HomeMy WebLinkAboutFORT COLLINS SENIOR CENTER EXPANSION - Filed GC-GENERAL CORRESPONDENCE - 2016-06-01IN �� ��
JVA, Incorporated
25 Town Square
Old
'�
Suite 200
Fort Collins, CO 80524
Ph: 970.225.9099
August 5, 2013
Fax: 970.225.6923
Toll Free: 877.444.1951
Mr. Peter Barns
Web site:
City of Fort Collins — Zoning
www.jvajva.com
281 N. College Ave.
E-mail:
Fort Collins, CO 80524
info@ivajva.com
RE: Fort Collins Senior Center Expansion - Drainage Letter
JVA Job No. 2104c
Dear Mr. Barns:
This letter is prepared to summarize the drainage concept, solutions and changes in impervious area
associated with the site improvements for the Senior Center Expansion located at 1200 Raintree
Drive in the City of Fort Collins. JVA has met with Basil and Glen with the city to review the
drainage concepts discussed below and in general are in agreement. JVA is currently preparing a
detailed drainage report but due to the project schedule the report has not been finalize at this time.
Once the drainage report is finalized, a copy will be submitted for review.
Existing Drainaae Patterns
The Senior Center currently conveys stormwater to the northwest through below grade storm lines
draining to an existing regional stormwater detention pond, northwest of the site. There are two
existing on -site parking lot detention areas at the northeast and west side of the building.
Additionally there is an existing stormwater detention pond at the northwest corner of the building.
The onsite detention systems are controlled by an orifice plate, limiting the flow to the regional
detention and allowing for onsite detention. To the west of the Senior Center there is currently an
open field and gravel parking area that sheet flows to the north and conveying stormwater to the
New Mercer Canal.
Proposed Drainage Patterns
The proposed Senior Center building expansions will slightly increase the impervious area around
the building. The building expansion at the northeast corner will have an impact to the existing
parking lot detention. The parking lot detention to the west of the building will also be impacted due
to the proposed parking lot. The additional stormwater runoff and impacts to the onsite detention
ponds will be offset by adding additional detention to the regional detention pond to the north of the
site. The regional detention pond will also be modified to provide for water quality which
previously was not designed for.
The proposed parking lot to the west will convey stormwater to a proposed stormwater detention
pond that will also treat for water quality. The detention pond outlet will convey water under the
New Mercer Canal and connect to the existing 18" storm pipe which eventually outfalls to Spring
Creek. Options were discused with the New Mercer Canal representative to drain the proposed
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Fort Collins Senior Center Expansion
August 5, 2013
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parking lot to the canal but was concluded that no piped flows to the canal are allowed. The pond
will be sized to limit the release rate to the 2 year historic rainfall event. A preliminary model of the
existing storm system has been performed and appears there is capacity to convey the additional
flow from the proposed detention pond to Spring Creek.
To meet the low impact development (LID) requirements, approximately 25% of the new parking lot
area will be permeable pavers with an underdrain system. The existing regional detention pond will
be modified to incorporate water quality enhancement to address LID requirements for the existing
site.
Erosion and Sediment Control
During construction there will be temporary erosion and sediment control practices used to limit soil
erosion. These temporary erosion control devices include curb rock socks, inlet protecting,
stabilized construction entrance and silt fence.
Please feel free to contact myself or Dondi Harner to discuss any questions you may have.
Sincerely,
JVA, INCORPORATED
By: 1
J son Clayeso.E.
roject Manger
CC: Neenan
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