HomeMy WebLinkAbout20131437.tiffPhase II Drainage Amendment Memo
PATRICK
ENGINEERING
Pawnee Water Management
Groundwater Load �ut &
Recycling Facility
Weld County. CO
I it
Prepared for
Halliburton
1125 17th Street, Suite 1900
Denver, CO 80202
Patrick Project Number
21273.003
Date Prepared: May 2011
Revised: February 2012
Amended: November 2012
Partnering to Build Better Infrastructure
1400 West 122°d Avenue Suite 102 Westminster Co. 80234 : info,* patricken inecrin;.1.com : www.patrickengineering.com
PHASE II DRAINAGE AMENDMENT MEMO
WELD COUNTY, CO
PAWNEE WATER MANAGEMENT
GROUNDWATER LOAD OUT & RECYCLING FACILITY
USE BY SPECIAL REVIEW USR-1787
PREPARED FOR: Halliburton
1125 17th Street, Suite 1900
Denver, CO 80202
PREPARED BY:
Patrick Engineering Inc.
1400 West 122nd Avenue Suite 102
Westminster, Co. 80234
DATE: May 6, 2011
REVISED: February 27, 2012
AMENDED: November, 2012
Pawnee Water Management USR-1787 — Major Amendment Phase II Drainage Amendment Memo
TABLE OF CONTENTS
Page
1.0 BACKGROUND INFORMATION 1
2.0 DRAINAGE FACILITY DESIGN 2
Direct Discharge Area
Updated Water Quality Pond & Contributing Area for Phase I Sub -basin D -1A
Water Quality Swale & Contributing Area for Phase II Sub -basin 0-1B
Maintenance
LIST OF TABLES
Table 1 — Updated D -1A Water Quality Capture Volume
Table 2 — D-1 B Water Quality Capture Volume
APPENDICES
Appendix A Drainage Calculations
LIST OF FIGURES
Figure 1 Phase II Developed Drainage Plan
REFERENCES
1) "Weld County Storm Drainage Criteria Addendum to the Urban Storm Drainage Criteria Manuals Volumes 1, 2,
and 3", by Weld County Public Works Department, October 2006.
2) Weld County Code, Section 24-7-120
3) Web Soil Survey 2.0, National Cooperative Soil Survey, Weld County, Colorado, Southern Part
United States Department of Agriculture, Natural Resources Conservation Service
http://websoilsurvev.nrcs.usda.dov
4) Urban Storm Drainage Criteria Manual, Volumes 1, 2. and 3
Urban Drainage and Flood Control District
Patrick Engineering Inc.
November 2012
Pawnee Water Management USR-1787 — Major Amendment Phase II Drainage Amendment Memo
1.0 BACKGROUND INFORMATION
Pawnee Water Management has submitted a major amendment to the Use by Special Review (USR) permit #1787
to the Weld County Department of Planning Services to construct and operate a process water recycling facility
directly adjacent to the Phase I Water Load Out Facility. The intent of the recycling facility is to allow for water
recovered from oil and gas processes to be treated and reused. In addition, the facility will provide an injection well
for disposal of treated water.
This Drainage Amendment Memo provides Phase II drainage design information and is intended to amend the
Phase I Drainage Design that was approved by Weld County Public Works Department in early spring of 2012.
Design requirements suggested by Weld County for the Phase I facility were implemented in a similar method in the
separate Phase II design.
2.0 DRAINAGE FACILITY DESIGN
The drainage plan developed for the entire water load out and treatment facility is divided into four sub -basins. Sub -
basin D -1A includes Phase I construction of the Water Load Out Facility, D-1 B consists of Phase II development of
the Recycling Facility, D -1C includes the secondary containment portion of the recycling facility, and H -1A
incorporates the remaining undeveloped parcel. Both phases of construction have a separate Water Quality feature
to temporarily detain and treat stormwater runoff from that portion of the facility. Sub -basin H -1A, which comprises
almost entirely of undeveloped native grassland is allowed to continue to sheet flow from the site as in its historic
condition. (Please refer to Figure 3 Developed Drainage Plan).
