HomeMy WebLinkAboutSite Certifications - 05/17/2013INTERWBST - CONSU LT 7 N G GROUP
May 7, 2013
Mr. Jay Barber
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 80522
Re:VIizawner e�tonment — Storm Drainage Certification
Dear Jay,
Please accept this letter and the attached drawings as the Drainage Certification for the Elizabeth
& City Park Corner Redevelopment project located at 1401 W. Elizabeth Street. The attached
survey information was provided by Washburn Land Surveying on May 3, 2013. Based on this
survey data and a site visit conducted May 7, 2013, the project is in substantial conformance with
the approved plans and drainage letter.
The proposed building finished floor was constructed per the approved design drawings. The
areas around the proposed building appear to drain per plan. All runoff from the site follows the
proposed drainage paths.
The inlet and underdrain system for the pervious landscape detention system (rain garden) was
installed per plan per the contractor, Sampson Construction Company, Inc. The contractor also
confirmed that the rain garden media was per the approved design drawings.
The rain garden was not constructed per plan. The original proposed volume was 420 cubic feet.
The as -built volume is approximately 225 cubic feet (15'xl5' and 54% of the design volume).
During construction, utilities were installed above the underdrains on the south end of the facility
and it was not possible to excavate over these power and communications lines during final
grading. This reduced the square footage of the facility (see photo 1 below). After final grading,
the project owner cited liability concerns with the proposed drops off of the back of curb and had
the contractor fill the rain garden with large cobble (see photo 2 below).
�l ,
Mr. Jay Barber
May 7, 2013
Photo 1.
Photo
2.
V
Mr. Jay Barber
May 7, 2013
Page 3 of 3
It is our opinion that the rain garden, constructed as is, will still function adequately and will
achieve water quality treatment for the site. Due to the nature of the site (infill).and the fact that
the redevelopment has improved upon the existing conditions"by reducing the overall impervious
area, the constructed project has a positive impact on the overall stormwater management
system.
If you have any questions or.need additional information please feel free to call at any time (970)
460-8471. .
Sincerely,
i
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