this, please let me know, othem'ise I would like to f'md something out in the next few weeks as to what your opinion is and what you feel we should do. I am also interested in finding out about how the other cities you audit handle this, i.e., how man), withhold Social Security taxes on firefighter's emergency pay or fzre call pay. Thank you for your attention to this matter. Sincerely, "William Elrite, Finance Director 97041697 WJE:ace THE CITY OF COLUMBIA HEIGHTS DOES NOT DISCRIMINATE ON THE BASIS OF DISAJBILITY IN EMPLOYMENT OR THE PROVIBION OF SERVICES EQUAL OPPORTUNITY EMPLOYER DEPARTMENT OF THE TREASURY constituent, Mr. Robert E. Wetherllle0 Secretary o~ the Minnesota Section 3121{b)(?)(Y) o~ ~he Xn~ernal Revenue Code ~enera!ly system cf the employer uill be considered "employment" for FICA tax purposes. Section 3121(u)(2) o~ tho Code generally provides ~hat service as an employee of a State ~r l~cal gevarnmen~ Aa There ia an excep?icn to these rules ~hat may apply in this case. Under section ~121(b)(?)(£)(AAi)~ ~ho ~erm "employvnont" does not include aery!cos performed by an tndividu&l es an employee of · S~ate or local governmen~ i~ the eerv~cea are ear=hqua~a, flood, or other similar emergency. Sec=ion 3121(u)(2)(a)(li)[III) contains an identical provision for purposes of ~he medicare portion of FICA tax. ~evenue Ruling 88-35, 1988-2 C.a. 343, provides guidelines, in question end answer ~orm, concerning laotian 3121(u)(2~ ~ ~he fireflghters. Tho ~acte ~tsted indicate that a township has a small number of regularly employed firofighters. To assie~ these ~irefightars, certain residents cf the township have volunteered their services An case c~ emergency, The township keeps a record of the residents who respond to the emergency calls end periodically pays ~he volunteers a nominal amount ~or each emergency for which ~be ~olunteer per£ormed eerviees. The ruling holds that the eervic~s performe~ by volunteer flrcfighters are considered to be per£c~med on a temporary ba~io in case of emergency and are therefore not subject to the medicare portion of the F/CA tax. . £0'8 1:00'ON ~0:8 £6,2..'r, -2- some other heels the wages received may be mub~ect ~o FICA For example, the ~ecei~C o£ either on ann~al e~ipen~ or 'etan~y' ~ay ma2 result An FICA tax liability. constituen~. If you have any q~eetione or require ~rther information, please contact Ms. Ehrenber~ o£ my sta££ et (202) 566-4747 (not a toll-£xee number). ~ev. Rui. 68-35 Sincerely yours, NANCY ~. MARKS Office of the Aseoc~&te Chief Couneel Exempt Organiza~iona) ~0'~ IO0'ON ~0:8 ~6,l~ 6n~ ~O[8~g:~D£ NO£HD!~E R~N A~ CZTY N~W ~R]BHTON TEL:$3820aa Ru~ l?'g~ 8:2a No.O02 ~]~r 7, 19~2 TAOTGES, REt)PATH & CO., L TO. ATTACHMENT A · ,-.Ch'y ~ New Bri~h.t~n - · N~w Brighton, MN 55112 ~ Marga~t: If you c~ide not to wi~zhold sccial ~"uriry ~xe.s on l~ym~mU f~ "~=z:r~ hms", the Lammal Revenue Serv'i~ may ~ssess socim.1 se.;m-ity tm.xes, pemt~ ~.nd int. ere~ if t.hey ~'ide not to 'officim.l.ty" follow the position intUit, ed by Ms. $~bbaJd. keep you inform~ of say chsages in fl,is ~ Ii' you hm~ any qu~"tion$ r~gas-c~g the for~golng, feel fr~e to m3ntsat us. TAUTOES, ~PATI-t & CO., LTD. ~~p~u~, CPA r city t~at works £a" )~' G ¢t~' et' New l~rt~t~ 803 ~ Avemae ~.W. ~.11'~: 41-6005406 Ot~ ~uty 1, 1991, ~ Cit~ o£ N~,r ~,i.~j~ belC~ wi~nidi~ trI~,A (62,0%) ~ ~Lt:a,~ (I.4~4) ~ v~lTtt~r., If you have say qaemaz~ co~ t,l~, ~o~ may ~i~ct O~c..r, t~ ~ A. ~.