HomeMy WebLinkAboutDrainage Reports - 09/23/1994Fier
orf
PROPERTY OF
COLLINS uTuxrM
DRAINAGE AND
CONTROL STUDY
FOR
E BUSINESS PARK
ONE, PHASE 2
LLINS, COLORADO
--/ 2'lo ';�/
FINAL DRAINAGE AND
EROSION CONTROL STUDY
FOR
OAKRIDGE BUSINESS PARK
BLOCK ONE, PHASE 2
FORT COLLINS, COLORADO
September 2, 1994
Prepared for:
' Vaught*Frye Architects
1119 Stoney Hill Drive
Fort Collins , Colo 80525
'
Prepared by:
RED, Inc. Engineering Consultants
'
209 South Meldrum
Fort Collins, Colorado 80521
(303) 482-5922
'
RBD Job No. 183-030
1
1
1
1
1
1
1
1
1
1
1
i
1
1
1
1
1
INC.
Engineering Consultants
209 S. Meldrum
Fort Collins, Colorado 80521
303/482-5922
FAX:303/482-6368
September 2, 1994
Mr. Glen Schluter
City of Fort Collins
Utility Services Stormwater
235. Mathews
Fort Collins, Colorado 80522
RE: Final Drainage and Erosion Control Study
for Oakridge Business Park, Block One, Phase 2
Dear Glen:
We are pleased to submit to you, for your review and approval, this Final Drainage and
Erosion Control Study for Oakridge Business Park, Block One, Phase 2. All
computations within this report have been completed in compliance with the City of
Fort Collins Storm Drainage Design Criteria and all review comments by Storm
Drainage staff have been addressed.
We appreciate your time and consideration in reviewing this submittal. Please call if
you have any questions.
Respectfully,
RBD Inc. Engineering Consultants �►p�''OB
Steven C. Birdsall, P.E.
Project,Engin
Stan A. Myers, P.E.
Project Manager
Denver303/458-5526
TABLE OF CONTENTS
DESCRIPTION
PAGE
I. GENERAL LOCATION AND DESCRIPTION
1
A. LOCATION
1
B. DESCRIPTION OF PROPERTY
1
II. DRAINAGE BASINS
1
A. MAJOR BASIN DESCRIPTION
1
III. DRAINAGE DESIGN CRITERIA
1
A. REGULATIONS
1
B. DEVELOPMENT CRITERIA REFERENCE
2
AND CONSTRAINTS
C. HYDROLOGICAL CRITERIA
2
D. HYDRAULIC CRITERIA
2
E. VARIANCES FROM CRITERIA
2
IV. DRAINAGE FACILITY DESIGN
3
A. GENERAL CONCEPT
3
V. STORM WATER QUALITY
4
A. GENERAL CONCEPT
4
VI. EROSION CONTROL
4
A. GENERAL CONCEPT
4
VII. CONCLUSIONS
4
A. COMPLIANCE WITH STANDARDS
4
B. DRAINAGE CONCEPT
5
C. STORM WATER QUALITY
5
D. EROSION CONTROL CONCEPT
5
REFERENCES
5
APPENDIX
VICINITY MAP
SITE HYDROLOGY CALCULATIONS
DETENTION POND SIZING AND EMERGENCY OVERFLOW WEIR
EROSION CONTROL
v
r�
FINAL DRAINAGE AND
EROSION CONTROL STUDY
FOR THE
OAKRIDGE BUSINESS PARK, BLOCK ONE, PHASE 2
FORT COLLINS, COLORADO
AND DESCRIPTION
I. GENERAL LOCATION
'
A. Location
The Oakridge Business Park, Block One, Phase 2 project is located in the
southeast part of Fort Collins. It is bounded on the north by Harmony
Road, on the east by Wheaton Drive, and on the south by Oakridge
Drive. The site consists of approximately 4.04 acres of which 2.82 is
'
planned for development for a Medical Center. The site will contain
parking, one building with the option of an addition, and landscaping. It
can further be described as being in the Northwest Quarter of Section 6,
Township 6 North, Range 68 West, 6th P.M., City of Fort Collins,
Larimer County, Colorado.
B. Description of Propert
At present the site is largely undeveloped, and consists mostly of native
grasses with the north east corner containing extensive landscaping. Site
topography is from northwest to southeast at a slope of approximately
' 1.8%. Property to the west and adjacent to the site is currently
undeveloped.
' II. DRAINAGE BASINS
' A. Major Basin Description
The site is located within the Oakridge Business Park Master Drainage
' Plan, and is also a part of the McClellands/Mail Creek Master Drainage
Basin.
DRAINAGE DESIGN CRITERIA
A. Regulations
The City of Fort Collins Storm Drainage Design Criteria is being used for
the subject site. The criteria as established by the Master Drainage Study
1
' for the Oakridge Business Park will also be used for this site.
' B. Development Criteria Reference and Constraints
This site historically drains largely from the northwest to the southeast
' to the intersection of Wheaton Drive and Oakridge Drive. Maximum
release rates, as established by the Master Drainage Study for the
Oakridge Business Park, for this site are 0.2 cfs/acre for the 10 year and
' 0.5 cfs/acre for the 100 year storm events. However, per the Master
Drainage Study listed above, the 10 year storm event passes from the
site at a rate larger than the 0.2 cfs/acre as the regional detention pond
' for the Oakridge Business park has sufficient capacity to detain and
release at the aforementioned rate. In addition, the runoff generated
from the streets internal to the Oakridge site - in particular for this study
' Wheaton and Oakridge Drives - has been accounted for in the Master
Drainage Study for the Oakridge, Business Park. This will be further
' described later in the. report in the DRAINAGE FACILITY DESIGN on page
3.
