HomeMy WebLinkAboutSite Certifications - 04/17/1996 (2)STORMWATER
RECEIVED
APR 17 1996
A Engineering, Ltd. LETTER OF TRANSMITTAL
4812 S. College Ave. - Date: ' 17-Apr-96., '
Fort Collins, CO 80525 Joti Name: COVENTRY SUBDIVISION FILING NO. 1
Tel (970)282-4335 RE: STORMWATER CERTIFICATION Fax (970) 282.4340 Job No: 9007.03
TO: CITY OF FORT COLLINS STORMWATER UTILITY
Attention:
We are sending you:
BASIL HAMPDON
]Attached
Shop drawings
Originals
Other (Vellums)
THESE ARE TRANSMITTED as checked below:
❑ For approval
K]Foryouruse
jAs requested
For review and comment
FOR BIDS DUE
Remarks
PLEASE CALL IF YOU HAVE ANY QUESTIONS.
COPY tO: FILE
Signed
Received
❑ under separate cover via the following items:
]Prints nMylam
X Documents
❑ Computer Disks
Approved as submitted Resubmit
Approved as noted Submit
Returned for corrections FIRetum
❑ Delivery
❑ PRINTS RETURNED AFTER LOAN TO US
F. SCOTT WATERMAN
copies for approval
copies for distribution
corrected prints
JREngineering, Ltd.
4812 South College Avenue
Fort Collins, Colorado 80525
(303) 282-4335 • FAX (303) 282-4340
April 17, 1996
Mr. Basil Hampdon
City of Fort Collins Stormwater Utility
235 Mathews
P.O. Box 580
Fort Collins, CO 80522-0580
Re: Coventry Subdivision Filing No. 1 Stormwater Asbuilts
Dear Basil:
4935 North 30th Street
Colorado Springs, Colorado 80919
(719) 593-2593 • FAX (719) 528-6613
6110 Greenwood Plaza Blvd.
Englewood, Colorado 80111
(303) 740-9393 • FAX (303) 721-9019
Please find attached the stormwater asbuilt "package" for Coventry Subdivision Filing No. 1.
Included in this package are redlined stormwater utility plans, as surveyed after construction, and
the required drainage certification form with supporting documentation. (The field work was
completed by JR Engineering, Ltd. on January 17, 1996.)
Several of the items requested on the drainage certification form are vague and we have provided
additional information or reasoning supporting our answers. The following comments make
reference to items I through VI as designated on the drainage certification form:
I) A) Attached is supporting documentation of the required detention volume, in
accordance with the approved final drainage study, and the actual field surveyed
detention volume.
B) The pipe outlet orifice has been completed as of this date.
II) A) The compaction of the berm and the structural integrity of the pond is outside of
our scope of involvement in this project.
B) The City of Fort Collins Parks and Recreation Department is having alterations
constructed to this pond which may affect the structural integrity of the berm.
(They are increasing the irrigation storage.)
III) These items are outside our scope of involvement in this project. We believe the
appropriate field inspector for the City of Fort Collins may have better information on
these items.
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IV) Items covered in this section are related to conditions after final build out of the
subdivision. These items can not be addressed at this time as the houses have not been
built in the areas where the top of foundation elevations are critical in relation to nearby
100 year water surface elevation.
V) Insuring that temporary erosion control measures are in place is the responsibility of the
developer.
VI) Site cleanup is outside of JR Engineering, Ltd.'s scope of involvement in this project.
If you have any questions or comments regarding the submittal of these items, please contact me
at 282-4335.
Sincerely,
JR Eneieeerine/Ltd.
--
M. Kellogg, Jr., P.E.
RMK/fsw
Attachments
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DRAINAGE CERTIFICATION FORM
Please fill out all applicable items in this certification form
for single family, multi -family and commercial properties.
Write "OK" for items checked or actual number checked in field.
Use "N/A" for items that are not applicable to the property that
is being certified.
A. Drainage facilities certification
1. Pond Certification
-volume verification v�C'
a. topographic records and volume
b. cross -sections and spot elevations O K.
-positive fall to pan iJ1�
-side slopes CY,
-invert elevation Or._
-spillway elevation 0 k-
'placement and size of riprap 0<<
-side slopes O1'_
-grading
-orifice plate installation and size U1L
compaction of berm NA O
-structural integrity of pond IJP
2. Swales
-location (are they within easement) _v--
dimensions and cross-section verification Dom.
-longitudinal slopes and side slopes
-spot elevations C)IC-
-permanent erosion control measures Q�
(drop structures, riprap, etc....)
-tie-in to pipes, pans, curbs, etc....
-weir size (elevations, size, opening, etc...) ►J6
-available freeboard
-landscaping infringement on swales �Jt'-
3. Pipes
-size and type �K..
