HomeMy WebLinkAboutDrainage Reports - 06/01/2012 (2)TST
760 Whalers Way
Bidg C, Suite 200
Fort Collins. CO 80525
970.226.0557 main
303.595.9103 metro
970226.0204 fax
ideas@tstinc.com
www.tstinc.com
TST, INC. CONSULTING ENGINEERS
City of Ft_ Collins prov Plans
Approved By. � May 16, 2012
Date 6- 1 1
Mr Wes Lamarque
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
RE: Seven Lakes PUD Phase II Subdivision — Amended Site Plan (OCR Site)
Supplemental Drainage Report
PN 0978.0010.00
Dear Wes:
Please find included in this revised letter report a supplemental drainage analysis for the amended
site plan for the Orthopedic Center of the Rockies (OCR) site. The amended site plan includes an
addition to the existing building to allow additional exam rooms and administrative space, and an
expansion of the parking lot in the northwest portion of the site. This report has been updated to
include the information required for the Floodplain Use Permit.
This supplemental report evaluates the drainage components for the proposed changes to the
existing parking lot area and drainage facilities. Documents reviewed include the Final Drainage
Report for the Seven Lakes PUD Phase I I Subdivision, dated January 5, 1989; prepared by Stewart &
Associates, Inc. Excerpts from that report are included here for reference.
Floodplain
This site lies within the FEMA 100-yr Spring Creek Floodplain as shown on the FIRM (Flood
Insurance Rate Map), Panel 0983H, Map Number 08069C0983H, map revised May 2, 2012. A copy
of the FIRMette is included within this report. The existing building and proposed building expansion
finished floor elevations are above the base flood elevation by a minimum of 0,50'. The base flood
elevation along the western edge of the building is 4901.02 and the finished floor elevation of the
existing building and proposed building addition is 4901.86. An exhibit showing the base flood
elevation interpolation is included in this report.
Building Addition
The proposed building addition is for additional exam rooms, administrative areas and the expansion
of the physical therapy area. The foundation construction will consist of slab on grade construction
and the elevation will match the finished floor elevation of the existing building of 4901.86. The
finished floor elevation (lowest floor elevation) is above the regulatory flood protection elevation of
4901.52 and in compliance with Chapter 10 of the City Code. The table below summarizes the
finished floor elevation and associated flood elevations.
Description
NGVD 29
NAVD 88
Proposed Finished Floor Elevation
4901.86
4904.86
FEMA BFE at upstream end of structure
4901.02
4904.02
Regulatory Flood Protection Elevation
4901.52
4904.52
Lowest Floor Elevation
4901.86
4904.86
HVAC Equipment
4909.86
4912.86
OCR Supplemental Drainage Report Page 1
A Floodplain Use Permit will be submitted at the time of the building permit application and a FEMA Elevation
Certificate shall be completed and approved prior to the certificate of occupancy is issued for the building addition.
Existing Drainaqe Patterns
Existing basin 1 is 3.35 acres and includes the western portion of the existing parking lot and OCR building.
Stormwater runoff in this basin basically sheds from the OCR roof to the west, and then to the northeast via overland
flow and across the parking lot. Runoff is intercepted in two 5' type R inlets located on the eastern edge of the
existing parking lot. Runoff that is not taken into the inlets overtops the sidewalk and flows toward the wetland
channel in existing basin 3. (The existing basin 1 is comprised of proposed basins 1, 1.1 and 1.2.)
Existing basin 3 includes the wetland channel along the northern property line and a small portion of the OCR
building on its northern side. This basin is 1.10 acres. Runoff from this basin sheds from the roof and overland flow
on the north side of the OCR building into the wetland channel that drains to the east. (Proposed basin 3 is a small
portion at the very upstream stretch of existing basin 3.)
The existing basins are illustrated on the Drainage Plan prepared by Stewart & Associates that is included with this
report.
Proposed Drainage Patterns
The proposed parking lot addition, shown in proposed basins 1.1 and 1.2 will redirect the drainage pattern in the
existing basin 1. Proposed basin 1.2 redirects stormwater runoff toward the north to a proposed rain garden. The
amount of developed runoff in the 100-yr storm directed into the rain garden is 4.97 cfs. This runoff is intended to
infiltrate in the rain garden. However, there is a weir overflow at the east end of the rain garden to accept and direct
runoff toward the existing 8" storm pipe and wetland channel in basin 3. Runoff that does not infiltrate at the rain
garden will follow the existing drainage patterns and into the wetland channel.
Proposed basin 1.1 is still directing runoff toward the existing parking lot and storm inlets. The amount of area now
draining to the existing lot is reduced by 0.48 acres. The amount of developed runoff (attenuated flow from basins 1
and 1.1) at design point 1 is 21.9 cfs for the 100-yr storm. This is an overall reduction of 1.4 cfs in this basin, as the
existing basin 1 generated 23.3 cfs for the 100-yr storm (according to Stewart & Associates calculations).
Inlets
There is an existing type 13 inlet located at the western side of basin 1, and two existing 5' type R inlets located in
basin 1 on the eastern edge of the existing parking lot. These inlets intercept a portion of the minor storm, while the
remaining runoff flows to the east and north in the parking lot and overtops the sidewalk to follow existing drainage
patterns and spill into the wetland channel located north of the building. As stated earlier, the proposed condition
reduces the amount of runoff toward these inlets slightly; however, runoff will still overtop the sidewalk at design point
1. The amount of runoff anticipated to be intercepted in each of the type R inlets is 4.9 cfs in the 100-yr condition.
Since this area is within the 100-yr floodplain, the amount of runoff that will overtop the curb and sidewalk at design
point 1 was not calculated at this time.