Direct Discharge Area
Sub -basin H -1A covers 67.4 acres and is the remaining portion of the historical H-1 basin. 99% of this sub -basin is
the historical undeveloped grasslands that will continue to flow undetained from the site via the historical drainage
pattern. A portion of basin H -1A contains a small amount of aggregate drive surface from Phase 1 work and grassed
fill slopes that are unable to drain towards the water quality pond and will be released along with the rest of the
basin. Since this amount of aggregate surface is approximately 1% of the basin, the flows are not anticipated to
affect the overall stormwater quality or rates leaving the site.
Two grassed diversion swales to the north and south of the site will divert surface water around the site. The shallow
grassed swale to the north of the site is to be extended to the east about 460 linear feet to account for regrading of
the additional truck parking and storage area. This diversion swale continues to be routed through a 12" HDPE
culvert under the as -built access drive and daylights to existing ground on the south side of the drive. The diversion
swale proposed to the east and south of the site will divert water towards the existing shallow swale near County
Road 95. The proposed trapezoidal swales have a minimum depth of 1 -ft and a bottom width of 2 -ft (northern swale)
and 4 -ft (southern swale) in order to contain and appropriately convey any flows that collect from above the site.
Updated Water Quality Pond & Contributing Area for Phase I Sub -basin D -1A
The existing load out facility, delineated by Sub -basin D -1A, consists of an existing 3.29 acres of aggregate
pavement, 0.52 acres of concrete for truck loading and 3.56 acres of native grassed area. These areas all drain,
overland, into the Phase I Water Quality pond located at the center of the facility.
Patrick Engineering Inc.
1 November 2012
Pawnee Water Management USR-1787 — Major Amendment Phase II Drainage Amendment Memo
1.0 BACKGROUND INFORMATION
Pawnee Water Management has submitted a major amendment to the Use by Special Review (USR) permit #1787
to the Weld County Department of Planning Services to construct and operate a process water recycling facility
directly adjacent to the Phase I Water Load Out Facility. The intent of the recycling facility is to allow for water
recovered from oil and gas processes to be treated and reused. In addition, the facility will provide an injection well
for disposal of treated water.
This Drainage Amendment Memo provides Phase II drainage design information and is intended to amend the
Phase I Drainage Design that was approved by Weld County Public Works Department in early spring of 2012.
Design requirements suggested by Weld County for the Phase I facility were implemented in a similar method in the
separate Phase II design.
2.0 DRAINAGE FACILITY DESIGN
The drainage plan developed for the entire water load out and treatment facility is divided into four sub -basins. Sub -
basin D -1A includes Phase I construction of the Water Load Out Facility, D-1 B consists of Phase II development of
the Recycling Facility, D -1C includes the secondary containment portion of the recycling facility, and H -1A
incorporates the remaining undeveloped parcel. Both phases of construction have a separate Water Quality feature
to temporarily detain and treat stormwater runoff from that portion of the facility. Sub -basin H -1A, which comprises
almost entirely of undeveloped native grassland is allowed to continue to sheet flow from the site as in its historic
condition. (Please refer to Figure 3 Developed Drainage Plan).
Direct Discharge Area
Sub -basin H -1A covers 67.4 acres and is the remaining portion of the historical H-1 basin. 99% of this sub -basin is
the historical undeveloped grasslands that will continue to flow undetained from the site via the historical drainage
pattern. A portion of basin H -1A contains a small amount of aggregate drive surface from Phase 1 work and grassed
fill slopes that are unable to drain towards the water quality pond and will be released along with the rest of the
basin. Since this amount of aggregate surface is approximately 1% of the basin, the flows are not anticipated to
affect the overall stormwater quality or rates leaving the site.