This site was designated as Basin 340 in the Master Drainage Study for
the Oakridge Business Park. In that Study, the maximum release rate for
the 100 year event for Basin 340 was set at 2 cfs. The calculations
' included at the end of this report will show the maximum release rate for
the 100 year event to be 2.00 cfs placing this design within previously
established and accepted release rates.
' C. Hydrological Criteria
The rational method was used to determine peak developed runoff from
the site. The 10 year and 100 year rainfall criteria, which was obtained
from the City of Fort Collins, is the criteria used for this study.
' For design, the F.A.A. method was used to determine the detention
requirements for this site.
1 D. Hydraulic Criteria
' All calculations within this study have been prepared in accordance with
the City of Fort Collins Storm Drainage Criteria.
' E. Variances from Criteria
No variances are anticipated at this time.
1
' 2
1
' IV. DRAINAGE FACILITY DESIGN
A. General Concept
' The majority of a developed runoff from the site will be conveyed to
the sout ester orner of the project by way of curb and gutter and
' open channe . e average slopes across most of the pavements in the
site is approximately 2%. Runoff from the site will be collected in curb
and gutter in the parking lots and conveyed to a permanent detention
' pond. The majority of the detention for the project will be provided
within is pon . Detained release from this pond will be piped to the
existing storm drain at the intersection of Wheaton Drive and Oakridge
�7"
61 Drive.
Other runoff flows will be detained in the ditch along Harmony Road on
the north side of the site. Detained release from this ditch will be passed
under Wheaton Drive via an existing 5' * 3' elliptical cross pipe to the
' east. The ditch on the east side of Wheaton Drive had been filled at
some point in the past. Because of this situation, flows can no longer he"
removed from this ditchZalong the north side of the site immediately east
' of Wheaton Drive. Detained flows from this basin are released at 0.51
cfs, or 2 cfs per acre as required for the 100 year storm event in the
Master Drainage Plan.
' The combined release rates from these two detention areas will not
exceed the previously accepted release rates from this area for the 100
year storm event. As noted in paragraph B on page 2, the maximum
release from Basin 340 as described in the Master Drainage Study for
Oakridge Business Park is 2 cfs for the 100 year storm event.
' As delineated in the Master Drainage Study referenced above, the runoff
created by the 10 year storm event will be released undetained to travel
to the regional detention pond. This pond, as described in the Master
Drainage Study, has been determined to have enough capacity to release
flows for Oakridge Business Park at 0.2 cfs/acre. See attached page
' from the Master Drainage Study at the end of the Site Hydrology
Calculations in the Appendix for the criteria established for the 10 year
storm events and related detention.
' Likewise, street flows have been accounted for in the Master Drainage
Study and onsite detention is not required per that report. Internal
' streets in the Master Drainage Study are included in Basin 110 and 160,
1 3
F
I
11
7
1
1
the storm runoff of which is directly carried to the regional detention
pond. Therefore, the streets adjacent to this site - namely Wheaton and
Oakridge Drives in Basin 160 of the Master Drainage Report - have not
been taken into account when sizing the onsite detention. A copy of the
Overall Master Drainage Plan has been included in the pocket at the end
of this report.
V. STORM WATER QUALITY
A. General Concept
Beginning in October of 1992, water quality of storm water runoff was
required to be addressed on all final designs. This site will contain a
permanent stormwater detention pond which will serve in the long run
as a means of settling out suspended particles while discharging at a rate
below the predetermined discharge rate.
VI. EROSION CONTROL
A. General Concept
The Oakridge Business Park lies within the Moderate Rainfall Erodibility
Zone and the Moderate wind erodibility Zone per the City of Fort Collins
zone maps. Per the City of Fort Collins Erosion Control Reference Manual
for construction sites, the erosion control performance standards have
calculated.lrajsppropriate measures will be required during and after
construction to control erosion.
All construction activities must also comply with the State of Colorado
permitting process for Stormwater Discharges associated with
construction activities. A Colorado Department of Health NPDES permit
will be required before any construction grading can occur.
VII. CONCLUSIONS
A. Compliance with Standards
All computations within this report have been completed with the City
of Fort Collins Storm Drainage Design Criteria.
9
' B. Drainage Concept
' The proposed drainage concepts presented in this study and shown on
the final grading and drainage plan, adequately provide for the
conveyance and detention of developed runoff for this project. The size
' of the detention ponds will enable this site to develop in conformance
with the Master Drainage Study for the Oakridge Business Park. The
detention ponds for this site will be provided with a minimum of 1' of
' freeboard and emergency overflow outlets in the event the outlet
structures and pipes become plugged.
' In the event groundwater is encountered during construction of any
portion of the site and dewatering is used to install utilities, a State of
Colorado Construction Dewatering Wastewater Discharge permit will be
required.
' C. Storm Water Quality
This site will contain a permanent stormwater detention pond which will
serve in the long run as a means of settling out suspended particles while
discharging at a rate below the predetermined discharge rate.
