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Home My WebLink AboutGrading Plans - 01/06/2022 (2)December 15, 2021 Grading/Stormwater Plan Accepted Dari MOgeri, P.E. (Building Permit Released) City of Fort Collins Utilities — Stormwater Engineering Accepted by: Dan Mogen 700 Wood Street Date: 01/06/2022 Fort Collins, CO 80521 RE: 501 Edwards Drainage Memo Residential New Single Family Detached Permit Number B2104824 Dear Dan: This letter has been prepared to summarize the drainage concept and changes for the existing property at 501 Edwards Street. The existing single family detached residence will be demolished and replaced with a new single family detached residence. Existin� Draina�e Patterns The existing single fainily detached residence at 501 Edwards Street is bound to the north by Edwards Street, to the west by Whedbee Street, to the south by the public alleyway, and to the east by a single family residence at 503 Edwards Street. The existing site consists of an approximately 800 square foot residence, sod and a large gravel parking lot. The current drainage pattern drains to the north, west and south away from the eXisting building at approximately 2% to 5°/o. The site lies within the Spring Creek Drainage Basin and has an overall weighted imperviousness of 37.4% as per the following breakdown: Rooftop: 811 ft2 at 90% Concrete: 53ft2 at 90% Gravel: 3,219ft2 at 40% Landscape (C/D Soils): 1,525ft� at 2% Total Area: 5,608ftZ Weighted Imperviousness: 37.4% The site is located in FEMA Flood Zone X, area of ininimal hazard, per FEMA Flood Insurance Rate Map number 08069C0979H, effective date OS/02/2012. Pronosed Draina�e Patterns The proposed drainage patterns are to reinain the same as the existing drainage patterns. In general, the proposed redevelopment of the site consists of a new single-family residence to replace the existing house in approximately the same location along the north side of the site. The drainage patterns will reinain the same, mostly draining to the north, west and south. The downspouts on the new house will discharge into landscaping to provide a landscape buffer prior to entering the curb and gutters in Edwards Street and Whedbee Street. The new site will have an overall slight reduction in imperviousness even though the new house will be larger than the existing. The new site imperviousness will be 37.2% with the following breakdown: 501 Edwards Street Drainage Memo December 15, 2021 2 of 2 Rooftop: 2,090ft2 at 90% Concrete: 153ftZ at 90% Landscape (C/D Soils): 3,365ft2 at 2% Total Area: 5,608ft2 Weighted Imperviousness: 37.2% The gravel parking area shown in the drawings is an interim condition, ultimately a 600 square foot garage will be built in the future. The garage is not a part of this project at this time. Therefore, the garage and a small concrete drive has been included in the calculations to show the ultimate condition. To the maximum eXtent practical, this project has implemented landscaping buffer zones and minimized directly connected impervious areas to improve water quality runoff, promote infiltration, and reduce peak runoff volume. Erosion and Sediment Control During construction, temporary erosion and sediment control practices will be used to limit soil erosion and sediment discharge off the site. In our professional opinion, the development of this project will have no adverse impacts on the surrounding developments. Please feel free to contact me to discuss any questions you may have. Sincerely, �,� By: N ` Erik T. Nakos, P.E. QP'�� REG�S V��O ��\S�,�T, �� `f� �� 40776 00�..12/15/2021 .: �� ss��NA L ��G y� �,� a,e.�� P� �e,�� 6SLL�6£5-80£ 3Nb'l i1330 311HM SLZO F�I�OS � QC1V 11 bZSOB O� `suill�� o� ' �� i_ �aa.��c� sp.��Mp� I OS 'il , � �aa,��S p.��nnp� - �MN i i �,�a�3,�� ilq �: (.`. _ d0 �� 8 e\ �� [Oh �g:.�..:�� F W � � A � � w � � � � � ai � w �� «i d rn : � ' `� � C� ,� �i° Z� �—� ! .L.�.�U.LS .��AQ�M c ca a � xzw � � , c o — � � = �x�� C7 ,J � Qoc� � , 0 � � � � 4 �i � Q I � ---- -----� eY �^, . ,��' � � � Z p < � — �° Crr� � � � > J � � I W j _ .. L � y � : _ �N ,`�, L �--� - 4,< .`�ciOp s` I - �" �Ou � � I ,900tIM„S'c CC EN)S .,' I ..:a �,� h � ; -r-I�� --''�---r - --�'�,= � ��- , ��w � 15� � I ' ,= � � � �L I__�_ y. - � � J I� � j I I,�____ 7 LL �=� � - � -- --�,--- �� — --------- �' LL�OECM.�Sc,Lc..OUS / � � � � � � � � � � i I � � � � � _ `' .L��U.LS �.�g�3M � =U °� `� u, .