HomeMy WebLinkAboutContract No. 2013 2494 (/s1
A
WSB
&Associates.Inc. engineering-planning-environmental•construction 701 Xenia Avenue South
Suite 300
Minneapolis,MN 55416
Tel: 763-541 4800
Fax: 763-541-1700
February 27,2013
Mr.Kevin Hansen
Public Works Director
City of Columbia Heights
636 38th Avenue NE
Columbia Heights,MN, 55421-3835
Re: Scope of work to prepare a Jackson Pond Feasibility Study
WSB Project No. 01792-070
Mr.Hansen:
We are pleased to provide this scope of work to prepare a water quality focused feasibility study for
Jackson Pond. Previous Jackson Pond reports focused on the pond's flood control features and only
developed minimal water quality aspects to the pond rehabilitation project. This new look will focus on
expanding the water quality performance of the project while maintaining the project's flood control
performance, as developed in previous analysis.
The City prepared a feasibility study in 2008 to improve flood control function at Jackson Pond and has
installed storm sewer pipe near University Avenue in preparation for a Jackson Pond project. The
feasibility study recommended a project whereby Jackson Pond would be converted to a dry pond,thus
increasing available flood storage. A small pump would lower the pond below the current gravity outlet.
Water quality modeling determined that the conversion to a dry pond with highly restrictive 1-cfs low
stage outlet had little impact on the pond's TSS and TP removal.
The purpose of this feasibility study is to consider additional project features that would reduce runoff
volume and/or phosphorus discharge to the Mississippi River via this pond.
Below we list the tasks necessary to complete the feasibility study.
Task 1: Hydrologic and Water Quality Analysis
Based on drainage area delineations and land use,we will calculate annual runoff volume,TP,
and TSS loading to Jackson Pond and the loading passed from Jackson Pond to the Mississippi
River. We will do this for existing conditions and then compare this to existing MWMO
Minimum Standards.
The preliminary design for Jackson Pond consists of a small "off-peak"dewatering pump. Given
this design,there will be a significant amount of annual runoff captured below the gravity outlet.
This runoff can be routed to an off-site treatment BMP or to an area where it could be used for
irrigation,such as Huset Park. Depending on the types of BMPs considered,we will calculate
phosphorus,TSS,and volume load reductions within the Jackson Pond drainage area and the
resultant decrease to Mississippi River loadings.
St.Cloud• Minneapolis•St.Paul
Equal Opportunity Employer
wsbeng.com
Mr.Kevin Hansen
February 27, 2013
Page 2
We will not re-quantify flood control benefits since this was adequately covered in the 2008
feasibility study and conditions on the ground have not significantly changed. We will
summarize the results of the previous study in the new feasibility report,however. The report
will emphasize that any potential project that frees storage in the Jackson Pond and the Huset
Park pond(such as a recycling for irrigation project)would benefit downstream flood-prone areas
in Minneapolis.
Task 2: Alternatives Discussion
We will discuss alternative projects and their potential to provide pollutant reductions to the
Mississippi River via Jackson Pond. Alternatives might include water recycling for irrigation,
augmenting in-pond extended detention,consideration of upstream BMPs,using structural BMPs
or iron enhanced filters in the Jackson Pond area, and searching for more effective downstream
BMPs. It is necessary to explore the alternatives so that there is reasonable assurance that the
most cost effective project stands out. We will also discuss any impact on habitat and vegetative
cover in converting the existing wet pond to a dry pond.
Our alternatives discussion will provide descriptive narrative,pollutant reduction calculations,
and planning level cost estimates for up to four feasible alternatives. We will also discuss
maintenance issues with each alternative and will include ongoing maintenance and operations in
a present worth comparison of the four alternatives. Only the recommended alternative will be
brought forward to task 3.
Task 3: Preliminary Design and Feasibility Report
We will develop the recommended design and quantify the water quality benefits based on
existing loadings to Jackson Pond.
To support our narrative description,we anticipate including an overview map,two plan view
sheets showing improvements at Jackson Pond and downstream if the recommended project
involves facilities in some other location. We will also provide a detailed excel spreadsheet
showing the water balance and pollutant reduction calculations.
Permits and approvals are required for this project and we will outline these in the feasibility
report. We have already discussed the project with the Minnesota DNR and U.S.Army Corps of
Engineers so we have a good understanding how the project fits within their permit processes.
Other permits include an MPCA construction permit, and a permit to dispose of contaminated
sediments if these are encountered.
Task 4: Project Management
Project management tasks include a kickoff meeting and one other meeting or council
presentation,depending on City and Watershed Staff preferences. We will also be requesting
certain files from the City including GIS shape files of land use and drainage areas,storm sewer
base mapping,and aerial photographs. Project management tasks also include regular progress
updates via email and descriptive and promptly submitted invoices.
Mr.Kevin Hansen
February 27, 2013
Page 3
We can complete the feasibility study within four weeks of authorization as long as data we request is
provided within a couple business days. We propose compensation on an hourly basis not-to-exceed
$13,600. I will serve as project manager on the feasibility study. Technical analysis will be conducted
by Earth Evans and/or Paul Hudella,with my assistance. If you have any questions about this scope,
please call me at 763-231-4876. We have included a signature block for City authorization to proceed.
Sincerely,
WSB&Associates,Inc.
Bob Barth
Senior Project Manager
I hereby authorize WSB&Associates, Inc. to proceed with the above-referenced work.
Signature Dxfe
Authorized Representative,City of Columbia Heights
s � r
g1 ��
Printed Name
Title