' D. Erosion Control Concept
Per the. City of Fort Collins Erosion Control Reference Manual for
' Construction Sites, the erosion control performance standards have been
calculated and appropriate measures will be required to control erosion
from the site.
REFERENCES
Storm Drainage Design Criteria and Construction Standards by the City of Fort
Collins, Colorado, May 1984, revised March 1991.
2. Erosion Control Reference Manual for Construction Sites by the City of Fort
Collins, Colorado, January 1991.
' 3. Master Drainage Study for the Oakridge Business Park, by RBD Inc. Engineering
Consultants, June 1990.
1 5
APPENDIX
11
VICINITY MAP
7
iL
1
1
1
r-■
CC
O
O
w
N
O
YI
a
WLU
� H
0 �n .
� Q
Q
S
d% �0 NOld3�
'3Ad Ad 31 'S
0
a
DR. o
'3Ad 3031100 'S
w
�g0
a
I
11
1
SITE HYDROLOGY CALCULATIONS
1
1
CLIENT ✓ i' JOB NO.
INC PROJECT �<<%G�C / _ /�ii/ CALCULATIONS FOR _,s7z 2�n
41
Engineering Consultants MADE BY.5dDATE �EC�ECKEDBY- DATE -SHEET OF /Z_
%e 3—�YLs7��
/F
IIII if1 r
1192 ! %3�'S/h�-S
II I
-•LI (3.
'If i I,I
L
i I
I
If
- ..
f
1�/1
l
���
I� I I I I
I I
, r
JL
I ,
I
1�L
T1
I I
�
,
t _
f
I
I
-
I
_
_
v27/�D'n/ . SiG B
1..
1
1
�.a2 •-tea 38, 9'YG
vw2c_ I iGK/n/� Gr 7i8 _
_ _
_
/ ?9s
{ 6
f
.. '
t�C S2 G
•
9
a
/1/
(
jrs/Nus
�..
1
ym
•
I:. .
f 1 f,
I
�
RMINC
Engineering Consultants
CLIENT ��JCI' JOB NO. S3-O�t%
PROJECT i4 45KIC /'114 CALCULATIONSFOR—,S?VYr-A .
MADEBYV& DATEI NECKED BY DATE SHEET 0_OF -Z
L
I I I
t f
r
;
_
' ' I
%3a Sr�r /A- �r�i2�OI✓l � /3�l/t
1 I
I �
i �
•-� —
I
}. .-4...-_—
I�
I
j
r i
L:t:.� .'...3_ .,3 r231 __�.i� I
� ; -�
-ate•-��-'--:
,c _
I I j
I LI
1_
,Iv%1cc
...
Q ^ ' 77
de—
i
�SSvr+To /4�e7�Y/ 3���Gf
L4H.NS
J.
`
_ T
-1 / v�ri3
' '
I I I
�crrt�,
,
lfk
..-
_ _
1
_
I
1 ..
I
_
_
/
r
_
I
'
j
SS V /'9 t� /vC [��t9 /L S /
/1 c.✓/�/_: T
, 1
+ V
I
j
'I1F
i I
'
_
1
_
< 2/
i -
2
I
1
1
.- /
- I2;
J.
_
I ,
J.
.... .�.:.
".-.... f
_
I
f
1
1 011SOINC
Engineering Consultants
1
1
1.
1
1
1
1
1
1
1
1
1
1
1
1
1�
1
CLIENTy JK- /'- JOB NO. '!!�3 r O� d
PROJECT /6G.0 I 12/f;!27 CALCULATIONS FOR S�D2r�1
MADE B K$ DATEi *CHECKED BV DATE SHEET J OF /Z
/fir itYz�Nc,.
( (vuSf��c �D.L EC
I
✓3
/�✓
LI J
'
".a.as
I '
I
�rtG vr/
e . c �.z�..✓� c t s'Zvb � ,ro.�.
L�a-c
� I
, L �-
!
m v�/i
1
it
I � I
_ J Q ioo
,?
03
I
_
J
_ 1
10
�O.f%G2i/JG� QrJls'inle'8
_
loo
I
..
-----
I
�
�
�S'
{
,
-!.., ..
L
_. /%]�"TT.E'!2 /:✓!
/ !�/ [ -. � '. r I ��! Fd..:G 'C"�-G'
�. - [Sj�S �i<1/
�/ c9d 7..
i _ ! ._.
y
I
I
yyo�
I +
r
L._-
/r
LL, I
I
I :
e,
o
I
----------------
I
UC
�
�
I
RMING
Engineering Consultants
CLIENT A7-- JOB NO. 1e9_y__0_30
PROJECT Beece CALCULATIONS FOR
MADE By DATEM6� -CHECKED BY DATE -SHEET2�_/_ Of
259�0_ 7-/17
T
7
-- ----- ------
L
__ 4 T
i.7
1
F-i
rj
T
j ......
. .......
-.7 1
........ -
Z7 ,
- - -- - -- - - -
4- - -
7
..- p i
_7
_4
......
-- - --------
- - - - - - - - - -
I p
_T_
I
....
..... . ......
------ -- -- -
.....
_4
---- - --- - - - ------
i.
-A
4
.. ....
111
4 - - - - - -
- - - - - - - - - - - -
7-
- - - - - - - - - --
7r
4-
T:ADNC
Engineering Consultants
I
11
I
I
I
I
I
I
11
I
I
I
I
I
11
I
CLIENT 11,00pe 09-- JOB NO.