Storm Sewer
There is an existing 8" diameter storm pipe located below the sidewalk at design point 3. This storm pipe accepts
approximately 1.73 cfs. Additional runoff in this area overtops the pipe and sidewalk.
Rain Garden
The proposed rain garden provided at the north end of the new parking lot is intended to accept stormwater runoff for
infiltration into the granular sub -base and to provide the water quality capture volume (WQCV) sufficiently sized for
the basin draining to it. An emergency overflow weir will be provided at the east end of the rain garden to allow for
overtopping directed toward the wetland channel in the event that infiltration in the rain garden fails. The tributary
area for the rain garden is 100% impervious and approximately 21,000 sq. ft. Thus the required WQCV for a 12-hour
OCR Supplemental Drainage Report Page 2
drain time is 700 cu. ft. The provided rain garden size exceeds the requirement and is approximately 1258 cu. ft. in
volume. The base elevation of the rain garden is 4899.25 and the top elevation is 4900.25. A detail of the rain garden
is provided in the construction drawing plan set.
A Subsurface Exploration and soil percolation evaluation was completed by Earth Engineering Consultants, Inc.
(EEC) for the rain garden concept and the results of this evaluation have been included in this report.
The overflow weir elevation is also set at elevation 4900.25. The width of the weir is 5' with a crest length of 3'. The
weir calculations show that this size of weir will sufficiently pass the 100-yr developed flow from basin 1.2 of 4.97 cfs
to the downstream channel.
Summary
The stormwater runoff from the amended site plan at OCR has met the design requirements set forth by the City of
Fort Collins and has incorporated water quality measures prior to the runoff entering the existing wetland channel,
thus achieving better stormwater quality than existed prior to the building and parking lot additions.
Please refer to supporting exhibits, calculations and the proposed drainage plan included in this report.
TST, INC. CONSULTING ENGINEERS
Sincerely, 01�/Wo AAV�
Heather McDowell, P.E.
Cc: Mr Brian Varella, CFC Utilities
Aaf`rf-e2ne A. S Bowen, P.E.
OCR Supplemental Drainage Report Page 3
CITY OF FORT COLLINS
080102
ZONE AH
(EL 49041
4
i3
ZONE AE
0
D \
Spring
= 20 P
.t� .Spring Creek a
�N ZONE AE n PROSPECT PARK LI
A
VNUALCHANCE
DD DISCHARGE
JNED IN CULVERT
9�),,
4
4>?p8
MAP SCALE 1" = 500'
50 500 00
ZONE
...0- —IGO
ET
a=
A ;
-','n�''��p'��
;�"utmlltl01W1
�YANtL
UVWH
4904
FIRM
a
m
FLOOD INSURANCE RATE MAP
LARIMER COUNTY,
r
4491000m
N
m
COLORADO
E
I � I ID
AND INCORPORATED AREAS
PAM 983 OF 1420
.d
(M MAP INDEX FOR FIRM PANEL LAYOUT)
O
DSO
CZAAMUNITY NUMBER PANEL SUFFIX
tApaERfptMly Of61
14
—ZONE AE
ramcauxe.cm or ow „
�t�
'D
EF
�FLOODING CACHE LA PO
)JECT
;ATIONpl�.
'. �" a
IaNanT 0—v �'w wpay. MunWerrcNw.w
BMrlaga0 tle oast on IIRJai%t aOWcnfwn tw fa WpCt
�
",.
mnegrcry
rxa>w MAP NUMBER
ZONE AE-
®
s 08069CO983H
4900
r MAP REVISED
�`axa "
a
as MAY 2, 2012
E
Ftderat Emergtvtey Maaagtwhent Agency
extreptea uemp FJ fT 0 LI— Ths map doee not ref act changes
or am.hcI menb which may hat! ben made subaequem to the date an the
the dock. For the latest proWtt Wormadon but Nadenal Feed Insurance
Program Rood maps chock the FEMA Flood Map St" at w mec.fom..gw
Leo -�-•_- \ T��/
i® No iNO.NKM
760 WhoWm Way. 9W9. C Sint 200
Fart Colkm Colorado
X ` .
� oar / '�•�
i
\ DRY ; .fj, ' \ ' oar
10
ply$ /3 �rFstlyy �� 9�7$• °m 9'
cepi i D O,
TWTR---'--
rIwawo
rr �v -,d ,1-"rL �,� ...
L
���_i�
---
N
SCALE: 1" = 2W
� I
� I
l
II
EXHIBIT
BFE DETERMINATION
SEVEN LAKES PUD PHASE II
AMENDED PLAN
OCR BUILDING ADDITION
DRAINAGE PLAN
SEVEN LAKES PUD PHASE II SUBDIVISION -
AMENDED SITE PLAN (OCR SITE)
LEGEND
�i
COMTKXW
A, BA910E9fN POMT
—_— maPngn aASM BDIwARr
\ � � � y r3• ` _ --�•y�--• �s::•�,�'�' .,a.� --- Exs,�D sTael srtw
fit
Il � � �/ I \ y;s..� f i e r -•��-- rLnII oExcrlw
OCR
lot, — —� _ J N BUILDING
/•.7 / 1 I t' �_ III _ 7� .L i�
`H aH!?SLILLSGLE:f.Su
_ _ — _ _ _ — _ � _ y�J G n}�� — — S �a acL— �a Aso w>,aa. M. wYw 0. mb 2DD
i vme m.2
,Ioe R Dmmla.o.W10.0
o
Fliniamr.
K:\DJp\0010\O� W \00 f O_EnMq�. Gp
N
O
W
W
0
U
w
0
d
N
0
a
E
0
U
C
.y
R
m
c
U
U
cq
CO
o
N U
o
o
o
c
m
U
a)
U
O
O
r
N
r
M
a0
CDC
tf
U
�
o
0
0
0
n
a�
N
Q
U
C
(D
cr
o
0
0
0
2
U.
