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Home My WebLink AboutFORT COLLINS JEEP - PDP - PDP170013 - CORRESPONDENCE - DRAINAGE RELATED DOCUMENT�' F �'ARA CTC�,ti : �1��GIN�ERING CO ,�' �'�, "1'ANI ;S', INC,'. DRAINAGE CONFORMANCE LETTER Fort Collins Jeep Dealership 224 West Harmony Road Fort Collins, Larimer County, State of Colorado March 9, 2017 Shane Boyle City of Fort Collins Engineering Department 281 N. College Fort Collins, CO 80524 970-221-6339 sboyle@fcgov.org Re: Proposed Fort Collins Jeep Dealership Dear Mr. Boyle: This letter is written to state that the approved drainage patterns for the proposed Fort Collins Jeep Dealership, conforms to the original drainage provisions for the site (constructed in 1974.) Fort Collins Jeep Dealership is located on a site currently containing 4.48 acres northwest of the intersection of South Mason Street and West Harmony Road in the City of Fort Collins, Larimer County, Colorado. The site lies in the Southeast % of Section 35, Township 7 North, Range 69 West of the 5t`' Principal Meridian. It is bounded on the north by an existing car dealership (Pedersen Volvo), on the east by South Mason Street with existing commercial development beyond, on the south by existing West Harmony Road, with existing educational development beyond, and on the west by existing bus road, with railroad with existing railway, greenbelt and residential area beyond. Soils on the site, according to USDA National Soil Conservation website, consist of Nunn clay loam- Hydrologic Soil Type C(94% of site) with a small area of Altvan-Satanta loams (6%) — Hydrologic Soil Type B, in the northeast corner of the site. Fort Collins Jeep Dealership is located outside the 100-year floodplain, according to FEMA FIRM map panel 08069C1000F (Map Panel Not Printed.) The original project was built as a lumber yard, but has not been used for that purpose for some time. Detention appears not to have been required for the site when it was built in 1974, as none is in evidence. The current area of the site is 4.48 acres. However, South Mason Street is slated for "midtown" redevelopment, and an additional 0.13 acres of additional right-of-way is being requested by the City of Fort Collins to expand S. Mason Street. The main building of the site will remain (will be remodeled), with two areas of expansion, one on the west side of the building, and one on the north. An outdoor lumber storage area on the east side of the existing building will be removed, as well as a raised concrete loading dock on the west side of the site and other concrete pad areas. The aging pavement on the site will be removed and replaced. The current drainage pattern consists of a large shallow swale within the west parking area of the site, which directs runoff south to W. Harmony Road via an existing drive entrance, and slope to the east from the east , . `ti�;i ��. .�.Il: �1 .,1. �r.ii.. illri � �li.�li,.. �. (: �'.,_ , ii� . .�ui�_I � � V i;i. �/1-.i�i� ' , • � side of the main building, towards S. Mason St. via a drive entrance located near the south end of the S. Mason Street frontage. Both streets drain to the intersection of 5. Harmony Rd, and S. Mason St. to an existing 10' Type R inlet located on the S. Mason Street side of the intersection. This inlet will be moved west approximately 7' to be in line with the proposed street widening of S. Mason St. The proposed grading will follow a similar pattern. The entrance locations will both change. The W. Harmony Road entrance will be reduced in width to accommodate a bus pullout proposed to be built immediately west of the drive (eliminating traffic hazard from buses stopping in the lane of this busy street.) The S. Mason St. entrance will be moved approximately 300 feet north to near the northeast corner of the site. The runoff which previously drained to the entrance will be re-routed to S. Mason St. with a small channel and chase section located near the southeast corner of the new proposed parking lot. A low area in the southwest corner of the site, with no apparent outlet, will be raised such that the runoff can be directed to the low point in the parking area east of the W. Harmony Road drive entrance. An existing chase section at that location will be extended north approximately ten feet, as the landscape area behind W. Harmony Road will be widened. The existing site impervious area is approximately 158,473 square feet, while the proposed impervious area is approximately 158,656 square feet, a difference of 138 square feet. The extra approximately 500 sf of drive area in the existing parcel along S. Mason St. which is not included in the total new impervious area since it is in the new right-of-way dedication, is not relevant since it the same amount as was removed from the same 0.13 acres of new right-of-way. Also, the total of approximately 640 sf is still less than the threshold 1000 sf net of new impervious area which triggers a requirement for Water Quality Capture Volume. Impervious area Total area New Site 158655 sf 4.48 ac. Old Site 158,472 sf 4.35 ac. Difference 138 sf 0.13 ac. Therefore, we believe the drainage provisions for the proposed re-development of the Fort Collins Jeep Dealership is in substantial conformance with the previously-approved stormwater treatment. The imperviousness will not increase substantially over the existing site, nor will the site outflows, and the presence of landscapir��'�j}�ing will help improve water quality. �... ♦. Sincerely �0�;� y `�, � Ny� / � ' 34200 , � -v: � :� Troy W. 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N Meters 0 15 30 60 90 A � o � � ,� � �"�P P�J�: Web Mer�tor Corner 000rcfinates: WG584 Edge tia: UTM Zaie 13N WGS&t l SI),� Natural Resources Web Soil Survey � Conservation Service National Cooperative Soil Survey • w Hydrologic Soil Grou�Larimer County Area, Colorado (Fort Collins Jeep Dealership) 483190 493210 4.9323D 4�250 486270 4�J3290 � � � � � �r� �.� _ . q` ,.�� _.�_ , �; � ,�•;�. ;�O �. a �� r�� r I'�'�' �!D � ;,� . � ' � ,� '' i y, '�'f�t��f�� r„' _ . _ ��, r t ' _• '�" '_ � ' �� eQ�� A��iQAt�'��'=�� ., ; - �� i ' I' �, . � . � � � ` ,� �� _ .. � . . 4 �i �i:05:� ' '. I .� . � � �_ 3 & � �, ■ 40° 31'31"N 1 . � � _� � S � ig � 1 — � � � l � ` I � � �� '^E�, � j ' � — � �.�. � zc� �� .�- .��,� .,� �� ;- .�� - F �,,�' �. .1- � �� ; - � .�.� ., .._ , �; --- -__ �. �Soil Map may not be v�lid at;tl�is s�c=a;l,e. , .�... .�.�.....r� " �"'`x i ' , � ' � �'— .. � . � tti' aa� 3i za• r� I ._ I �.�� I_, i� �� lr , I � ao° 31' 24" N 493170 493190 483270 4937.i� 4.93ZFA 49(i270 4fC32�J0 493310 3 S 0 3/9/2017 Page 1 of 4 0 • Hydrologic Soil Group—Larimer County Area, Colorado Hydrologic Soil Group Fort Collins Jeep Dealership Hydrologic Soil Group— Summary by Map Unit — Larimer County Area, Colorado (C0644) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 4 AltvanSatanta loams, 3 B 0.3 5.8% to 9 percent slopes 74 Nunn clay loam, 1 to 3 C 4.5 91.6% percent slopes 75 Nunn clay loam, 3 to 5 C 0.1 2.6% percent slopes I _ Totals for Area of Interest 4.9 100.0°/a Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. � l�IL� Natural Resources Web Soil Survey 3/9/2017 � Conservation Service National Cooperative Soil Survey Page 3 of 4