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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. t a .r z� �1�11111 .•+3w - Illlll�t_._:______ylllllllll _ „�,',t •f. - Illlllllllillllllllllllllll . 'y• ._ _ �� IIIlilllllllllilllllllllll ��y�-� - Illlla!•�I111lIIIIIIIIIIIII Illlilllllilllilllllllllll' ji%• ��-.. IIIIIIIIIIIIIIIIIIIIIIIIII i for - OK IIIIIIIIIIIIIIIIIIIIIIIIII • �� .. ,. I I I I I I I I I I I I I I I I I 14 eIel 1 [el re muse :..l AVOLoIe e