~, FUan~ Di~c~o:, a: 612-~g-2101. OFFIC2 CODING: 101-30000-7805 10I-2 IOCG-O000 $44:)6.80 Fifth Avenue NW, New Brighton, MN TEL:65820~ RuB 17'9~ 8:2~ c/ty that /'or you No .002 July 26, 1995 FICA for Volunteer Firefighters It's no rumor.., we don't collect FICA on flr~fighter pay £or emergency services. These servi~ ~ consid~d exempt bemuse off,ir '~mpo~" ~t~. To ~:t ~ ~c employee ~d ~c City we ~lly ~se~hmd ~is ~ before pc~ng ~e ex~ion. hfformation obtained from o= auditor and the IRS helped us to d=tcrmine the a~ ~emption was allowable. Attaahments A and B contain 'these malzrials. "l~ddifionally, refimds have i~en obtained fi.om the IRS for FICA pa.vmcmts that were m~e betwe~ 1992 ~ud 1994. Th~ refunds were for both the City's share and the employees' wJth.hotd~gs. Attachment C comaim a letter requesting the refianfi for 1994 paymenu. Al the present time. FICA continues to be '~-ithheld for drill pay, training, ~.ufl mi,~llaneous duties. Also, thc monthly wage for off:ex of the Fire Deparmaem is subjoin to FICA. I hope that the enclosed materials sro helpihl, If you have other qucstionf, please contact me at 638-2102 or Patty tsaacson at 638-2106. Sine:rely, M=gm?t A, Egan , Financ~ l)irector :FAX: 5 pages ATTN: Don R. and Ed B, cc: League of MN Cities - this might be a good idea for an update article. B02 ~:ifth Avenue NW * New ~rightor% MN ~B112 · (812) 838-210'~, ;AX (612) 635-20,[4 SPI e Park ,77 oaine unds View February 3, 1997 CERTIFIED MAIL RETURN RECEIPT REQUESTED Internal Revenue Service Kansas City, MO 64999 RE: AMENDED 941's and W-2c's for 1995 Spring Lake Park Fire Dept., Inc. 1710 Highway 10 Spring Lake Park, MN 55432 Federal ID ~-41-6038888 Gentlemen: The organization listed above is filing the enclosed amended payroll tax returns for the year 1995 to claim a refund for all FICA and Medicare taxes withheld and paid on compensation attributable to emergency fire runs. IRC Section 3121(b)(7)(F)(iii) specifically exempts payments to individuals serving on a temporary basis in the case of fire, storm, snow, earthquakes, flood or similar emergency. The amended FICA taxable compensation includes all other types of pay except those emergency runs. Attached is a letter from Nancy J. Marks, Acting Assistant Chief Counsel from the Internal Revenue Service, supporting this position. The refund claim of $12,960.57 includes both the Department's contribution and the volunteers' contributions. The volunteers' withholding will be refunded to them when received by us. If you have any questions concerning this claim, please direct them to me or to my assistant, Janet Schuldt, at (612) 786-4436. Sincerely, SPRING LAKE PARK FIRE DEPT., INC. Nyle Zikmund Fire Chief Phone: 612-75(>--1-43b Fnx: b12-786, c)tb17 Emergenc).: c)11 941c January 1994) ~me Supporting Statement To Correct Information Do Not File Separately Pa0e ~ A~ch to the emplo~ent ~x ~tum on ~ich a~jus~enm a~ ~de. No. ~A~ ?Z~ g~ Z~C &~- Telephone hume)er / A Tins form r~Jppo~$ acllu~;,~nt~ to: ~k ~e ~ ~1~-786-~36 ~ Fo~ 9~ ~ Fo~ g4~-~ Form Form g4~-M ~ Fo~ 943 B ~ (0~ ~ fi~ ~th the ret~ (~ t~ ~n~ enamg C Enter t~ oate ~u o~o~r~ t~ ~s) re~ on mbs ;-~. ~f ~ ate ~k~ng ~re t~n O~ ~ I~ ~ ~e ~t <~...ar~ - ~EC~XSSR 1995 O~o~ltt~t~,p~aseexpm:n~Pa~V.). ~-1996 ~ Signature and Ce~ifJcation ~ou MUST complete t~is pa~ for the IRS to p~cess your a~justments - ove~ayments.) I ce~i~ that Forms W-2c, Statement of Co.ected Income and Tax ~ounts, ~ve been file~ (as ~e~a~) ~th the Social Secu~y A~ministration, and that (check a~propriate boxes): ~ NI overcoll~te~ income t~es for the cu~ent calendar year and all social secufi~ and Medicare t~es for the cu~ent and prior calen6ar yea~ have ~en repai~ to employes. For claims of overcolie~ed em~loy~ social secud~ an~ MeO~care ~es in earlier years, a wd.en statement ~s ~n o~tained f~m ~ch employ~ s~ting that ~ employ~ has not c~imE~ an~ will not claim refun~ or creCit of the amotmt Of the ove~oll~tion. ~ ~ aflecte~ employees have given their walden consent tO t~ allowance of this credit or refund. For claims of ovemollecte6 em~loy~ social secufi~ and Medicare ~xes in earlier years, a w~en statement ~s ~n obtaineO from each employee stating that the employee has not claimed and will not claim refund or c~t of the amount of the overcollection. ~ ~e social s~uri~ ~ an~ Medicare t~ adjustments represent the employer's share only· An afferent was ma~e to locate the employs(s) affected, but the afl.ted employee(s) coul~ not be located or will not comply with the ce~ificat~on ~quirements. ~ None of this refund or credit was withhelC from emDloy~ wages. Sign Here 1 2 3 4 SECI~ETARY S~gnature ~' Incorn~ax/Ba/ckup Withholding Adjustment 2/3/97 la) On) lc) ~ ~:~ {O~arteny returns. Withrtel0 Income Tax ~ W~tn~10 ~ ~te q~ ~. ~ual Prev~s~ Re~n~ ~o~ T~ for ~s. ~ ~ar.) f~ Pm~ ~r~ Ne~ withheld income t~acku~ w~ol~mg a~justmem. If ~ore ~an one page, enter total of all columns (d) on fi~ ~aoe only. Enter here an~ on the a~am~ate line of t~e return with ~ich this (d) W~tlqhelCl Income T~ ~lustment form is flied .......... : ........... I~ Social Security Tax Adjustment (Use the tax rate in effect 0uring the periocJ(s) correctecl. You must (m) Per~ Correctecl (Ou~lerfy returns, ~nter Olte quarter enctecl. Annual retun'~, enter year.) also complete Part IV for return Deriocis (~) wages Prev~ur, Jy Re~orte~ for 1 HARC~ 1995 10A.386.~2 2 ~UNE 1995 1!1 ,A68.52 4 DECEMBER 1995 123 8~9.91 ~ Totals.~lf mom ~n one page, be~innin~ after 12/31/90.) ¢c) Con'ecl l'aJ~J31e Wages fo~ Pt*,'x~ 86.555.19 90 ~826. la T~$ Prewous~ Re1:x~ec~ for.Penoc~ Tq3s to~ &26,176.57 3~,1,A66.99 enter totals on first page only. · 6 Net social security t~x adjustment. If more than one'page, enter total of ALL columns (f) on first page only. Enter here and on tiaa appropriate line of the return with which this form is flied . . · 7 Net wage ad}ustment, If more than one page, enter the total of ALL lines 7 on first page only. If 5(c) is smaller than 5(bi, enter difference in parentheses ............... ~ 8 Ne~ tip a~lustment, t~ more than one page, enter the total of ALL lines 8 on first page only, If 5(e) is smaller than 5(d), enter difference in parentheses ............... · For Paperwo~ Reauction Act Notice, see I~ge 3. Cat. No, ~12420 10,503.99 ) 10,503.99 ) (84,709.58) Form ~41C (Rew ~ ~..~a~'l IVledicare Tax Acljustment (Only use th~s part for return periocls beginning after 1W31/g0. Government employers please see Exception in instructions on page 3.) enter ~tate cl~e~ en~L~. ~n~al t'etuffl$. ~'~;~r ye~'.) 1995 SEPTE~E~ 1995 1995 wages anO T~DS Prevc, usiy RePon~ f~ PerccI , B6~A62,22 123~859.9! 98,531,66 ! 'rotals.~lf more than one page, enter totals on first page only. . I~ &26,176.57 3~,1 ,~66.99 N~Meciic~ret~xac~us~men~fm~re~han~nepage`en~erto~a~fALLc~umns~c~)~n~rstpage I ~ only. Enter here ancl on the appropriate line of the return with which this form is filed .... Net wage ancl ttp adjustment. If more than one page, enter the totals for ALL pages. If 5(c) is sn-~aller than 5(b). enter ¢lifference in parentheses ................... (~1 Mec~re Tax ~l~ljustment ( 606~3~) ( 73'. 