PROJECT ae-AKE 17, Alre-07 CALCULATIONSFOR
MADEBYS4(-DATE-7/zgeln�.,CHECKED By- DATE -SHEET-,..'��DF -Z7,
r7-7
4-
L
--L•- J.
47
-7
-Y4
T j
T
j L
7-
L
-1--j-
j J' ....
.. .
r
j-1 --- i
4,-
_1
. ...........
'Z
TT 7
---------- --- ----- - ----
- - - - - - - - - .... .. .. - ------- ----- j-
.....
L-
...... - ------------ - - - - — -
- - - -
- - - - - - - - - -
-- - --- -----
.ems
-7
- -
--------------
-- --------
----
---- ..........
-L- L -j
- - - - - - - - - - - -
777-
7
00
4
4
. .. ------
- - - - - - - -
.- / %
.....
-- ----------
yy �f.�//fry � 0,2/, ♦'G C-
�b /23
' ,
� 1 {.! ' L �'
��,
Ir.-� ,
4 -
..............
. .. . . . . . .. . ... ...
-- ----
- - - ------- - - ---------- -
oe
I
I
I
j
I
I
I
I
I
I
I
I
I
I
I
I
I
I
CLIENT JOB NO. f830
NC PROJECT RZOC-e ~e CALCULATIONSFOR M221t:Cwj
Engineering Consultants MADE BYge4 DATE CHECKED BY -DATE -SHEET -/,,-,-OF
_4
. ................
------- ---
T
-- --------
4.
4�
-T
.... ... ..... .....
. .....
j.-
77
T
- - - - - - - - - -
1-T
A
:
i
........ .... , I
.. .... ... .
.. ...... ..
-- ---- _J i._! L -
...... ....
----- -- -----
..........
- -----------
4
A L
7
t ---------- -----
-----------
4
- - - - - - - - - - -
--- - ------- -
L 1i
------------
-
ZE
i L
7R'
............
If
7 - — - - - - - - - - - - - - - - - - -
---- --- -------
1 .2
- - - - - - - - - - -
4 ---
.. ..... .........
q I
J- - - - - - - - - - - --
OIL e J- 1
. . . . . . . . . .
L .
_I
J
- - - - -
- - - - -
i
1 RmNG
Engineering Consultants
1
1
1
1
1
11
1
1
11
1
1
1
1
1
CLIENT 1` JOB NO.-/B.3 -O�-3
PROJECT '71 C OCk O'CfjN�LIJr, %�/t CALCULATIONS FOR 5222a hn
MADE BY�v�,DATE ���1"/ CHECKED BY DATE SHEET
Z0F
'/�r3`rn ,
'
I
i.�iF . �fo
f-o2 �.¢-cam}
1
i3i+`s/•�%,_
K
�-f I I 1 � ' '- I IT', � 7 '�--
I
I 1
I
i
i I
_ /
J
I
45
1
_
120N9+
�AoVF�tL ��/Yy 6T/J�
�y G v 2
t �i1 PT7fGIYJ $�y i
f
rr .
J. _41
l
�
I
I
I
I.-.
I ,
I
i
1 ,
}
I
,-
itfs
,�o
l Q, - D, _17�2.8�)
i of
4r787s
1
...
-.
..:. :.
._ ----- {
i
3 `I a?
/o d 7zi
Y 7 7� 13 03 i
1 i_ji3
1-------------
//2>
CLIENT Af /, ilc JOB NO. OZ�
RMINC PROJECT AZLX0'06!e,_ CALCULATIONS FOR -CYd, A%,7
Engineering Consultants MADE BTc1cff_DATE Z�CHECKED BY- DATE SHEET o OF %Z
I
I
I
No Text
INTERPOLATED VALUES FOR 100 YEAR INTENSITIES
Tc Value 6U,/41r-,
5.00
9.0
5.10
9.0
5.20
8.9
5.30
8.9.
5.40
8.9
5.
8.8
�w0
5.6050
8.8
5.70
8.7
5.80
8.7
5.90
8.7
6.00
8.6
6.10
8.6
6.20
8.6
6.30
8.5
6.40
8.5
6.50
8.5.
6.60
8.4
6.70
8.4
6.80
8.4
6.90
8.3
7.00
8.3
7.10
8.2
7.20
8.2
7.30
8.2
7.40
8.1
7.50
8.1
7.60
8.1
7.70
8.0
7.80
8.0
7.90
8.0
8.00
7.9
8.10
7.9
8.20
7.8
8.30
7.8
8.40
7.8
.8.50
7.7
8.60
7.7
8.70
7.7
8.80
7.6
8.90
7.6
9.00
7.6
9.10
7.5
9.20
7.5
9.30
7.5
9.40
7.4
9.50
7.4
9.60
7.3
9.70
7.3
9.80
7.3
9.90
7.2
10.00
7.2
MASTER
DRAINAGE
STUC
w4io
FOR
Th
��
OAKRIDGE
BUSINESS
PAR
I
.1
31U
YES
Offsite from north of Harmony
300
YES
Offsite from west to Lemay
290
YES
Existing
280
NO
Street
270
YES
260
YES
250
YES
Existing
240
NO
Downstream street capacity.is OK
230
YES
220
YES
�.