U
m
'y
�n
Ln
O
N
M
O
O
co
V
Il
r
of
K)
c
E
O
O
O
O
O
O
0
U
U
`c
U
in
u]
O
�n
O
u-)
O
u)
O
O
m
m
N
O
N
O
N
m
N
O
U
O
O
O
O
O
O
O
O
O
C)
0
c
U
N
I�
O
O
V
O
O
V
O
Q
V
co
CDO
N
41
0
6
0
0
0
0
0
0
Q
au
a)
a)
a)
O
O
O
O
c/)
O
a)
o
O
o
O
o
0
>
v
>
v
>
co
v
v
a_.�
¢�.
d
N
fl
-
.
y
O
O
_
N
N
-
O
O
-
Q
y
10
Q)
cc
a7
m
m
O
W
w
m
w
a)
U)
C
m
C
m
C
m
C
m
J
J
J
J
V
R
O
V
cc
6
M
CO
M
d
r
04
o
0
0
Q
C
co
E n
w
w
0
m
r
0.
m
C
m
N
cu
m
L
a
Y
J
m
CO
c
O
N
O
E
0
_c
C
m
M
v
O C O
m E 0
cv
F I`a
p >
U p O
o F-
O It
E m
m
N
N ^
N
t6 _
U ~
al �'
C U h
Q 4
C R
N —QOi
O
U>
c
c
nu
urn
m°�
L Cn
o 0
0 0
U
a L
C v
c 3
N
L p —
U LL
0
> d
o
N ~ O
E
i=
a�
>
R > m
F. F T
m ch
co c
a o
c
d
>
N
d
� O
T
coa
mmoo
N
j Cc
t+J
17
Q y
O
O J
LL
J
j
O
C
g
n
IO
r� M
V m
UU
U
N
m
o
c
0
CO m
0 0
o m
0
C
01
N
U
o
oN
nr�m�n
coo,
c U
o o
0 0
a
Q
U
0
c Ci
n
OD
O O
O o
u`.
C
co
I
cc
0]
W
W
1
C
N
r
M
r
N
M
co
W
X
L.0
r
m
O
y
r
N
O
O
N
ON
r
Q
r
�. O
y O
Ur
N cc
y
O
= y
.
O
W
�
m
^O
U
N
N
(J
O
r
o
5 C
r
Q) r
Y
cu
LL y
M
C
O
Q
y�
r
O
N
r
p
(O
r
O
r
O
N
y
m
rn
rn
m
co
m
m
co
L O
r
C
�>
co
co
co
C
_ O
M
V
?
-Ir
mr
c
m
y
y
M
r
n(no
co
co
v
N
N
N
N
N
ca
_ O
00
F- a
C
O
(D c`
Ci
U O
C T'
O
U
O @
O T
co
E
F. N
N �
C O
O T
IO
O
V
M
U �
CO
W
Cl
(D
0 o
o r
U
o
O @
7 T
O
�rw(n
N
M
O
�
0
0
0
0
;o
� r
Q
U`
C
O
N
r
M
co
O
tf7
O
LL N
@
Q
v
C cc
M
r
(D
r
a
(`")
@
0]
of
r
N
X
Xcc
r
M
m
W
W
a
Cc O U
� U @
U Q
N O 'U C.)d
O m CB a) L
Z U CO U
N U N
N
O �
U5.jN 1 co
m I n I of
p o
m
d c N V
v Lo
N
v c I S.
� O co co
C
O M M
co
� I �
N co
a n '- co
c
O C6
U m
Pc- - I
U o d
O
nWs
Worksheet Protected
F- DESIGN PEAK FLOW FOR ONE-HALF OF STREET BY THE RATIONAL METHOD
Project: OCR
Inlet ID: existing - southern type R inlet
Design Flow - Gutter Flow * Carry-over Flow
OVERLAND $IDE OVERLAND I
FLOW l 4 STREET I 4 FLOW 4,
? 11
j —GUTTER FLOW PLUS CARRY—OVER FLOV •— f GUTTER FLOW Show Details
I'',. f T INLET -
1./2 OF STREET
(local peak flow for tit of street, plus Dow bypassing upstream subcatchments)
If you entered a value here, up the rest of this sheet and proceed to sheet
Q =1 7.2
OAllow
21.9 bets
FILL IN THIS SECTION
R-,
Geographic information: 1 Lnter am o 1 e ue cs s
FILL IN THE SECTIONS
SubatchmenI Area=
Acres
BELOW.
Percent Imparviousnesa =
°!e
-
NRCS Soil Type
JA, B, C. ar D
Site Type:
Slope (ftf t)
Length (fl)
Site Is Urban
Overland Flow =
O Site is Non -Urban
Gutter Flow =
Design Sloan Realm Period, T,
Retu-n Penod Design
Preeipilabon, Pt
C,
User -Defined Storm Runoff Coefficient (leave this blank to accept a calculated value), C = _
User -Defined Syr. Runoff Coefficient (leave this blank to accept a calculated value), Cs
Bypass (Carry -Over) Flow from upstream Subcatchments, qs cis
Total Design Peak Flow, 0 -1 7.2 1 21.8 cfs
UD-Inlet_v3 01-Design Point 1.4s, Q-Peak 2/17/2012, 12.17 PM
Wcs
11 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) 11
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Project: OCR
Inlet ID: existing -southern type R inlet
TLROWN......, .....
