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Home My WebLink AboutGrading Plans - 03/24/2020- - t _ �- .� �. • ' Engineers Planncrs Survcyors Geotechnical �A ,'' ji Landmark � _ . September I 9, 20 I 9(Revised I/27/2020 & 2/ I 4/2020 & 3/ I 9/2020 & March 23; 2020) Project No: SNYDEL- I 9H I D-28-307 I ov.�l-!r•d 97Q-��i-6�85 'cl: Fr�� 866-3?9-52�= �ax ?7J-e5'-5298 DRAINAGE MEMO Ww�� North %z of Lot 3, Block 72, Fort Col�iqs �,�ubdivis4on z,_ (a.k.a. 209 South Sherwood Street), Fort Collins, CO B1912297 Memo & plan accepted To Whom It May Concern, and permit released 3/24/2020 DJM The purpose of the grading plan for the address referenced above is to protect t e propose detached garage with shed structure at the rear of the lot, the existing residence at the front of the lot, and adjoining lots from stormwater runoff. The existing subdivision for Fort Collins was established around approximately 1880. The grading for the area in this subdivision will never be able to meet the current drainage and grading standards. This lot is configured as a "Type B" grading which allows for drainage to flow both to the front and rear of the lot from some established high point. The existing side lot lines on the north and south of the lot are relatively flat. The south side lot line near the rear where the garage will be added is less than 0.5%. The north rear lot line has a low point that is approximately 40' east of the northwest lot corner and is about 1.6' lower than the corner. However, there is a high point along this side yard lot line that is approximately 80' from the lot corner or 40' from the low point and is about I.I' higher than the low point. It appears part of the site storm runoff currently exits the property at this low point and flows across the neighboring property and makes its way to the alley behind both properties. It is proposed this backward runoff continue as it has historically occurred. These are existing established drainage patterns along the lot lines and alley to the west. These grades cannot be changed without impacting other residences and the adjoining alley. The alley drains from north to south with a relatively flat slope to the south of the property. The proposed garage will add a small amount of stormwater runoff to the alley at the southwest corner. It is recommended gutters be installed on the proposed structure. Downspouts should have extensions and be required to discharge to the west and south towards the alley since this is the direction of historic storm-water flows. The proposed garage is located in the City of Fort Collins Flood Fringe based on the map provided by the City of Fort Collins. We have worked through the City of Fort Collins Flood Plain Management Department and have received approval on the plan. Since there will be no habitable space in the lower garage level, the Flood Plain Management Department allowed the garage floor elevation to be below the Base Flood Elevation (BFE) of 5,004.48 (NAVD88) since flood vents were provided. In addition, all mechanical equipment is required to be installed above the Regulatory Flood Protection Elevation (RFPE) of 5,005.98. This Drainage Memo will address the Stormwater Department concerns. The current lot is 9,485 sq. ft. and contains a front side walk (56 sq. ft.), front porch (80.5 sq. ft.), house ( I 472.5 sq. ft.), and at the rear of the lot a patio (520 sq. ft.) and a shed (80 sq. ft.), leaving 7,276 sq. ft. as grass. The patio and shed are to be removed equating to 600 