#13 - Impervious Surface Text Amendment

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Thanks for providing the opportunity to comment on these proposed changes. The Valley Branch Watershed District considers the water surface of a pool an impervious surface, butVBWD doesn’t consider a pool a structure. These VBWD definitions require stormwater management andvegetative buffers be considered with pools but minimum elevations are not considered. While unclear, it appears Lake Elmo considers a swimming pool a structure. (City definition of structure isanything constructed or erected on the ground or attached to the ground or on-site utilities, including, butnot limited to, buildings, factories, sheds, detached garages, cabins, manufactured homes, signs, recreationvehicles not meeting the exemption criteria specified in LEC 100.00.090(c)(1), and other similar items.) If aswimming pool is considered a structure by the City, it appears the City would require the lowest elevationof pool to be at least 2 feet higher than the adjacent public water’s 100-year flood level based on Table 17-3of the City’s Shoreline Management Overlay District code. Is this the City’s intent? If not, the City mightwant to specifically exempt swimming pools from the minimum floor elevation requirement. Has the City evaluated the implications to water resources with the proposed change in maximum amountof impervious surface coverage? Why is 25% being proposed? The proposal would allow more impervioussurfaces to unsewered areas around Lakes DeMontreville, Olson, Jane, and Elmo. These lakes are the jewelsof the many lakes and ponds in the City. Increases in impervious surfaces without thoughtful mitigationcould negatively affect these lakes. As the City reviews its requirements, I suggest that the City consider requiring the bottoms of septic tanks,drain fields, etc. be at least 2 feet higher than the adjacent water’s 100-year flood level. Perhaps City codealready requires this based on the City’s definition of structure. Thanks, John John P. Hanson, PE Valley Branch Watershed District Engineer Barr Engineering Co. | 4300 MarketPointe Drive | Bloomington, MN 55435 office: 952.832.2622 | cell: 612.590.1785 JHanson@barr.com | www.barr.com | www.vbwd.org From: Ben Hetzel <BHetzel@lakeelmo.org> Sent: Monday, July 18, 2022 3:49 PM To: Marty Powers <MPowers@lakeelmo.org>; Jack Griffin <Jack.Griffin@focusengineeringinc.com>; 'Scollan, Daniel (DNR)' <daniel.scollan@state.mn.us>; John P. Hanson <JHanson@barr.com>; karen.kill@mnwcd.org; mmoore@ciwoodbury.mn.us Cc: Molly Just <MJust@lakeelmo.org> Subject: Impervious Surface Zoning Text Amendments CAUTION: This email originated from outside of your organization. All, The City of Lake Elmo has self-initiated zoning text amendments in regards to impervious surfaces. I have