HomeMy WebLinkAboutSite Certifications - 12/29/2005STORMWATER
RECEIVED
December 29, 2005
Mr. Jay Barber
City of Fort Collins
Stormwater Utility
700 Wood Street
JAN o s zoos
Fort Collins, Colorado 80521
Re: Drainage Certification for Timberline Terrace Office Building (2038 Vermont Drive)
Dear Jay,
AM ES
ASSOCIATES
)_P4
We recently surveyed grading and drainage improvements associated with the construction of a new office
building, parking lot and related landscape. The subdivision is located on the north side of Vermont Drive,
west of Timberline Road in southeast Fort Collins. Spot elevations and as -built contours were checked at
pertinent locations and compared to the grading plan to verify whether the grading met the intent of the
approved grading and drainage plan. The enclosed drawing shows both the grading plan and as -built spot
elevations.
In general, the lot and building construction meet the requirements of the grading and drainage plan and
there is positive drainage away from the building on all sides. The intended drainage patterns are met by
the grading on this lot, with slopes set for drainage to flow radially outward from the building. The finished
floor elevation of 4942.0 meets the design elevation. The minimum slope away from the building is in
excess of 3 percent (0.63 feet over 20 feet).
In order to promote positive drainage through the project site, two Feld design changes were required:
On the south side of the building, the contractor and owner constructed a 2-foot wide concrete pan
rather than a grass -lined Swale. The upstream invert was lowered 0.4 feet from design to promote
drainage away from the building, and the slope was reduced from approximately 1 percent to 0.66
percent.
In the north parking lot, several changes were made to allow positive drainage to the detention pond,
constructed to the northeast in conjunction with Home State Bank. A new 10-foot wide driveway cross
pan was constructed at the west entrance to the detention pond to lower the flowline elevation several
inches, because the existing elevation would not have allowed positive drainage. A 2-foot wide
concrete pan was constructed to the west curb line; the as -built elevation on the west end of the pan is
approximately 0.5 feet lower than design to promote positive drainage from the adjacent property. The
contractor further intends to cut the curb at this location to allow positive drainage from adjacent
landscape areas. The final condition will allow for positive drainage, where the initial design would not
have. The 2-foot wide concrete pan was also extended along the east side of the western driveway to
eliminate nuisance flows over asphalt pavement.
It is my recommendation that the Certificate of Occupancy be released since the Contractor constructed
the building and graded the lot to meet or improve upon the design drainage patterns. If you have any
questions, please call.
Sincerely,
Ayres AP
its Inc
Christooherty,
Project — Water Resources
CLD/sp
Engineers/Sdentists/Surveyors
3665 JFK Parkway, Building 2, Suite 200, Fort Collins, CO 80525-3152
(970) 223-5556, FAX (970) 223-5578
www.AyresAssociates.com
BARBI2LT.DOC
32-981.00
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