a�cK
is W --:{'— T. Street
I A Crown
num Allowable Width for Spread Behind Curb
Slope Behind Curb (leave blank for no conveyance credit behind curb)
ring's Roughness Behind Curb
: of Curb at Gutter Flow Line
ce from Curb Face to Street Crown
Depression
Width
Transverse Slope
Longitudinal Slope - Enter 0 for sump condition
ig's Roughness for Street Section
T_K = 16.0 ft
SaacK ` OA20 ft. vert. III hodz
neAcx = 0.020
HOURS=
i 6,00
inches
TcRovm =
58.0
ft
a =
2.00
inches
W =
2.00
ft
Sx =
0.020
ft. vert. / ft horiz
So =
0.005
ft. vert ! ft. horiz
nsTREET =1 0.016
Minor Storm Major Storm
Max. Allowable Water Spread for Minor & Major Storm Tw x = 15.2 15.2 ft
Warning 02 Max. Allowable Depth at Gutter Flow Line for Minor & Major Storm d. = 12.0 12,p inches
Allow Flow Depth at Street Crown (leave blank for no) check = yes
Minor Storm Major Storm
Max. Allowable Gutter Capacity Based on Minimum of Q, or Q. Q,Ro�' 6.1 GAcfs
WARNING: MINOR STORM max. allowable capacity is less than now given on sheet'Q-Peak'
WARNING: MAJOR STORM max. allowable capacity is less than flow given on sheet'Q•Peak'
Warning 02: Minor Storm is Overtopping the Curb.
UD-Inlet_v3 01-Design Point 1.xis, O-Allow 2/17/2012, 12:17 PM
INLET IN A SUMP OR SAG LOCATION
Project = OCR
Inlet ID • existing - southern type R Inlet
__ __..
_ W(C)
Kcurb
�. WP
Lo(G)
Warning
t of Inlet
Inlet Type
it Depression (additional to continuous gutter depression a' from'O-Allow'}
µe.,,'
fiber of Unit Inlets (Grate or Curb Opening)
No
Depth outside of Local Depression at Inlet
Flew Depth
e Information
ph of a Unit Grate
L. (G)'
h of a Unit Grate
We
Opening Ratio for a Grate (typical values 0,15-0.90)
A.
Bing Factor for a Single Grate (typical value 0.50 - 0.70)
CG (G)'
e Weir Coefficient (lypcal value 2.15 - 3.60)
C.. (G)'
e Orifice Coefficient (typical value 0,60 - 0.80)
C. (G)
f Opening Information
ith of a Unit Curb Opening
L. (C) .
ht of Vertical Curb Opening in Inches
H—
ht of Curb Orifice Threat in Inches
H— :
e of Throat (see USDCM Figure ST-5)
Theis
Width for Depression Pan (typically the gutter width of 2 feet)
W.
ging Factor for a Single Curb Opening (typical value 0, 10)
Cr (C)
Opening Weir Coefficient (typical value 2.3-36)
C., iC)'
Opening Orifice CoeKden( (typical value 0.60 - 0,70)
C. (C)
at Inlet Interception Capacity (assumes clogged condition)
Q..
tNING: Inlet Capacity less than Q Peak for Minor and Major Storms
O rcer •eauneo
Warning 3: Clogging factor is not in the recommended value for Inlet type specified.
MINOR MAJOR
CDOT Type R Curb Opening
inches
incites
feet
feet
3.00
3.00
1
1
6.0
6.0
MINOR MAJOR
NIA WA
WA
NIA
NIA
WA
WA
WA
N/A
NIA
NIA
NIA
5.00
5.00
6.00
6.00
6.00
6.00
63.40
63.40
2.00
2.00
0,10
3.60
3.50
0.67
0.67
MINOR MAJOR
est
noires
nches
legrees
not
UD-Inlet_v3 01-Dess9n Point 1 xis, Inlet In Sump 211712012, 12.17 PM
' INLET IN A SUMP OR SAG LOCATION p
proms. OCR
Itdait ID existing - northem type R inlet at Design Point 1
N-Cwb H-Vwit -
top-
Lo (o)
Warning
ion Information (Input)
o' Inlet
Inlet Type
I Depression (additional ional to conenums gutter depression's' from'O-Allow)
'7:
fiber of Unit Intel$ (Grate or Curb Opening)
No
' Depth outside of Local Depression at Inlet
Flaw Depth ;
a Inforration
Ith of a Unit Grate
4 (G)'
h of a Unit Grate
W.
Opening Ratio for a Grate (typical values 0.15-0.90)
A,ro
Bing Factor for a Single Grate (typical value 0.50 - VO)
CI (G) '
a Weir Coefficient (typical value 2.15 - 3.60)
C„ (G)'
Orifice Coefficient (typical value 0 60 - 0 60)
C, (G)'
r Opening Infovnatipn
th of a Unit Curb Opening
L. (C)'
III of Venial Curb Opening in Inches
H_
ht of Curb Orifice Throat in Inches
Hwm'
e of Throat (sae USDCM Figure ST-5)
Theta •
Width for Depression Pen (typically the gutter width of 2 feet)
W, -
Bing Factor for a Single Curb Opening (typical value 0,10)
G (C) _
Opening Weir Coefficient (typical value 2,3-3.6)
C„ (q
Opening Orifice Coefficient (typical value 0.60 - 0 70)
C. (C)'
al Inlet Interception Capacity (assumes clogged condition)
Qa
WING: Inlet Capacity less than O Peak for MAJOR Storm
O vrwcraauneo =
Warning 3: Clogging factor is not in the recommended value for inlet type specified.