210
NO
From sump in Innovation to channel
200
NO
Possible YES; Direct to Pond
120,
NO
Possible.YES; Includes Comlinear
110
NO
Internal street system
The 10 year storm
model did
not include any site specific detention
for the Oakridge
site. The
above results indicate that control at
the regional detention pond is adequate to bring the 10 year �-
release rate below the allowable 0.2 cfs per acre discharge. This
includes
offsite
Basin 300.
2.2.2 Flow Characteristics
STREET SYSTEM FLOW
DEPTH
xi?
Page 8 of Appendix A is
a sorted list of all the basins and
conveyance elements with their respective flow depths.. The internal
Ii
street system was
City of Fort
evaluated
according to allowable flow depth. The
Collins criteria states that14 both local and
collector streets may have
the
an 18" depth of runoff in the gutter for
major (l00 year) storm event and arterial streets are only
allowed a depth of 0.5' above the crown. There are no arterial
streets internal to the Oakridge site. For comparative purposes
only, the above mentioned evaluation is based on the arterial
standard.
There are only three streets that exceed 0.51in crown depth and are
located at the downstream end of the basin (see enclosed Drainage
Plan). This exceedance is only 0.04 feet in each case. They are
Elements 21 (Innovation Drive), 12 (internal future_ street near
Comlinear) and 7 (Wheaton Drive). Innovation Drive and Wheaton
Drive have been built. All the internal streets have 100 year water
surface levels below the allowed 18" standard and present no
hinderance to the passage of emergency vehicles.
Element 12 is associated with Basin 120 (Comlinear) and was
evaluated at a minimum grade of 0.6% slope.
DETENTION POND SIZING
AND EMERGENCY OVERFLOW WEIR
----------------------------------------
DETENTION POND SIZING BY FAA METHOD
' DEVELOPED BY
JAMES C.Y. GUO, PHD, P.E.
DEPARTMENT OF CIVIL ENGINEERING
' EXECUTED ON 07-25-1994 AT TIME 18:56:03
PROJECT TITLE: BLOCK ONE, PHASE II
**** DRAINAGE BASIN DESCRIPTION
***** DESIGN RAINFALL STATISTICS
BASIN ID NUMBER =
BASIN AREA (acre)=
RUNOFF COEF =
7
1.01
0.27
DESIGN RETURN PERIOD (YEARS) = 100.00
' INTENSITY (IN/HR) -DURATION (MIN)
TABLE
IS
GIVEN
DURATION 5 10 20 30
40
50
60 80 100 120 150
INTENSITY 9.0 7.3 5.2 4.2
3.5
3.0
2.6 2.1 1.7 1.5 1.2
1
1
I
180
1 . 0-1-- Liv% F• t .
***** POND OUTFLOW CHARACTERISTICS: C,h) S1
MAXIMUM ALLOWABLE RELEASE RATE = 57 CFS
OUTFLOW ADJUSTMENT FACTOR = .89
AVERAGE RELEASE RATE _ .5073 CFS
AVERAGE RELEASE RATE = MAXIMUM RELEASE RATE * ADJUSTMENT FACTOR.
***** COMPUTATION OF POND SIZE
RAINFALL
RAINFALL
INFLOW OUTFLOW
REQUIRED
DURATION
INTENSITY
VOLUME VOLUME
STORAGE
MINUTE
-----------------------------------------------------
INCH/HR
ACRE -FT ACRE
-FT
ACRE -FT
0.00
0.00
0.00
0.00
0.00
5.00
9.00
0.02
0.00
0.01
10.00
7.30
0.03
0.01
0.02
15.00
6.25
0.04
0.01
0.03
20.00
5.20
0.04
0.01
0.03
25.00
4.70
0.04
0.02
0.03
30.00
4.20
0.05
0.02
0.03
35.00
3.85
0.05
0.02
0.03
40.00
3.50
0.05
0.03
0.03
45.00
3.25
0.06
0.03
0.02
50.00
3.00
0.06
0.03
0.02
55.00
2.80
0.06
0.04
0.02
----------------------------
THE REQUIRED
POND SIZE
=-------------------
= 2.703412E-02`�`ACRE-FT
m
0•0_
THE RAINFALL DURATION
FOR THE ABOVE
POND
STORAGE= 25
MI TES
wobwAll�.•
��"
ova"
p�
v
I
-------------------------------------------------------=----------------------
------------------------------------------------------------
DETENTION POND SIZING BY FAA METHOD
' DEVELOPED BY
JAMES C.Y. GUO, PHD, P.E.
DEPARTMENT OF CIVIL ENGINEERING
' EXECUTED ON 07-21-1994 AT TIME 07:42:41
PROJECT TITLE: BLOCK 1, PHASE II
**** DRAINAGE BASIN DESCRIPTION BASIN ID NUMBER =
BASIN AREA (acre)= 3.03
RUNOFF COEF = 0.72
***** DESIGN RAINFALL STATISTICS DESIGN RETURN PERIOD (YEARS) = 100.00
'INTENSITY (IN/HR) -DURATION (MIN) TABLE IS GIVEN
DURATION 5 10 20 30 40 50 60 80 100 120 150 180
INTENSITY 9.0 7.3 5.2 4.2 3.5 3.0 2.6 2.1 1.7 1.5 1.2 1.0•o-c,>7 r.t.
