HomeMy WebLinkAboutREGISTRY RIDGE, 5TH FILING - PDP - 32-95I - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTIn essence, the proposed Design Point will remain in the same location as the historic
Design Point, ultimately being routed into Pond 603. The proposed runoff coefficients
are reduced from the historical design and proper erosion control and water quality
devices shall be installed and maintained.
Please feel free to contact me with any questions you may have regarding this letter.
Respectfully,
Cody N. Snowdon, EI
ADDRESS: PHONE:970.221.4158
NORTHERN 200 S. College Ave. Suite 100 wEBSITE:
ENGINEERING Fort Collins, C080524 FAX:970.221.4159 wmnorthernengineeringtom
VFebruary 27, 2007
Basil Harridan
City of Fort Collins
215 North Mason
Fort Collins, CO 80549
RE: Registry Ridge Fifth Filing
Basil,
. This letter is in regards to Registry Ridge Fifth Filing development in Fort Collins,
specifically, the proposed drainage patterns of the project.
The site is a replat of the Tract C, Tract H and Tract F of the Corrected Plat of the Final
Plat of Registry Ridge P.U.D., First Filing. The overall area being conveyed is 16.18
acres composed of historical drainage Basins 403G, 403H, 403I and 402D of Registry
Ridge First Filing. The storm water is conveyed by a combination of overland, Swale and
gutter flow from the northwest corner of the site to historical Design Point 22 with a
further destination of Pond 603. This site was originally designed and approved in June
of 1999 as a combined Regional Park and School area. The composite runoff actual
composite runoff coefficient for the proposed area is 0.38 for the 2-year storm and 0.48
for the 100-year storm, thus the proposed site will have less imperviousness then
originally anticipated. For specific calculations, see the attached spreadsheet.
7.069% of historic Basin 402D and 31.290% of historic Basin 403G will enter the site by
form of overland and curb and gutter flow. Hence, slightly decreasing the amount of
capacity needed for the inlets at Design Point 10 and 18.
Proposed Basin A will convey stormwater by Swale to Design Point A (historical Design
Point 22). Proposed Basins B and C will convey runoff by a combination of overland
and gutter flow into two combination inlets and further to Design Point A. Proposed
Basin D shall create overland runoff to the southern Swale as previously designed.
Basins A-C shall be routed through a water quality retention pond at the southeast corner
of the site with a storage capacity of 0.154 acre-feet before entering the existing
stormwater system. An emergency spillway is graded at the south end of the retention
pond that spills into the existing Swale.
There will be multiple erosion control devices implemented within the site project. Sand
bag check dams will be used in three places along the existing Swale to decrease the
amount of sediment accumulation at Design Point A. Straw bale sediment traps shall be
installed at both combination inlets. In addition, silt fencing shall be installed and
maintained along the perimeter of the project site.