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Home My WebLink AboutGrading Plans - 05/01/2023Architectural Structural Geotechnical Stephen Agenbroad, CEI Developn�tent Review Engineer Water Utilities Engineering City of Fort Collins 970-221-63 3 9 sageilbroad cni,fcgov.com Re: Myrtle Street Drainage 1318 Myrtle St Fort Collins, Colorado Dear Stephen: Engineers / Architects Materials Testing Forensic Civil/Planning Grading/Stormwater Plan Accepted 4/30/23 (Building Permit Released) Revised Accepted by: sagenbroad Date: 05/01/2023 RMG Job No. 192562 Thanks for your comments and observations on this difficult site. As you noted, this 0.022 acre residential lot in Old Town was not designed to allow new drainage to the Alley. Plus the Alley and the Street are above the back yard. Requiring a pump if that were the only solution. The Existing Home, Carport, Shed or one car garage and the existing gravel parking area at the Alley mostly drain to the back yard. The four existing lots to the west also drain to this lot's back yard. Then the entire back yard drains east Lot to Lot down the block, through the back yards. Some portions of the Existing impervious areas do drain directly to the adjacent right of way in Myrtle Street or to the alley. But that is inarginal. You and I discussed a Retention or Detention area in the back yard. A good idea in principle, but it would have to be sized for the offsite flows from the four lots to the west. It appears to me to best NOT DISTURB THE HISTORIC DRAINAGE PATTERNS. IE Continue to allow the back yards to absorb as much as they can and continue to overflow when necessary from lot to lot. I have directed all of the additional impervious area (the new garage) into a depressed garden bed in the back yard. This should maYimize the infiltration of the additional runoff from the garage roo£ This increased the total onsite impervious by 5%. (Summary table on the map). When added to the flows from the west it is less than 5% additional impervious. If there are reports of drainage complaints in the area, siinilar landscaping buffers could be constructed along the west and east fence lines. I hate to call them detention areas or even rain gardens because I do not wish to create the impression of a point discharge to the adjacent lot. Trying to stay as low iinpact and dispersed as possible. Southern Office: Central OfCice: Northern Office: Monument: 719.488.2145 Colorado Springs, CO 80918 Iinglewood, CO 80112 Windsor, CO 80>50 Woodland Park: 719.687.6077 719.548.0600 303.688.9475 970.330.1071 rmg-engineers.com 1318 Myrtle St Fort Collins, Colorado I ask you to approve or approve with conditions the attached drainage plan at your earliest convenience. I hope this provides the information you have requested. Should you have questions, please feel free to contact our office. Thank you again for your help on this site. Respectfully, RMG — Rocky Mountain Group Lester Crawford, P.E. Sr. Civil Project Manager 970-773-0610 CC: Recycled Properties LLC 1298 Main St # 41�1 Windsor, CO 80550 RMG — Rocky Mountain Group 2 Job No. 192562 Graphic Scale 0 15 30 60 � �PROPERTY LINE I DOWNSPOUTS (2) � ] 2� p� I�DRAIN TO 9EPRESSED � GARDEN/LANDSCAPING BED .._i ; DRIVE WAY oi - � 1 PROPOSED EXISTING 20X24 GARAGE N SHED/GARAGE � ExisnNc 22.�� CHAIN LINK GATE �_ /�///,� � I EXISTING DRAINAGE FLOWS EAST — LOT TO LOT— � UNABLE TO DRAIN TO HIGHER STREET OR HIGHER ALLEY S� 33 �� Y EXI5TING HOME � � 0 a � U � IMPERVIOUSNESS LOT AREA 9,501 S0. fT. IXISTING IMPERVIOUS 3,306 SQ. Ff. 35R NEW IMPERVIOUS 4$0 SQ. FT. SR NEW TOTAI. IMPERVIOUSNESS 3,786 SQ. Ff. 40% Architecture Materials Testing Structural Forensics Geotechnicai Civil / Planning Engineers / Architects NORTHERN COLORAD� OFFICE 7292 GREEIJRIDGE ROAD. LJNIT 708, WINDSOR, C❑ 8055❑ f97�1 330-1071 - WWW.RMGENGINEERS.C�M 50UTHERN COLORADQ, DENVER METR�, NORTHERN COLORADQ MYRT�E STREET A��EY 511NG 19.1' GRAVEL i crsun maun uz — g�T� � � at��MOa�riiat�waA�r• roww�r ewouwa s.o re�a ❑ oasnw smwn�xaw . .. oon.n mxxic n�wort E1081M0 Al�NLT PA�fliM� � FN41�10 WmCMm ME� � �� ,�,.,� �i��i � � „� .�,��e 0 ��..,� .. PI10P0� A4MLLT P�tfltNi � i'11OV.� INaSMD IIIFA 2�n PPTO�pl2lEtllAlO W/IL ��''�' PR�n 1 S �l�1KN1 ��;:�� R�.; F'� ; .:,�F, 9%�,. �S :,� 4130/2023 �: �„ 31480 �. NOTE: EXISTING PROPERTY DRAINAGE PATTERNS DO NOT CHANGE. MYRTLE STREET GARAGE DRAINAGE PLAN 1318 W MYRTLE ST. FORT COLLINS, CO 80521 RECYCLED PROPERTIES LLC. JOB No. SHEET No. DATE: REVISION: ENGINEER: ORAWN: 192562 1ot1 04-30-23 LGC RMK