POND OUTFLOW CHARACTERISTICS:
MAXIMUM ALLOWABLE RELEASE RATE = 1.51 CFS
OUTFLOW ADJUSTMENT FACTOR = 1
AVERAGE RELEASE RATE = 1.51 CFS
AVERAGE RELEASE RATE = MAXIMUM RELEASE RATE * ADJUSTMENT FACTOR.
***** COMPUTATION OF POND SIZE
RAINFALL RAINFALL
INFLOW
OUTFLOW
REQUIRED
DURATION INTENSITY
VOLUME
VOLUME
STORAGE
MINUTE
INCH/HR
ACRE -FT
ACRE -FT
ACRE -FT
'
0.00
0.00
0.00
0.00
0.00
5.00
9.00
0.14
0.01
0.13
10.00
7.30
0.22
0.02
0.20
'
15.00
6.25
0.28
0.03
0.25
20.00
5.20
0.32
0.04
0.27
25.00
4.70
0.36
0.05
0.30
30.00
4.20
0.38
0.06
0.32
35.00
3.85
0.41
0.07
0.34
40.00
3.50
0.42
0.08
0.34
45.00
3.25
0.44
0.09
0.35
'
50.00
3.00
0.45
0.10
0.35
55.00
2.80
0.47
0.11
0.35
60.00
2.60
0.47
0.12
0.35
'
65.00
2.47
0.49
0.14
0.35
70.00
2.35
0.50
0.15
0.35
75.00
2.22
0.51
0.16
0.35
'
80.00
2.10
0.51
0.17
0.34
85.00
2.00
0.52
0.18
0.34
90.00
1.90
0.52
0.19
0.33
95.00
1.80
0.52
0.20
0.32
'
100.00
---------------------------------
1.70
0.52
0.21
0.31
THE REQUIRED
POND SIZE
3528427
-----------------
CRE-FT 4
'
THE RAINFALL
DURATION
F E AEUVE
POND
STORAGE= 70 MINUTES
------------------------------- ---------------------------
------------
DETENTION POND SIZING BY FAA METHOD
' DEVELOPED BY
JAMES C.Y. GUO, PHD, P.E.
DEPARTMENT OF CIVIL ENGINEERING
' EXECUTED ON 07-25-1994 AT TIME 19:01:24
PROJECT TITLE: BLOCK ONE, PHASE II
2nd ITERATION)]g
**** DRAINAGE BASIN DESCRIPTION
BASIN ID NUMBER =
�B
BASIN AREA (acre)=
3.03
RUNOFF COEF =
0.72
DESIGN RAINFALL STATISTICS
DESIGN RETURN PERIOD
(YEARS) =
100.00
INTENSITY (IN/HR) -DURATION (MIN) TABLE IS GIVEN
'DURATION
5 10 20 30 40
50 60 80 100
120 150
180
INTENSITY 9.0 7.3 5.2 4.2 3.5
3.0 2.6 2.1 1.7
1.5 1.2
1.0t Civ7 F.C,
t ***** POND OUTFLOW CHARACTERISTICS:
MAXIMUM ALLOWABLE RELEASE RATE = 1.43 CFS
OUTFLOW ADJUSTMENT FACTOR = 1 S
AVERAGE RELEASE RATE = 1.43 CFS
AVERAGE RELEASE RATE = MAXIMUM RELEASE RATE * ADJUSTMENT
***** COMPUTATION OF POND SIZE
-----------------------------------------------------
RAINFALL
RAINFALL
INFLOW
OUTFLOW
REQUIRED
DURATION
INTENSITY
VOLUME
VOLUME
STORAGE
MINUTE
INCH/HR
ACRE -FT
ACRE -FT
ACRE -FT
----------------------------------------------------
0.00 0.00 0.00 0.00 0.00
5.00
9.00
0.14
0.01
0.13
10.00
7.30
0.22
0.02
0.20
15.00
6.25
0.28
0.03
0.25
20.00
5.20
0.32
0.04
0.28
25.00
4.70
0.36
0.05
0.31
30.00
4.20
0.38
0.06
0.32
35.00
3.85
0.41
0.07
0.34
40.00
3.50
0.42
0.08
0.35
'
45.00
50.00
3.25
3.00
0.44
0.45
0.09
0.10
0.35
0.36
55.00
2.80
0.47
0.11
0.36
60.00
2.60
0.47
0.12
0.35
'
65.00
2.47
0.49
0.13
0.36
70.00
2.35
0.50
0.14
0.36
75.00
2.22
0.51
0.15
0.36
80.00
2.10
0.51
0.16 0.35
'
85.00
2.00
0.52
0.17 0.35
90.00
1.90
0.52
0.18 0.34
95 00
1 80
0.52 0.19 0.33
'---100_00------1_70----- 0.52 0.20 0.32
----------------
THE REQUIRED POND SIZE .3605562 CRE-FT e
' THE RAINFALL DURATION OR TH OND STORAGE= 70 MINUTES
Yy c (S 0�_
FACTOR.
00
+J
c0
O
o .
o
w
u
1 '
o^
..rd
!"
FF
w
r
C�
M
y
}
•-
O
J i p.
N
:1 Q.
+
/-T
0
dab
M �
b
of
0
w
N
0
O
f.j
u
C)
G.
Z
o
O
O .I
j-
oo d
N rn
Cd; LD d N.
