HomeMy WebLinkAboutFREY STREET COTTAGES SUBDIVISION - PDP - 17-06 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTwide driveway to catch the flows from Frey Avenue from both the North and South. The
outlet from the pipe is into the ditch at the historic high water line mark.
The detention pond will also include extended detention for the 40-hour drain time. A
water quality structure is designed for the outlet from the pond to the Larimer canal No.
2. The outlet elevation is set at the Canal's high water line.
A variance is requested for the minimum 12-inch freeboard in the pond. We have a 0.44-
inch freeboard. The variance is needed:
1. Due to an infill project and the area is small.
2. The pond is long and narrow and will not have wave action.
3. The pond filled has 1.3 times the total required volume.
EROSION CONTROL AND BEST MANAGEMENT PRACTICES
This site is in the City's moderate rainfall erodibility and moderate wind erodibility zone
The new storm drain system will be protected during construction with waddles around
the inlets on both sides of Frey Avenue. 18-inch diameter rip rap will be required at the
storm drain outlet into Larimer County Canal.
A 40-hour extended detention pond is added to the required pond volume and its release
rate is controlled as designed in a water quality outlet structure. After the structure is
built there will be a straw bale dike installed around the structure. The outlet into the
ditch shall have 18-inch diameter rip rap.
The bottom of the pond will be dug out 12-inches deeper than designed and used as a
sediment pond during construction. Also a silt fence will be constructed along the North,
East and South sides of the project during construction.
Required city escrow amount is $8,265.00.
Sincerely,
`� Franklin D.
STEWART&ASSOCIATES
Consulting Engineers arxi Surveyors
June 5, 2006
Basil Hamdam
Storm Water Utility
City of Fort Collins
PO Box 580
Fort Collins, CO 80522
Dear Basil,
Frey Avenue Cottages is a replat of Lots 9 and 10 and the North 18 feet of Lot 8, Block 2,
Frey Subdivision situate in the Southwest 1/4 of Section 10, Township 7 North, Range 69
West of the 6th P.M., Fort Collins, Larimer County, Colorado. The site gross area to the
centerlines of Frey Avenue and Laporte Avenue is 1.2 acres.
EXISTING SITE
There is an existing house, garage, recycled asphalt parking area and gravel driveways.
The yards have not been maintained and are now grass, weeds and dirt. The existing site
slopes West to East at 1% more or less and flows into the Larimer County Canal No. 2.
The site is bounded by Laporte Avenue on the North which is curb, gutter and pavement;
Larimer County Canal No. 2 on the East; developed single family residence on the South;
and North Frey Avenue on the West which is presently gravel.
This property historically received runoff from the West that flows across the South end
of our site into Larimer County Canal No. 2.
There are several low spots that hold water during storms upstream and on our site. See
the offsite exhibit map for sub -basin to this site. It begins at the New Mercer Canal as the
West boundary. This offsite area is 10.4 acres.
DEVELOPED SITE
The developer is proposing five single family homes with a common driveway for all
five. The driveway is proposed to be 2-feet of concrete, 5-feet of grass, 5-feet of concrete
in the middle, 5-feet of grass and then 2-feet of concrete. A detention pond is proposed
along with the wild life corridor. The ponds release rate is the two year historic runoff
rate. A storm sewer will be constructed along our South property line to handle the
offsite flows to the existing alley on the West side of Frey Avenue. A double wide area
inlet is proposed. Also an area inlet is proposed on the East side of Frey in our 20-foot
James H. Stewart and Associates, Inc.
103 S. Meldrum Street • P.O. Box 429 • Ft. Collins, CO 80522
970/482-9331 • Fax 970/482-9382
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DRAINAGE, EROSION CONTROL AND WATER QUALITY REPORT
FREY AVENUE COTTAGES
SITUATE IN
CITY OF FORT COLLINS CANAL
IMPORTATION BASIN MASTER PLAN AND OLD TOWN BASIN
PREPARED
FOR
JOHN SHAW
r
JUNE 59 2006
0
PREPARED BY
STEWART & ASSOCIATES, INC.
P.O. BOX 429
103 SOUTH MELDRUM STREET
FORT COLLINS, COLORADO 80522
TEL: 970.482.9331
FAX: 970.482.9382