HomeMy WebLinkAboutSite Certifications - 05/25/1999Fr.
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Dear Mr. Barber:
THE SEAR -BROWN GROUP
FULL -SERVICE DESIGN PROFESSIONALS
209 SOUTH MELDRUM
FORT COLLINS, COLORADO 80521-2603
970-482-5922 FAX:970-482-6368
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May 13, 1999 a
Mr. Jay Barber
Utility Department
CITY OF FORT COLLINS
P.O. Box 580 / 700 Wood Street
Fort Collins, CO 80522
RE: O.D.'s Sports Crossing, Detention Pond Drainage Certification
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Our files contain a partial drainage certification forwarded to your office on September 30, 1996.
In this letter, site drainage improvements were certified; excluding the temporary detention pond as
noted under Item #5 of the letter. A copy of this letter is attached.
Though the attached letter indicates a subsequent letter would follow certifying the pond, neither
the City's files nor our files contain a copy of a second certification letter. Therefore, we are
submitting this letter certifying the "as -constructed" condition of the pond' and its associated outlet
works:
The temporary detention pond facility lies northeast of the O.D. Sports Facility. The pond was
constructed in the summer of 1996. A topographic survey was performed on April 7, 1999. Based
on this survey, the "as -constructed" volume with one -foot (l') of freeboard has been determined to
exceed the minimum design volume of 0.70 ac-ft. In addition, the outlet pipe is 15" HDPE and
contains an orifice plate at its upstream end with a 5-3/4 inch diameter opening. The pipe and
orifice plate sizes are per the requirements of the final Drainage Report and construction drawings.
Therefore, the pond and its associated outlet works have been constructed in conformance with the
design requirements. The results of this survey are summarized in the following table:
NEW YORK • PENNSYLVANIA
COLORADO•UTAH•WYOMING
STANDARDS IN EXCELLENCE
EQUAL OPPORTUNITY EMPLOYER
Parameter
Units
Design
"As-Built"-
O.D. Sports Crossing
Invert of Outfall Orifice
ft-MSL
4955.00
4954.60
100 Year WSEL (design vs. as -built w/ 1'
freeboard)
ft MSL
4959.91
4960.16
Detention (required vs. provided @ 1'
freeboard)
ac-ft
0.70
0.73
Freeboard
feet
1.001
1.00
Release Rate "1
cfs
1.881
2.04
(')Release Rate = CdA (2gh)" 2
=(0.60)x(3.14x((5.75/12)/2)2)x[(2x(32.2)x(4960.16-4954.60))]12
=(0.60)x(3.14x((0.24)2)x[(2x(32.2)x(5.56)]12
= (0.60)x(o.18)x(18.92)
= 2.04 cfs
This certification is signed and stamped and by signing this letter I attest that to the best of my
knowledge the as -built conditions of the drainage facilities constructed to date are as described
above and on the redlined construction drawings enclosed. Failure to properly disclose all known
information could result in the rejection of this certification and prevent the release of any
Stormwater Utility holds on Building Permits and/or Certificates of Occupancy.
Should you have any questions regarding this certification, please feel free to call.
cc: Joe and Rachael Olbrys
648-001.a
file:I ;\jobs\684-00l%docs\pond-certletter.doc
LD
/, 47
THE SEAR -BROWN GROUP
FULL -SERVICE DESIGN PROFESSIONALS
209 SOUTH MELDRUM
FORT COLLINS, COLORADO 80521-2603
970-482-5922 FAX:970-482-6368
May 13, 1999
Mr. Jay Barber
Utility Department
CITY OF FORT COLLINS
P.O. Box 580 / 700 Wood Street
Fort Collins, CO 80522
RE: O.D.'s Sports Crossing, Detention Pond Drainage Certification
Dear Mr. Barber:
Our files contain a partial drainage certification forwarded to your office on September 30, 1996.
In this letter, site drainage improvements were certified; excluding the temporary detention pond as
noted under Item #5 of the letter. A copy of this letter is attached.
Though the attached letter indicates a subsequent letter would follow certifying the pond, neither
the City's files nor our files contain a copy of a second certification letter. Therefore, we are
submitting this letter certifying the "as -constructed" condition of the pond and its associated outlet
works.
The temporary detention pond facility lies northeast of the O.D. Sports Facility. The pond was
constructed in the summer of 1996. A topographic survey was performed on April 7, 1999. Based
on this survey, the "as -constructed" volume with one -foot (l') of freeboard has been determined to
exceed the minimum design volume of 0.70 ac-ft. In addition, the outlet pipe is 15" HDPE and
contains an orifice plate at its upstream end with a 5-3/4 inch diameter opening. The pipe and
orifice plate sizes are per the requirements of the final Drainage Report and construction drawings.
Therefore, the pond and its associated outlet works have been constructed in conformance with the
design requirements. The results of this survey are summarized in the following table:
NEW YORK•PENNSYLVANIA
COLORADO•UTAH•WYOMING
STANDARDS IN EXCELLENCE
EQUAL OPPORTUNITY EMPLOYER
Parameter
Units
Design
"As -Built"
O.D. Sports Crossing
Invert of Outfall Orifice
ft-MSL
4955.00
4954.60
100 Year WSEL (design vs. as -built w/ 1'
freeboard)
ft MSL
4959.91
4960.16
Detention (required vs. provided @ 1'
freeboard)
ac-ft
0.70
0.73
Freeboard
feet
1.00
1.00
Release Rate "1
cfs
1.881
2.04
V*
1'1Release Rate = CdA (2gh)112
=(0.60)x(3.14x((5.75/12)/2)Z)x[(2x(32.2)x(4960.16-4954.60))]12
=(0.60)x(3.14x((0.24)Z)x[(2x(32.2)x(5.56)]"Z
= (0.60)x(0.18)x(18.92)
= 2.04 cfs
This certification is signed and stamped and by signing this letter I attest that to the best of my
knowledge the as -built conditions of the drainage facilities constructed to date are as described
above and on the redlined construction drawings enclosed. Failure to properly disclose all known
information could result in the rejection of this certification and prevent the release of any
Stormwater Utility holds on Building Permits and/or Certificates of Occupancy.
Should you have any questions regarding this certification, please feel free to call.
cc: . Joe and Rachael Olbrys
648-001.a
file:I ;\jobs\684-00I\docs\pond-certletter.doc
L