5.a 4 Appendix C - Woolford_Phase A Hydrology ReportWestwood
MEMORANDUM
Date: March 9, 2017
Re: Woolford Community Solar Garden — Desktop Hydrology Study
File 0011629
To: Minnesota Solar Connection
From: Joe Fox, P.E., Water Resources Engineer
7699 Anagram Drive
Eden Prairie, MN 55344
Main (952) 937-5150
Fax (952) 937-5822
westwoodps.com
(888) 937-5150
The Woolford Community Solar Garden project is a proposal to build a solar array and
appurtenant infrastructure on a site along Manning Trail North in the City of Scandia,
Washington County, MN. The site is 8.5 acres. The solar array will generate 1 MW.
Jurisdictions and Regulations
The site is in the following jurisdictions
State of Minnesota (NPDES permit)
Washington County (No specific stormwater regulations)
City of Scandia (No specific stormwater regulations; see City of Scandia
Development Code, Chapter 2, sections 3.6 and 3.7)
Comfort Lake Forest Lake Watershed District
o Discharge rate control for 2, 10, 100 year events
o Volume control for 2 year event
o Decrease total phosphorus load in runoff by 50%
o Solar Panels are not considered impervious)
Hydrology
Currently the site is used for agriculture. It is located on a local high point with a small
section of offsite runoff coming into the northwest corner. Runoff drains to the
northeast and to the southeast. To the northeast, stormwater flows toward a wetland
which then drains to Bone Lake. To the southeast, water drains to a small pond; any
discharge from the pond would drain to Nielson Lake. The middle of the site is
relatively flat with slopes up to 6.5% along the south and east boundary lines. There
are no low spots or deep channels within the proposed project boundary. There does
not appear to be a need for culverts, low water crossings, or any other stormwater
infrastructure.
' Conversation with Emily Heinz from the Comfort Lake Forest Lake Watershed District on March 9,
2017.
Multi -Disciplined Surveying & Engineering
TBPLS Firm No. 10074302 westwoodps.com
March 9, 2017
Page 2
The NRCS Web Soil Survey shows B soils for the site, which means infiltration is
possible. However, soil borings from the site will be required in order to get accurate
soil information.
The site is within a FEMA Zone X, which means it is not in a 100 -year floodplain.
Further hydrologic analysis should include stormwater modeling of existing and
proposed conditions in HydroCAD. This would show whether the site meets the
watershed district's regulations. As mentioned, soil borings are also required to get an
accurate description of site soils.
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