HomeMy WebLinkAboutSite Certifications - 07/28/2004Odom" & 041 "Oda 4e lox,
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Pdmer (970) 461-0550
57axr (970) 461-0551
July 25, 2006
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80526
RE: Drainage Certification for Lot 2 of Peterson Place Subdivision, City of Fort Collins, County.of
Larimer, State of Colorado, AKA #11if South Peterson Street.
Dear Sirs:
On July 24, 2006, we observed the site located on Lot 2 of Peterson Place Subdivision. The site had
been final graded. In addition to our observation, Intermill Land Surveying obtained spot elevations at
numerous spots throughout the site. Please refer to the attached elevation sheet.
The pad of the building, sidewalks, parking lot, sidewalk culverts, swales, and utilities were already
installed. The building is constructed and the landscaping is installed.
Based on our observation and the attached survey information, the site generally appeared to drain
away from the building. The small areas north and east of the building drains northerly or easterly
toward a grass swale that drains into a concrete curb and gutter located adjacent to the southern
boundary. The area south of the building drains southerly away from the building and into the
concrete curb and gutter. The concrete curb and gutter drains easterly into the existing gutter of South
Peterson Street. The area west of the building drains west towards the detention pond. Please refer to
the pictures attached.
The finished floor elevation given by Intermill Land Surveying is 4987.00 feet, the design elevation is
4985.86 feet. However, from our visual observations, it appears that the datum for the as -built
information is different than the datum for the design drawings.
The grading around the building generally conforms to the Final Grading Plan — Sheets 5 — Peterson
Place prepared by Loonan & Associates Inc., as revised, dated 1/7/2006. However, the detention pond
located in the parking lot located west of the building was not graded per the revised grading plan.
From the survey information provided by Intermill Surveying, the bottom of the pond/parking lot has a
low point that will not drain. Also, the high points between the alley and the parking lot, as well as the
high point located between the parking lot and the sidewalk, are not high enough to prevent stormwater
from spilling. The required volume of detention ponding is 385 cubic feet. The Detention Pond as
�s2 1
k 1�6
constructed holds only 202 cubic feet. However, if these high points were raised 0.13 feet, the
resulting volume will be 384 cubic feet.
The 1 'h inch diameter outlet pipe was installed and there is a grass filter strip between the,outlet pipe
and the concrete curb and gutter.
Our recommendations are based on our observation on the date noted above. The geotechnical report
was not provided to use for this site, therefore we cannot determine if the site has been graded
according to the geotechnical report.
If you -have any questions, please contact me at the above address or phone number.
Sincerely����"�p0 RE
James Rpan, P.E
��s�ONAI,E��`�.
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in
Peterson Place
Detention Pond Volumes - AS-BUILTS
,
Delta Volume=(D/3)(A1+A2+SQRT(AIA2))
DELTA
if if
ELEV AREA
VOLUME
VOLUME
FT FT'
FT'
FT'
84.03 0
0
0
84.1 501
12
12
84.2 976
73
84
84.3 1398
118
202
84.43 1400
182
384 If conc is replace at edges
WQ VOLUME TOTAL
Required Volume = 0 385 385 FT'
W.S. Elevation = Elev60 - Elev59 (V0IRegwi ed-Vo159)+Elev59
V0160 - V0159
= 84.43 FT
100-year Depth (D) = 0.33 FT
Top of Berm = 84.43 FT
Freeboard = 0.00 FT
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