Two grassed diversion swales to the north and south of the site will divert surface water around the site. The shallow
grassed swale to the north of the site is to be extended to the east about 460 linear feet to account for regrading of
the additional truck parking and storage area. This diversion swale continues to be routed through a 12" HDPE
culvert under the as -built access drive and daylights to existing ground on the south side of the drive. The diversion
swale proposed to the east and south of the site will divert water towards the existing shallow swale near County
Road 95. The proposed trapezoidal swales have a minimum depth of 1 -ft and a bottom width of 2 -ft (northern swale)
and 4 -ft (southern swale) in order to contain and appropriately convey any flows that collect from above the site.
Updated Water Quality Pond & Contributing Area for Phase I Sub -basin D -1A
The existing load out facility, delineated by Sub -basin D -1A, consists of an existing 3.29 acres of aggregate
pavement, 0.52 acres of concrete for truck loading and 3.56 acres of native grassed area. These areas all drain,
overland, into the Phase I Water Quality pond located at the center of the facility.
Patrick Engineering Inc.
1 November 2012
Pawnee Water Management USR-1787 — Major Amendment Phase II Drainage Amendment Memo
Due to site grading, the construction of Phase II, as well as additional truck parking and a screened storage area,
another 0.658 acres of aggregate pavement must be added to sub -basin D-1 A. Recalculation of the Water Quality
Pond Volumes indicates that the additional aggregate surfaces contributing to the pond will raise the Water Quality
surface elevation by only 0.04 ft. This amount is considered insignificant and there shall be no changes required to
the approved and as -built Phase I structures.
The updated information for the as -built water quality pond is in Table 1. The existing pond contains 2,900 cubic feet
of sedimentation storage and 16,500 cubic feet of Water Quality Volume.
Table 1 — D -1A Water Quality Capture Volume:
Area
(Acres)
Average
Impervious
(%)
WQCV Depth
(in)
Required WQCV
(Cu. Ft.)
WQ Elev
(ft)
Phase I Design
8.962
28
0.13
5146
5047.16
Final Design
9.621
29.2
0.13
5620
5047.20
24 -hr drain time: WQCV = 0.9*(0.91 i3 —1.19i2+0.781)
Release of the WQCV will occur in a period of 24 hours via a 2 3/4 inch diameter orifice over a 4 inch diameter pipe.
The 4 inch pipe was selected to provide a rigid outlet through the outlet works.
A trickle channel made up with high evaporative grasses is used to channel low flows into the outlet works.
Water Quality Swale & Contributing Area for Phase II Sub -basin D -1B
The proposed 4.1± acre Phase II recycling and storage facility, delineated by Sub -Basin D-1 B, contains two drainage
areas.
The first drainage area is 1.77 acres and contains 1.48 acres of gravel drive aisles and 0.29 acres of grassed fill
slopes around the facility. Stormwater from the gravel surfaces will sheet flow towards the southwest corner of the
site, to be collected in two 4 foot wide vegetated collection swales. These swales will convey the stormwater to a 4
foot wide, 1 foot deep, 1,200 cubic foot water quality swale located at the southwest edge of the facility for temporary
storage and treatment. The outlet shall be a 3 foot wide broad -crested concrete weir that will allow treated
stormwater to be released over a 24 -hour period. Any excess storm runoff greater than the design WQCV will also be
released by the weir outlet structure, which has been designed to discharge larger flows if necessary.
The second drainage area is 1.94 acres and consists of a self-contained area located in the center of the sub -basin.
This area includes the 1.74 acre contained area which surrounds the wastewater recycling equipment and storage
tanks as well as 0.20 acres of concrete pads for truck loading and unloading that drain into the containment area to
collect hose water and any other spill falling on the concrete. Storm water that also falls on these areas will be
collected by shallow diversion swales and 4" HDPE drain pipes, then either pumped through the recycling facility for
treatment internally or pumped directly into the injection well for disposal.
The proposed water quality swale contains 1200 cubic feet of Water Quality Volume. The Water Quality Capture
Volume (WQCV) was calculated per Table 2.
Table 2 — D-1 B Water Quality Capture Volume:
Area
(Acres)
Average Impervious
(%)
WQCV Depth
(in)
Required WQCV
(Cu. Ft.)
1.77
34
0.15
1128
Patrick Engineering Inc.
