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HomeMy WebLinkAboutSite Certifications - 12/15/2005AIRE5 ASSOCIATES December 12, 2005 Mr. Jay Barberr- City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 Re: Drainage Certification for the Coloradoan Newspaper building, 1300 Riverside Avenue Dear Jay, We recently surveyed the lot grading improvements for a new commercial office building located along Riverside Avenue north of Prospect Road and east of Lemay Avenue in Fort Collins. Spot elevations and drainage patterns were checked at pertinent locations to verify whether the grading sufficiently drains stormwater runoff. The enclosed drawing shows the as -built elevations. There is positive drainage away from the building on all sides. The finished floor elevation is at 4951.93 feet, within 0.07 feet of the design elevation. Well over 100 spot elevations were surveyed on the ground adjacent to the office building, the parking lot, and collection swale. In general all of the precipitation that falls on this lot will drain to the back of the lot. The parking lot west of the building contains an inlet that collects water from the front of the lot and carries it to a swale behind the building. The back portion of this lot drains toward the north and out a curb cut into the back swale. The front parking lot drains into a pan that slopes off to the southeast. The east parking lot drains away from the building to the east as well. A curb runs parallel with the east property line and causes the runoff to drain to the back corner (northeast), through a curb cut and into the back swale. There is a patio area on the southwest side of the building, which drains into the inlet that will collect runoff pipe the water underneath the building north to the back swale. The swale along the back of the lot drains parallel to the building toward the northeast corner. A water quality outlet structure at the northeast corner was constructed with a well screen and six 3/8-inch orifice holes. Site runoff would discharge through the water quality outlet or overtop a 24-inch high retaining wall toward the northeast onto the railroad right-of-way, consistent with the design plans. The inlet and storm sewer pipe in the west parking lot was shifted to the east to avoid curb islands within the parking lot and a light pole base. Also, instead of paving the parking lot with asphalt, concrete was used throughout. A positive slope is maintained at all locations on the building development site. It is my recommendation that the Certificate of Occupancy for this property be released since the lot has been graded to protect the existing structure. If you have any questions, please call. Sincerely, Ayres ssociates Inc Chris er L. Dohe P.E. Proj t Manager - Water Resources CLD:sp Enclosure Engi neers/Scientists/Su rveyors M65 JFK Parkway, Building 2, Suite 200, FW Collins, CO 80525-3152 (970) 223-5556, FAX (970) 223-5578 www.AyresAssociates.corn BARBI2L.DOC 32-0888.00 LEGEND: GRAPHIC SCALE: Or ® 9,E,w..c ow — .wasso corm. 20- Q" -w,t aw ..r �.,,r..o, •- -•�..,wo� ..r,.-ter 1 :,..w- .o n. NO , WTF� , 0 . m GRAPHIC SCALE: GVl Unun NCT F uE•N ttME0. OF COLOM 1-800-922-1987 w�303 l32-1(1j= - p x I I Eat oaw� w 1414I s' GRAPHIC SCALE: I ro. m. a GRAPHIC SCALE: LEGEND: -yyjq -cmnc nw.c-sro. niwwv. -�,W -mr o cue-mm aevu. .�iPAl -ns�m wa�sw. nuawm. -y�� -mwnm nwv< mm on.0 -EY-id, -oosrw �« « mnrc. -fir. -rzuww. rwa.m w.�s-noNrE ENTRY GRADING DETAIL NORTHEAST CORNER GRADING DETAIL GRAPHIC SCALE: q :h a i City of FDA Collins, Colorado UTILITY PLAN APPROVAL •tn.��_ co ED BY EDP ED 9 THN ENOINM RING n. SKRV10E.s. INC. ml RETAINING WALL PROFILE GRAPHIC SCALE: ';� Qi LEGEND: a NORTHERN T— n. ENOINEENINO EENYN:Es.