MINOR MAJOR
CDOT Type R Curb Opening
3.00 3.00 inches
1 1
6.0 6.0 inches
MAJOR
WA feet
WA feel
NIA
NIA
NIA
WA
NIA
WA
WA
NIA
WA
NIA
e11Nr1R Ut 1nR
5.00
5.00
6.00
ll
6.00
6.130
63.e0
63.40
2.00
2.00
0.10
3.60
1 3.60
O.B7
0.67
MINOR MAJOR
eel
riches
,Chas
leg—s
mt
UD-Inlet_Jd 014Design Point 2xis, Inlet In Sump 2/172C12, 12-19 PM
Stvrn'1 Pi PV
Ex. 8" Pipe Calculation at DP 3
Project Description
Friction Method Manning Formula
Solve For Full Flow Capacity
Input Data
Roughness Coefficient
0.013
Channel Slope
0.02000
fUft
Normal Depth
067
ft
Diameter
0.67
ft
Discharge
1.73
ft'/s
Results
Discharge
Normal Depth
Flow Area
Wetted Perimeter
Top Width
Critical Depth
Percent Full
Critical Slope
Velocity
Velocity Head
Specific Energy
Froude Number
Maximum Discharge
Discharge Full
Slope Full
Flow Type
GVF Input Data
Downstream Depth
Length
Number Of Steps
GVF Output Data
Upstream Depth
Profile Description
Profile Headloss
Average End Depth Over Rise
Normal Depth Over Rise
SubCritical
1.73 Wis
0.67 ft
0.35 ft'
2.10 ft
0.00 ft
0.60 ft
100.0 %
0.01759 ft/ft
4.91 ft/s
0.37 ft
1.04 ft
0.00
1.86 ft3/s
1.73 ft'/s
0.02000 Wit
0.00 ft
0.00 ft
0
0.00 ft
0.00 ft
0.00 %
100.00 %
Bentley Systems, Inc. Haestad Methods Solution Center Bentley FlowMaster 108.01.071.00]
2/17/2012 12:12:53 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 2
Rain 64r0►1
Designer:
Company
Date:
Project
Location:
HEM
TST
February 16, 2012
OCR
Design Procedure Form: Rain Garden (RG)
Sheet 1 of 2
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, I,
I, =
100.0 %
(100 % if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio It = 1,1100)
i =
1 000
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time
WQCV =
040 watershed inches
(WQCV= 0.8' (0.91- i'- 1.19 - i', 0.78 -i)
D) Contributing Watershed Area (including rain garden area)
Area =
21,000 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume
V_" =
700 cu ;0
Vol = (WQCV 1 12)' Area
fv7
F) For Watersheds Outside of the Denver Region, Depth of
ds =
in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region,
VWaCV OniER =
00 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume
VWQCy USER =
cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum)
D•wocv =
12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical)
Z =
3.00 It 1 ft Z < 4:1
(Use "Cr if rain garden has vertical walls)
C) Mimimum Flat Surface Area
A_ =
467 sq ft
D) Actual Flat Surface Area
Aka„ =
903 sq ft
E) Area at Design Depth (Top Surface Area)
A,00 =
1613 sq ft /
F) Rain Garden Total Volume
V,-
f1258 cu ftl f f r
(V,= ((A,.+ A._) ! 2) 'Depth)
3. Growing Media
Choose One —
* 18" Rain Garden Growing Mecla
O Other (Explain):
4. Underdrain System
A) Are underdrains provided?
Choose One
O YES
* NO
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage
y =
N!A ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours
V0112=
N/A cu ft
iii) Orifice Diameter, 3/8" Minimum
Do =
N/A in
Copy of JD-13MP_v3_01.xIs, RG 2/1612012, 4:37 PM
UVeir
Project Description
Solve For
Input Data
Headwater Elevation
Crest Elevation
Tailwater Elevation
Crest Surface Type
Crest Breadth
Crest Length
Results
Discharge
Headwater Height Above Crest
Tailwater Height Above Crest
Weir Coefficient
Submergence Factor
Adjusted Weir Coefficient
Flow Area
Velocity
Wetted Perimeter
Top Width
Weir Calculation at DP 2
Discharge
Gravel
4900 75 ft
4900.25 ft
4899.36 ft
300 ft
5.00 ft
5.22 ft'/s
0,50 ft
-0.89 ft
2.96 US
1.00
2.96 US
2.50 ft'
2.09 Ws
6.00 ft
5.00 ft
0-1oo=111 CFS
Bentley Systems, Inc, Haestad Methods Solution Center Bentley FlowMaster [08.01.071.00]
2117/2012 12:15:24 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1
Project Description
Friction Method
Solve For
Input Data
Roughness Coefficient
Channel Slope
Left Side Slope
Right Side Slope
Bottom Width
Discharge
Results
Normal Depth
Flow Area
Wetted Perimeter
Top Width
Critical Depth
Critical Slope
Velocity
Velocity Head
Specific Energy
Froude Number
Flow Type
GVF Input Data
Upstream Depth
Length
Number Of Steps
GVF Output Data
Downstream Depth
Profile Description
Profile Headloss
Downstream Velocity
Upstream Velocity
Normal Depth
Critical Depth
Channel Slope
Critical Slope
2/16/2012 4:42:31 PM
Chanrwj
Channel A -A Calculation
Manning Formula
Normal Depth
Supercritical
0.060
0,90000
ft/ft
4.00
ft/ft (H:V)
4.00
ft/ft (H:V)
8.00
ft
28.10
ft3/s
nog(
2.86 f12
10.55 ft
10.47 ft
0.65
j
ft
0.06626 ft/ft
p rc_<.
9.83 ft/s
1.50 ft
1.81 ft
3.32
0.00 ft
0.00 ft
0
0.00 ft
0.00 ft
Infinity f /s
Infinity f /S
0.31 ft
0.65 ft
0.90000 ft/ft
0.06626 ft./ft
6l 4J
Bentley Systems, Inc. Haestad Methods Solution Center Bentley FlowMaster [08.01.071.00)
27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 11 of 1
SUBJECT—SCYEIIL���L:.S_Gft��J...1G__>?:.