sq. ft. It is proposed to add a two-story garage (484 sq. ft.), an exterior stairway access ( I 54 sq. ft.), with driveways (285 sq. ft.). The total new construction area will be approximately 923 sq. ft. Therefore> the net increase in impervious area is approximately 323 sq. ft. � Doug Bennett at Stratton Homes Drainage Memo — 209 South Sherwood Street Fort Collins, Colorado Project No. SNYDEL- I 9H I D-28-307 Page 2 of 2 Landmark Based on the areas and information provided above, the addition should not substantially change the historic drainage of the surrounding alley and properties. The site drainage should not impact the proposed structure or adjacent properties. Stormwater runoff from the yard, will follow the historic drainage paths and flow around the proposed structure on either side and will reach the historic discharge points at the alley. It is not proposed to change the mid- yard runoff along the north lot line that historically flows through the north lot line low point and then to the alley. This will continue to follow this historic flow path. The remainder of the site stormwater flow will discharge to the alley as has historically occurred. The top of foundation, adjacent finish grades, and spot grades and elevations shown on the Grading Plan and the information in this memo should be used to perform the final grading for the site. If you have any questions, please feel free to contact our office. Sincerely, LA DMARK ENG EERING, LTD. � Rodn A. Harr, P.E. Director of Engineering attachements v/ . -- 3�3- /�� /r .��v � � �,' , , .. ��A-' ir.`'•, �///(i'i� lli��\11\�' > > ; PLOT PLAN NORTH 1 /2 OF LOT 3, BLOCK 72, FORT COLLINS 209 SOUTH SHERWOOD ST. FORT COLLINS, COLORADO EXISTING LOT AREA 9485 FT` HOUSE 1472.5 FTZ FRONT PORCH 50.5 FT� FRONT WALK 56 FT2 TO BE REMOVED PATIO 520 FT� SHED 80 FTz TO BE CONS7RUCTED NEW GARAGE 484 FTz NEW STAIRS 154 FT2 NEW DRIVE 285 FTz �L._'� �?— SOUTH SHERWOOD STREET NO' 00' 50"W 49.82' N � m � � � r� N lf J � ro Z N ii W 0 � w � I I _ (14,02( 2'L.00' 14 WALY 56 FTZ 9,485 SQ FT IORCH 80.5 FTZ i I � I � I � � � � � EXISTING I HOUSE 1472.4 FT2 � � � � � � � � � I I I � � � � � � O IN � I i � I � I I � I I 4_02' 7 3.97 � 2z.00' I . PROPOSED . � � r a -�f�Jsc,€ — o � c�i F.F.=03.� cv I � N F.Ci.=d.z� N � I � �>- I. Fr o, ,,� ¢ o i„ ¢ _� _ a � �w —�� -�3�.l o �� o� I� p� 80 FTZ w SO' 07' 46"W 50.03' ALLEY SNYDER LAND SURVEYING INC. PROFESSIONAL LAND SURVEYOR ERIC JAY SNYDER; PLS 38555 0: 970-686-5157 C: 724-992-8754 E: SNYDERLANDSURVEYING60UTLOOK.COM W: SNYDERLANDSURVEYING.COM � �iF 2 0 ��o� x� o h�� qx �` �qF�.FW r~?� q �N� ��W�� w�� [w.N Qr��,>WW [`�,�y� t�a, ��a q�"iCcjC�-� p�� o j�q o��''�� `�> � `�� '�a� � � w0 W F'+'� C<Vj�� V k' � Ci F-� C�-� p�" �l �Y � o o� W v�� a 42�0 \��' � �"� �o��Q !� wa� w �� 'aqw a �� oww ��a ;w � �ti� w 0.aw Q�N�� cn r�� -7 �i�2r�v� � �� ti2� ��w�� °� WW� � 2"�'� vW��F. � Ul Ev �/7 Cx� ��Y • h N q�'�U � qw� �� g e� � � q ��w� " yr�`'� ��y �o� F,.~2�,��a O ~ � `Y �] � �Y ~ � �' � � w � Q � � � � � � ^ I r � � z�F � �a2 �2w�� `Y o'��', W W� r�i, '�2 e 0.' �� o-a� a. �w� �� o x �.,WU �q�� ?�. cY,� h Cy � � 7 � ��' q w�z o��x� w�x � ��w>"0.��,�0 � F' � y��W�w�� 2 Q x��v�� Z ��xoqw2�� a��qF`Wo� � �OF.� F.ti��'fxl �f� F' N�ti � �ti�V�w ��e¢� �E`�tiryEw-.o,qr� �t��,ww� ��7��o � 0.� � Q' Uw�w vo�'�0. pwZo �n � W Ui �W�Wo�qwFe�aA��UFo ti 2QA a� x N�zv� � ��2 o e � N �.ww �� o�e�i��av�n�i Q�4� o EXISTING SHED TO BE REMOVED STRATTON CUSTOM HOMES nne: SITE PLAN DA7f: 12/9/2019 �oe "°: STRA-19-08-017 SCALE: 1 "=20'