Co
a) a) rn
CDo oo, oo . o0 00
0
o
O CD CD
o a o o o
I
x — .10'.0*ej
quaui-4snrpv A4.OIJ0
•
o
I
I
1
BLOCK ONE, PHASE II, OAKRIDGE BUSINESS PARK
pDETENTION POND FOR IBASIN A
' RATING CURVE
11
Elev.
Area
Area
Storage
Cum. Stor
ft.
sq.ft.
ac.
ac.ft.
ac.ft.
78
309
0.01
0
79
1143
0.03
0.02
0.02
79.5
1143
0.03
0.01
80
2387
0.05
0.02
0.05
81
3693
0.08
0.07
0.12
IJ
1
1
i
1
1
1
L
1
I
.1
11
1
.1
BLOCK ONE, PHASE II, QAKRIDGF RURI ESS PARK
--DETENTION POND FOR ASIN B
RATING CURVE
Elev.
Area
Area
Storage
Cum. Stor
ft.
sq.ft.
ac.
ac.ft.
ac.ft.
73.25
1066
0.02
0
0
74
1805
0.04
0.02
0.02
75
2385
0.05
0.05
0.07
76
4931
0.11
0.08
0 5
77
13213
0.30
0.20
0.36
1
RBD INC. ENGINEERING CONSULTANTS
OVERFLOW WEIR SECTION FLOW DATA
BLOCK ONE, PHASE II
WEIR COEF.
3.400 : `f -- fires+-� il,.i< 7� i3124-c� rL
STA ELEV
100.0 78.00
200.0 78.00
207.5 77.00
215.0 78.00
315.0 78.00
ELEVATION
DISCHARGE
3iZ
(feet)
(cfs)
Q -eGH
77.00
0.0
77.10
0.1
77.20
0.3
%7 37 77.30
0.9
77.40
1.8
77.50
3.2
77.60
5.0
77.70
7.4
77.80
10.3
77.90
13.9
78.00
18.0
7 7 m o
J
11
1
11
h�
EROSION CONTROL
1
RAINFALL PERFORMANCE STANDARD EVALUATION
PROJECT: acock, o^nr� STANDARD FORM A
COMPLETED BY: -5 • C. i3 . DATE: rx, c
DEVELOPED
ERODIBILITY
Asb
Lsb
Ssb
Lb
Sb
PS
SU9BA§IN
ZONE
(ac)
(ft)
M
(feet)
M
($)
...........y
%Or.
Qlc
49 -e4-
+qNT�t-Yf
DYij-PCB
' MARCH 1991
B-14 DESIGN CRITERIA
f
i
i
r-
r
I
1
t
I
J
EFFECTIVENESS CALCULATIONS
PROJECT: o�K2���r; ,3CoCK e../�, P*Z:r STANDARD FORM B
COMPLETED BY: DATE:
Erosion Control C-Factor P-Factor
Method Value Value Comment
fSV-,A/3G/S,"c 0 0,08
4IZA ss
/3A 2 r% 2 ov.vo
MAJOR
PS
SUB
AREA
BASIN
BASIN
(Ac)
CALCULATIONS
jg �
�. �,y
���ss ,��� = �• 9y ,fc-.. .
fc re/L - /• 00
vO
C:5
�sj� r � 9.8 • �o
/D/ttvrw i iv-f o
' MARCH 1991 8-1S DESIGN CRITERIA
RAINFALL PERFORMANCE STANDARD EVALUATION
PROJECT: 0,,F1rC14 4 4 OC IC STANDARD FORM A
COMPLETED BY: C.Q.DATE:
DEVELOPED
ERODIBILITY
Asb
Lsb
Ssb
Lb
Sb
PS
SUBBA§IN
ZONE
(ac)
(ft)
M
(feet)
M
M
70
s. 8
Bo
oo -
MARCH 1991
8-14 DESIGN CRITERIA
I
I
7
L
EFFECTIVENESS CALCULATIONS
PROJECT: 0/.ceo,,p4 e ve ae acit ^+�14 sr -2r STANDARD FORM B
COMPLETED BY: DATE:
Erosion Control C-Factor P-Factor
Method Value Value Cominent.
e-12,to,4 0, 5'j- a 0
0.08
-- --- -- =.-4 -
-(50
.Sole -
MAJOR
PS
SUB
AREA
BASIN
BASIN
(Ac)
CALCULATIONS
4.e,f c Ire
5>
7.'
&,:7 7
1,6 gg ,Z 0 6r, yg)
Ma
MARCH 1931,
8-15
DESIGN CRITERIA
3
c
CONSTRUCTION SEQUENCE
I Mai
PROJECT: 4µK erc, G�i3roeii Qivr� P.r�RSe�11 STANDARD 3FORM C
SEQUENCE. FOR 19. ONLY COMPLETED BY: ,g,, c. f*sa c L DATE:. o
Indicate by use of a bar line or symbols when erosion control measures wiIT.'66,installed.