/ff/ _SJac m_I2Ga 4c-=S1s L1=3J LsU_ SHE +o.—----- -
--_------_ PROJECT
B ..T ARGA= b•33 Ao G= 085 I
.��IIII.Ii i' I
i I TC.=IJ'����1!'(-D•$S)/OSO� = LoM/N.
I
I I. �D4w Li.;ayR' 0• BS x b 8,0 X 6•'S3 9.7 c.,x,
1
U•b5x 3.2 X
DeV: Q.lo,yr I.25xa$Sx 5•Lx C.•C.Fs.
iL
J.g7(lJ'a•is)rao
i
QLy,2= 0,4SA L,3x /./0 = /•/4- c.•-,.7
DEvI. Q�YayR.' U,4Sxb•IX A/4 Z,03..c.r,.
Dc-v`• Q ro-0y,e J•25x0.43xE,7x r./0.-
JASI,', AeEA- 0.4L Ac. c<0.a0
To= J•87(1.1-0,3)seD/� i'SnM1l,,J.
0.6
QlbyQ0,30 xZ. ESxP94
Dcv. QioPw' l•LJ XO.3DxlG", c= 0,7Ic.F:f.
SUBJECT CATE -Jf/'
!!V v`-Laa ��e_ev tocct[cgrLas s. NO-2------ --_------ — ---. PROJECT NO. ---------
-
t
Sx0rs'rl &!-DEVEt_OPEE, .'EVSAt LAA-EJ (OF'S"c)
'Ai E.E 13'S1A.0 rs ZoN%N(y - S P G'O•g1
• I i I..I I'j`-:d67�11.1
'Dc+; Qzyc.= 0. SS 2.1 x g.s /S•/7 G•/r I.
IacJ IQio yq °' 0• BS x3.7s x 9,5 C7.01 c.i'.r
IGO YK _ 1'4J + 0•SSx �„O 7 B.S 3.35 [. FS.
i .
i
t IS ,EVEAJ .C.AkE.i'PN Aff: 2Z iCN SIrF�
I. •I inP •1 A2.e;A. -i 3.35 AcC.= 0.85
i
Tz
O..g3 c nr
Fs'r. Z•dx 3 3s - C
i
t biv �..Q loy,C' D•PJX 6. 2."•:�. jl -. r'S.
t.
�DE: V, �lX /GO ye- 'L 3.°s S.
I
I
7,\L_
TYP16A6 OrTa 4K055 6961109
LERM
April 5, 2012 01D
EARTH ENGINEERING
CONSULTANTS, INC.
Gateway Medical Services
c/o Mr. Michael Bergerson
2500 East Prospect Road
Fort Collins, Colorado 80525
Attn: Mr. Michael Bergerson (mber eg_ rson(aOrthohealth.com)
Re: Subsurface Exploration — Addendum Report
Proposed Rain Garden Concept Adjacent to Pavement Area Improvements
Orthopaedic Center of the Rockies
2500 East Prospect Road
Fort Collins, Colorado
EEC Project No. 1122002
Mr. Bergerson:
Enclosed, herewith, are the results of the supplemental subsurface exploration/soil
percolation evaluation completed by Earth Engineering Consultants, Inc. (EEC)
personnel for the rain garden concept planned along the north side of the proposed on -site
pavement improvement area, (please refer to the enclosed site diagrams) at the
Orthopaedic Center of Rockies (OCR) facility at 2500 East Prospect Road in Fort
Collins, Colorado. For this phase of the project three (3) soil percolation borings were
located and drilled within the proposed rain garden concept as shown on the enclosed site
diagram, created from civil drawings provided to us by TST, Inc. — Consulting Engineers.
This supplemental study was completed in general accordance with our electronic
proposal dated March 27, 2012.
EXPLORATION AND TESTING PROCEDURES
The supplemental rain garden/soil percolation borings were located in the field by
representatives of Earth Engineering Consultants, Inc. (EEC) by pacing and/or estimating
locations relative to identifiable site features. The approximate boring locations are
indicated on the attached boring location diagram. The locations of the borings should be
considered accurate only to the degree implied by the methods used to make the field
measurements.
4396 GREENFIELD DRIVE
WINDSOR, COLORADO 80550
(970) 545-3908 FAX (970) 663-0282
www.earth-engineering.com
Earth Engineering Consultants, Inc.
EEC Project No. 1122002
April 5, 2012
Page 2
The borings were completed using a truck mounted, CME-45 drill rig equipped with a
hydraulic head employed in drilling and sampling operations. For this study, as shown
on the enclosed site diagram, soil percolation borings P-1 and P-3 were extended to
depths of approximately 5-feet below existing site grades, while soil percolation boring
P-2 was extended to a depth of approximately 8-feet below site grades. Upon completion
of the drilling operations, the borings were filled with water, saturated for an approximate
24-hours period and in -situ infiltration/soil percolation characteristics were performed the
following day at each boring location.
SUBSURFACE CONDITIONS
In summary, a sparse vegetated/topsoil layer was encountered at the surface of each soil
percolation boring and was underlain by a zone of cohesive sandy lean clay subsoils,
which was either fill of native overburden material. The cohesive zone extended to the
native granular subsoils below, which were encountered at an approximate depth of 4-
feet below existing site grades. The native granular fine to course silty sand with gravel
and intermittent cobbles extended to the depths explored in the soil percolation borings,
approximately 5 to 8-feet below site grades. Groundwater was encountered within the
deeper profile boring P-2 at an approximate depth of 5-feet below site grades during the
initial drilling operations. The subsurface conditions encountered within the rain
garden/soil percolation borings were very similar/consistent with those described in our
"Subsurface Exploration Report" completed for the site on January 17, 2012, EEC
Project No. 1122002.