52) (2,&56.58) (e~,709.58) Explanation of Adjustments SEE ATTACHED COVER LETTER SPRING LAKE PARK FIRE DEPARTMENT, INC. CONSEI~r TO APPLICATION FOR REFUND OF SOCIAL SECURITY TAXES , HEREBY CONSENT TO APPLICATION BY THE SPRING LAKE PARK FIRE DEPARTMENT, INC. FOR REFUND OF SOCIAL SECURITY TAXES THAT I HAVE PAID ON EMERGENCY FIRE RUNS FOR ;~T.~. TEARS BETWEEN 1993 AND 1995. I UNDERSTAND THAT THE REFUNDED AMOUNTS WILL BE PAID TO ME UPON THE DEPARTMENT'S RECEIPT OF SUCH REFUND. ! ALSO AGREE THAT I HAVE NOT AND WI?,T. NOT MAKE A SEPARATE CLAIM FOR REFUND FOR THESE SAME TAXES. SIGNED DATE: ! \USERS \ KA.TaT \~UCONS Z ] 1995 FIRE CALL WAGES 1995 QUARTERLY FIRE CALL WAGES 1995 ~E 71.55 0.00 0.00 0.00 71.55 FCWAGEg$.XLS Page ] 12/14 ~9612: l ] PM EDPATH & CO., LTD. CE~T~F.£~ P~/~L lC ACCOUNTANTS July 29, 1997 William Elrite Finance Director City of Columbia Heights 590 40th Avenue Northeast, Columbia Heights, MN 55421 Re: Volunteer Firefighter Emergency Pay Dear Bill: Dave Mol has asked me to respond to your letter of April 14, 1997 regarding emergency pay for volunteer firefighters. Over the past several years there has been much discussion surrounding the classification of payments to volunteer firefighters who also receive pay for routine training and other duties. Internal Revenue Code Section 3121(b)(7)(F)(iii) provides an exception to the social security tax withholding requirement for employees serving on a temporary basis in case of fire, storm, snow, earthquake, flood or similar emergency. A similar exemption for federal unemployment taxes exists under IRC Section 3309(b)(3)(D). As you have seen from our letter dated December 7, 1992 to Margaret Egan at the City of New Brighton, the Internal Revenue Service's unwritten opinion appears to be that the wages paid for emergency fire calls do meet the exception under IRC Sections 3121 (b)(7)(F)(iii) and 3309(b)(3)(D). The treasury department ruling that was issued to Jerry Sikorski in 1992, although he!pfal, is not bulletproof. Internal Revenue Service rulings are only applicable to specific cases. Therefore, the service could take a position contrary to this private letter ruling based on slightly different facts. That being said, the fact remains other cities and volunteer fire departments have been receiving refunds of the social security and/or federal unemployment taxes withheld or paid based on emergency fn'e nm wages or stipends. The statute of limitations on payroll tax returns filed on or before April 15 following the tax year are deemed to have been filed on April 15. Consequently, as of today the City of Columbia Heights would have three years of potential refunds of social security and medicare taxes. Before filing for any refunds, it would be advisable to review any other outstanding payroll tax issues,~ from those years with which the City may have tax exposure. Filing of amended returns wj&l extend the statute of limitations on these tax periods. ~ '~' - Bear Parkway · White Bear Lake. Minnesota 55110 · 612,'426-7000 · FAX.,'426-5004 · Member of HLB International City of Columbia Heights July 29, 1997 Page 2 If you are concerned with potential IRS attack on the refund claims subsequent to the refunds, you may wish to escrow the refunded taxes for a period of time as insurance against such claims. We are currently involved in an IRS audit of wages paid to volunteer firefighters with slightly different facts (i.e. they are a private non-profit fire department). We will keep you updated as to the outcome of said audit. If you have other questions or require clarification, please call us. Sincerely, TAUTGES, REDPATH & CO., LTD. Paul W. Longsdorf, (7,2jPA PWL/tle