Major modifications to an approved schedule may require submitting a new schedule for
' approval by the City Engineer.
ix
YEAR
MONTHIAIsI_OI�/I r�IJIF.Ir?I�I::Ia=4,:I5'
' -------j----1---= --1: -
------------------------ I----}----} -.{
OVERLOT GRADING I-1 I i I I I I ' I:-' I :. 1 T----�
' WIND EROSION CONTROL
Soil Roughing
Perimeter Barrier
Additional Barriers
Vegetative Methods
Soil Sealant
Other
,-
RAINFALL EROSION CONTROL
' STRUCTURAL:
Sediment Trap/Basin
Inlet Filters
Straw Barriers
Silt Fence Barriers
Sand Bags
' Bare Soil Preparation
Contour Furrows
Terracing
Asphalt/Concrete Paving
' Other
' VEGETATIVE:
Permanent Seed Planting
Mulching/Sealant
Temporary Seed Planting
' Sod Installation
Nettings/Mats/Blankets
Other
I =
STRUCTURES: INSTALLED BY
' VEGETATION/MULCHING CONTRACTOR
' DATE SUBMITTED
P, DI/SF-C:1989
MAINTAINED BY
N0. DeDATE
HARMONY ROAD EXISTING 5XT ELLIPTICAL
Tt� _ BOB PIPE. FIELD FIT��_� ��'� �� ' a 3/e DEA ORIFICE PLATE.
F
81 ., .........._
19 RETAINING
WALL
I I
1 ,
1
HARMONY MEDICAL CENTER
1 10,000 SQ. F I. 4 16,000 S0� FT. 1
1 EXPANSinN E.F. ELEV.- 4980.Y5
I
1 RETAINING WALL
I RE'. ARCH
I I
I I
I
I
t- -
.-
_; �-:-
I
I
j
RE. ARCH
I
�1
II
}
l
x
1
I
1
'�—
II
SIDEWALK CHASE
'
nitr
I
FOR ROOF DRAINS
k
0
m
0111, ,
O
'
7-I 1CURB
I
I L...
9
II
m
v1. P
rp
HIT
eRoNF
I — WIDE
1 -ON F
�tt
I
FUTURE FUTURE
PARKING 4,000 SO.FT. 1 I 18" FLARED
PAD ail. END SECTION
WEE 5-1/4 ORIFICE
v ht Rj PLATE
L 1
9 ` EXISTING 'B' RCP
V p ! re n RE DMLOCA E STUB.
—JT_
/ • - D- '•=B <?. 1 FI FO EF NEED ENDS SECTION
PIPE
® .TR I / '�°` V >b — FROM CORE INLET
OES
SIR
- - 1- SSR 1 N01 EXTEND AS SHOWNIE
3
,. a _" __ 15 SHOT _ 15,
n - STORM �.. - OVERFLOW
OX e_ �_ .... WEIR O ELEV }
9y
- OAKRIDGEDRIVE ___�--- ------- --- ;'
LOT
�F SITE SKIT STATE
For Be,
pnraap
ama Noy
If
E
HOTEL Sa
ANSI
C"
MOOTA
a) BE OUR
.muRXIAMMm WA X@R1t XkR
a/8' AMEX CONTINUE qXR
POR9 OUTLET
MPM SCE
IT
AUG,1 1994 E3-030
Nn+
NOTE.
OTY SHALL NOT BE RESPONSIBLE FOR VAINRNANCE of D.NSITE STORY
DRAINAGE EAZIUNES. NOR ME OFFSHE SNALE(S) SS0*A W. THESE
FLANS AS ME DEVELOPER WALL BE RESPONSIBLE ME CITY ALL NOT
MAINTAIN IRRIGATION SWAIfS/DITCHES, OR PONDS.
DEVELOPED SITE HYDROLOGY
LEGEND
W
III
SCALF 1'=30'
EXISTING CONTOUR
PROPOSED CONTOUR
PROPOSED BASIN BOUNDARY
ePROPOSED BASIN NUMBER
O SAC BASIN AREA IN ACRES
CONCENTRATION PT,
UIRECTION OF FLUX
9RAW BALE CHECK DAM
GRAVEL INLET FILTER
L' EXISTING SPOT ELEVATION
SHIP— PROPOSED SPOT ELEVATION
FF FINISHED FLOOR ELEVATION
FLOWLINE
SEDIMENT FENCE
11511 SANITARY MANHOLE (EXIST)
Ci STORM DNAIN MANHOLE (EXST)
City
of Fort Colliln'Colorado
DRAINAGE Sams.
_
UTMR
PLAN APPROVAL
ON —SITE DFTFNTON
u0,
A
HASIN A
APPKo.i
_
Dlrectar of EMH^'nng
Date
SE
.1C Ei
RF]Nr H
C"FrKtC 0
RT
Meter N YeateaeteT pNllty
Date
DETENTION SUN•n <RY
Cn EGr,LU
US
_
BASINS DRAINED:
A
R
9tunaaeter Duty
-Date
MAIL RELEASE RATE.
O.ht
AC
1 43
CHECKEU
HT
REQUIRED
D oX
AC
0.35 AD Fr
PC
Yer6 k AeoeeUon
_
Date
PROVIDED
VOLUME PROVIDED.
U.12
0.30 AC Fi.
SURFACE PF
SO
4C
AC
CHELHED
BY
IOC vR WY
497
a9T9
a9P
497
Date
CHECKED
BY.
Engineering Consultants I OAKRIDGE BLOCK ONE P.U.D., SECOND FILING
' - � 1,;42FORT COLLINS, COLORADO
-Date—
GRADING, DRAINAGE AND
EROSION CONTROL PLAN 5 4