ANALYSIS AND RECOMMENDATIONS
We understand a rain garden concept is planned along the north side of the proposed on -
site improvement parking area as shown herein as part of the storm water run-
off/drainage plan. Based on our review of the rain garden design concepts prepared by
TST, Inc. - Consulting Engineers, the existing grade in the general vicinity of the
proposed rain garden is between approximate elevations 4900 to 4902. The bottom of the
proposed rain garden, as shown herein will be at an approximate elevation of 4899.25. It
appears as part of the rain garden concept the upper 18-inches will consist of a sand/peat
Earth Engineering Consultants, Inc.
EEC Project No. 1122002
April 5, 2012
Page 3
mixture of approximately 25% ASTM C33 concrete sand and approximately 75% peat
mix. We also understand the current rain garden concept does not have an underdrain
system or outlet structure designed. In essence the proposed rain garden concept as
currently planned is a simple rain garden that will infiltrate into the underlying subsoils
with no underdrain system and will have an overflow weir without an outlet structure.
The review comments from the City of Fort Collins' Stormwater Department indicated
the following: "The City requires underdrains and the standard urban drainage outlet
structure for rain gardens/bioretention ponds. If soil sampling shows A or B soils and a
high percolation rate, underdrains can be omitted from the design. "
For this project, we conducted a series of three (3) soil percolation tests at approximate
depths of near surface grades to about 4-feet below grades at boring locations P-1 and P-
3, and from about 3-feet to about 8-fet below site grades at the boring P-2 locations.
Again, based on our review of the rain garden concepts it appears the majority of
cohesive materials would be removed to establish the design grades, which would also
include the upper 18-inches being replaced with a sand/peat mixture.
Soil percolation testing within the proposed location of the rain garden, conducted for a
period of approximately 70 minutes after an initial "24-hour soaking period", is
summarized below, and a spreadsheet is also included with this report.
Percolation Test Results
Test Hole
Depth (feet)
Soil Classification
Percolation Rate
(minutes/inch)
P-1
4
Sandy Lean Clay transitioning toward Sand with Gravel
16
P-2
8
Silty Sand with Gravel
4
P-2
4
Sandy Lean Clay transitioning toward Sand with Gravel
22
Based on the soil percolation rates presented herein for the underlying fine to course
granular subsoils, (i.e., in essence less than 5 minutes per inch), the relatively shallow
depth to the groundwater table in this area, which is approximately 5-feet below site
grades, and the understanding that the majority of the upper cohesive subsoils will be
Earth Engineering Consultants, Inc.
EEC Project No. 1122002
April 5, 2012
Page 4
removed, it is our opinion an underdrain system along with an outlet structure would not
be necessary for the proposed rain garden planned as part of the site improvements at the
referenced site.
We appreciate the opportunity to be of service to you on this project. If you have any
questions concerning this report, or if we can be of further service to you in any other
way, please do not hesitate to contact us.
Very truly yours,
onsultants, Inc.
David A. Richer, P.E.
Senior Geotechnical Engineer
cc: Wm. T. Welch LLC — Mr. Will Welch: wwelch(d�wmtwelch.com
TST, Inc. — Ms. Sharlene Shadowen, P.E.:sshadowen(&tstinc.com
The Neenan Company - Mr. Bill Pigg: bill.pigg(&neenan.com
Mr. Jake Coutts iake.coutts(a)neenan.com
Mr. Bob Mooney: bob. mooney(a,,neenan.com
-- - --- ------
-
----
-----------
---- --- ---
_
�a`
�
L
E
i \l; `` OIIAbINO bal111�G ..
•�-
\,•ems+'..ibtGYiY
""
�'�
...
� �
FLOODWA
TO 1161AW
iYYC11T k1
NxfCH
it,
I T_
PAVING
W
L.7-
TEE 4' ROOr DRAINr��xlsr e' vnc
E msi.
- --�.e MATCH
ATCH
..... .� -n., - ANCUY ! M,1 F Ex157MK GTRF
TO RQFARO
-- - �..r' '� �UND
AS NECESSAPY
T:
1
Legend I
Approximate-----
-
Locations for 3 Soil
Percolation Borings------------------ -------
Boring-Location Diagram
Orthopaedic Center of the Rockies - Proposed Addition
Fort Collins, Colorado
North EEC Project #: 1 122002 Date: March 2012
NM to Scale
EARTH ENGINEERING CONSULTANTS, Ir`
(�(� BOTTOM OF POND 4899.25 —
VERTICAL CURB
& GUTTER
2' CURB —
OPENING
PAVEMENT
IN
TRANSITION INTO A V—SHAPED
CONCRETE RUNDOWN INTO A
SECTION AT BOTTOM THAT HAS
3—INCH RIVER ROCK INBEDDED
1.5—INCHES INTO THE
CONCRETE.
CONCRETE PAN
A
POND WATER SURFACE
4900.25
OVERFLOW WIER
/ --TURF REINFORCEMENT MAT -
- — — — — f� PROPEX GEOSYNTHETICS
LANDLOK 450 OR EQUAL.
24" CURB CUT TO BE INSTALLED PER
W/ V—SHAPED VERTICAL CURB MANUFACTURER'S
CONCRETE & GUTTER SPECIFICATIONS.
RUNDOWN
ELEV. 4899.75
PLAN VIEW
DRYLAND GRASSES AND
WILD FLOWERS SEEDED
IN ACCORDANCE WITH
SECT. 5.6 OF VOL. 3.
DO NOT USE SOD.
REFER TO LANDSCAPE
PLAN FOR PLANTINGS
& LANDSCAPING
B
18" SAND/PEAT LAYER
f1.5—ft 25% ASTM C-33 SAND
75% PEAT MIX
ALL SIDE SLOPES 2:1 OR FLATTER
WRAP ALL GEOTEXTILE
FABRIC AND IMPERMEABLE
LINERS TO TOP OF SOIL.
ATTACH ALL LINERS FIRMLY
TO WALLS OR TRENCH
SIDES.