-slopes (as -built and comparison to minimum
.0.4% slope) Q
-pipe capacity calculations if slopes are
,significantly altered N
-invert elevations OK
-installation and backfill material O A
-cover }�
encasement and clearance from other utility �(
lines close by MA
joints _�
4. Concrete Pan Channels
-size p1L
-slope ol_
-super elevation N fi
-cross-section O1L
-thickness ^)A-
-elevations 0k
S. Inlets
-size and type —V
-size of opening (or .name of standard used) OL_
-grate elevation 0y,
-invert elevation OIL
-box size 0Y_
6. Cross pans
-size O_
-.type OY_
-grade p�
-elevation
-cross-sectional depth CK-
-tie-in to curb and gutter pIL
7. Culverts
-size tiA
-type N A
-invert elevation IAA
-headwalls &)A
8. Underdrains
-size NA
-type
-cover
-backf ill N A
-geotextiles jit
-cleanouts "Jk
9. Curb cuts
-size
-tie in to swale, pipe, etc.... IJ R
:f
B. Certification of Grade Elevations Adjacent to
Drainage Facilities:
-minimum opening elevations OA
-top of foundation elevations N R
-comparison to 100 year WSEL's JJ�
(Freeboard requirements and floodplain issues)
C. Certification of Erosion Control Measures:
1. Permanent Measures:
-Permanent vegetation (6" bare spots and weeds
under control) OPT
riprap
-riprap bedding DK-
-drop sections i�1R
-sediment basins/water quality ponds N A
-netting mats/blankets Nfa
-mulching
0
2. Temporary Measures.
-mulching riIk
-inlet filter installation
-check bale dams UK-
-seeding and temporary vegetation J\J6
-silt fence AIL
D. Site Cleanup After Construction
-construction clean up
-smoothing of ruts
-reseeding_
E. Statement of Compliance
This certification is signed and stamped and by signing this
form the engineer(s) attests that to the best of his knowledge
the as -built conditions of the drainage facilities are as
described in the above form and in the redlined plans 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.
F. Signature and Stamp by a Colorado Registered Professional
Engineer.
HYDROGRAPH DISCHARGE TABLE Cont'd
TIME
INFLOW (i)
INFLOW (j)
2S/dt-O (i)
2S/dt+O (j)
OUTFLOW
hrs
cfs
cfs
cfs
cfs
cfs
11.63
0.00
0.00
810.14
812.75
1.31
11.65
0.00
0.00
807.54
810.14
1.30
11.67
0.00
0.00
804.93
807.54
1.30
11.68
0.00
0.00
802.33
804.93
1.30
11.70
0.00
0.00
799.74
802.33
1.30
11.72
0.00
0.00
797.15
799.74
1.30
11.73
0.00
0.00
794.56
797.15
1.29
11.75
0.00
0.00
791.98
794.56
1.29
11.77
0.00
0.00
789.40
791.98
1.29
11.78
0.00
0.00
786.83
789.40
1.29
11.80
0.00
0.00
784.26
786.83
1.28
11.82
0.00
0.00
781.70
784.26
1.28
11.83
0.00
0.00
779.13
781.70
1.28
11.85
0.00
0.00
776.58
779.13
1.28
11.87
0.00
0.00
774.03
776.58
1.28
11.88
0.00
0.00
771.48
774.03
1.27
11.90
0.00
0.00
768.93
771.48
1.27
11.92
0.00
0.00
766.39
768.93
1.27
11.93
0.00
0.00
763.86
766.39
1.27
11.95
0.00
0.00
761.33
763.86
1.27
11.97
0.00
0.00
758.80
761.33
1.26
11.98
0.00
0.00
756.28
758.80
1.26
12.00
0.00
0.00
753.76
756.28
1.26
Maximum
outflow (cfs)
= 2.
';;
_ PEqkAXRP-O
vow,nE
Maximum
storage (cu ft)
= 100134
:;
�. FiZonn p�gSw�E
Maximum
elevation (ft)
_ .48.33
Q
Q£Po T
D
D-21
COVENTRY SUBDIVISION DETENTION POND
Contour
Area
Volume
40.6
0.00
0.00
41.0
2549.22
339.90
42.0
13661.05
7370.51
43.0
16273.84
14948.40
44.0
18663.70
17455.13
44.5
19929.59
9646.59 (Outlet pipe orifice elev.)
45.0
21195.48
10279.64
46.0
23894.53
22531.53
47.0
26753.92
25310.76
48.0
29785.61
28256.21
49.0
33125.19
31440.62
49.4
34648.64
13553.62 (Weir elevation.)
TOTAL VOLUME
181132.9 CF = 4.16 AC -FT
contours (44.5-49.4) DET. VOLUME= 131372.4 CF = 3.02 AC -FT
contours (40.6-44.5) IRR. VOLUME= 49760.5 CF = 1.14 AC -FT
Note: These volumes are based on existing field conditions on January 17, 1996 when
an as -built field survey was performed. Pipe outlet orifice was not completed but
had been staked.
FIELD.XLS