OVERFLOW
WIER
Woven geotextile fabric meeting:
ASTM D4751—AOS US Std. Sieve #50 to #70,
ASTM D4633 min. trapezoidal tear strength 100 x 60 Ibs,
Minimum COE specified open area of 4%.
SECTION A -A
Orthopaedic Center of The Rockies - 2500 East Prospect Road - Fort Collins, Colorado
EEC Project No. 1122002
Soil Boring
No.
Depth of
Boring, Ft.
Zone of Soil Percolation,
Range in Ft.
Time
Difference in Time,
Minutes
Inches
Measured
Difference in Inches between
readings, Minutes
Soil Percolation Rate,
Minutes/Inch
P-1
3.5
0.0 - 5.0
0:00
17.375
---
---
0:10
10
18.375
1
10.00
0:20
10
19.125
0.75
13.33
0:30
10
19.75
1 0.625
16.00
0:40
10
20.375
0.625
16.00
0:50
10
21.0625
0.6875
14.55
1:00
10
21.5
0.4375
22.86
1:10
10
22
0.5
20.00
Average Soil Percolation Rate minutes/inch
16.11
P-2
10
3.0 - 8.0
0:01
---
34.625
---
---
0:11
10
47.5
12.875
0.78
0:21
10
50.25
2.75
3.64
0:31
10
51
0.75
13.33
Refill
30.75
0:41
10
44
13.25
0.75
0:51
10
49.75
5.75
1.74
1:01
10
51
7
1.43
1:11
10
52.5
1.5
6.67
Average Soil Percolation Rate minutes/inch
4.05
P-3
3.5
0.0 - 5.0
0:02
---
26.625
---
---
0:12
10
27.25
0.625
16.00
0:22
10
27.75
0.5
20.00
0:32
10
28.25
0.5
20.00
0:42
10
28.75
0.5
20.00
0:52
10
29.125
0.375
26.67
1:02
10
29.5
0.375
26.67
HE
10
29.875
0.375
26.67
Average Soil Percolation Rate minutes/inch
22.29
SEC
-- �' 1 ---' — _ --- =------ i - -----
- 1 �
Vurking
Pddipan
3r Spaces—lf
1 1
—t 1 • �---i
I
B-1 Bklp AddlMW
/
10.640 SF
B-6
01
/ , B-3$
I �
r
—
—1 I
air
t IV I •IOr � i
Legend I
$ B-1
-- -- - -
/ ---_ —
t I II
thru B-4: Approximate
Locations for 4 Foundation---------
Related Borings
-t- - ------------- - ---
-0 B-5 & B-6 Approximate
Locations for 2 Pavement
Related Borings
Proposed Boring Location Diagram
Orthopaedic Center of the Rockies
Fort Collins, Colorado
North
Not to Scale
Date: December 201 1
EARTH ENGINEERING CONSULTANTS, INC.
ORTHOPAEDIC CENTER OF THE ROCKIES EXPANSION
FORT COLLINS, COLORADO
PROJECT NO: 1122002 DATE: JANUARY2012
LOG OF BORING B-5
RIG TYPE: CME45
SHEET 1 OF 1
WATER DEPTH
FOREMAN: DG
START DATE
1/12/2012
WHILE DRILLING
7.0'
AUGER TYPE: 4" CFA
FINISH DATE
1/1212012
AFTER DRILLING
N/A
SPT HAMMER: MANUAL
SURFACE ELEV
N/A
24 HOUR
N/A
SOIL DESCRIPTION
D
N
OU
MC
DD
A -LIMITS
-200
SWELL
I LL
PI
PRESSURE
% @ 500 PSF
TYPE
(FEET)
(BLOWS/FT)
(PSF)
(%)
(PCF)
(%,)
APPARENT FILL MATERIAL:
1
Sandy Lean Clay (CL) / Clayey Sand (SC)
dark brown, moist, varying amounts of gravel
2
medium stiff
FCS
% @'150 psf
27
9000+
12.4
1 122.6
4000 psf
4.8
3
4
SS
5
6
22
--
13.4
SILTY SAND with GRAVEL (SM-SW
brown, gray
moist to wet,
7
medium dense to dense
8
'intermittent COBBLES with increased depth
9
Ess
10
-
11
-
34
13.1
BOTTOM OF BORING DEPTH 10.5'
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Earth Engineering Consultants
ORTHOPAEDIC CENTER OF THE ROCKIES EXPANSION
FORT COLLINS, COLORADO
PROJECT NO: 1122002 DATE: JANUARY 2012
LOG OF BORING B-6
RIG TYPE: CME46
SHEET 1 OF 1
WATER DEPTH
FOREMAN: DG
START DATE
1/12/2012
WHILE DRILLING
6.5'
AUGER TYPE: 4" CFA
FINISH DATE
111212012
AFTER DRILLING
NIA
SPT HAMMER: MANUAL
SURFACE ELEV
N/A
24 HOUR
NIA
SOIL DESCRIPTION
D
M
ou
MC
DII
A-LIMITS
-200
SWELL
LL
PI
PRESSURE
Y @ 500 PSF
TYPE
(FEET)
(BLOWSIFT)
(PSF)
(%)
fPCF)
I%)
APPARENT FILL MATERIAL.
1
Sandy Lean Clay (CL) / Clayey Sand (SC)
_
dark brown, moist, varying amounts of gravel
2
medium stiff
11,
50
--
8.9
132.0
1100
1.5
3
4
SS
5
6
12
4000
27.6
SILTY SAND with GRAVEL (SM-SW)
brown, gray
moist to wet.
7
medium dense to dense
8
9
FF-S
10
11
10
--
14.1
BOTTOM OF BORING DEPTH 10.5'
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Earth Engineering Consultants