2
November 2012
Pawnee Water Management USR-1787 — Major Amendment Phase II Drainage Amendment Memo
24 -hr drain time: WQCV = 0.9*(0.91 i3—1.19i2+0.78i)
Release of the WQCV will occur in a period of 24 hours via a rip rap protection 3ft wide concrete weir located at the
south west corner (center) of the water quality swale. This weir will also be designed to release any storm runoff
greater than the WQCV design storm.
Maintenance
All areas of the 12.5± acre developed site are accessible for maintenance. Maintenance on the recycling systems
and pumps for the water treatment and internal stormwater collection will be periodically checked by full-time staff.
The Phase II water quality swale and outlet weir shall be inspected periodically for erosion rills and sediment build-up
in the riprap. The perimeter swales will also require occasional maintenance and inspections.
The drainage facilities for this site have been designed in the full knowledge that Weld County will not be responsible
for the maintenance of drainage -related facilities. All drainage facilities are the solely the responsibility of the owner.
Patrick Engineering Inc.
3 November 2012
APPENDIX A
Drainage Calculations
PATRICK
ENGINEERING
JOB NO. 21273.003 DATE 11/9/2012
PROJECT Pawnee Water Management - Wastewater Recycling Facility
REVISION DATE
Runoff Coefficients - Developed
Weighted Coefficients
(Type "B" Soil)
BASIN
LAND USE
PHASE I
AREA (ac.)
PHASE II
AREA (ac.)
C2
O5
O10
C100
I(%)
H -1A
Natural Grasses
70.894
66.531
0.00
0.08 '
0.17
0.36
2
Gravel Road
0.871
0.871
0.23
0.30
0.36
0.50
40
Total Area
71.765
67.402
Composite
0.00
0.08
0.17
0.36
2.5
BASIN
LAND USE
PHASE I
AREA ac.
PHASE II
AREA ac.
C2
O5
O10
C100
I(%)
D -1A
Gravel Road
4.882
5.54
0.23
0.30
0.36
0.50
40
Natural Grasses
3.557
3.56
0.00
0.08
0.17
0.36
2
Concrete
0.523
0.52
0.89
0.90
0.92
0.96
100
Total Area
8.962
9.621
Composite
0.18
0.25
0.32
0.47
29.2
BASIN
LAND USE
PHASE I
AREA (ac.)
PHASE II
AREA (ac.) .
C2
. C5
O10
C100
l(%)
D-1 B
Total Area
Natural Grasses
-
0.291
0.00
0.08
0.17
0.36
2
Gravel Road
-
1.477
0.23
0.30
0.36
0.50
40
1.769
Composite
0.19
0.26
0.33
0.47
33.7
BASIN
LAND USE
PHASE I
AREA (ac.)
PHASE II
AREA (ac.)
C2
C5
O10
C100
I(%)
D-1 C
Concrete
-
0.199
0.890
0.900
0.920
0.960
100
Containment Area
-
1.736
0.890
0.900
0.920
0.960
100
Total Area
-
1.936
Composite
0.89
0.90
0.92
0.96
100.0
Basin
D-1 A
Water Quality Capture Volume
AREA AVE IMP. WQCV WQCV 10-YR 100-YR
(ACRES) (°/0) (Inches) (C.F.) (C.F.) (C.F.)
9.62 29% 0.13 5620.2 14,256 28,846
AREA AVE IMP.
Basin (ACRES) (%)
D-1 B
WQCV WQCV
(Inches) (C.F.)
1.77 34% 0.15 1127.8
24 -hr drain time: WQCV = 0.9`(0.91 i3 -1.19i2+0.781)
C3
PATRICK
ENGINEERING
JOB NO. 21273.003 DATE 11/9/2012
PROJECT Pawnee Water Management - Wastewater Recycling Facility
REVISION DATE
WATER QUALITY VOLUME PROVIDED
WATER QUALITY SWALE LPHASE II)
STAGE CUM. WQCV
CONTOUR AREA VOLUME VOL. ELEV.
5047.0 0 0
1220 5047.92
5048.0 2440 1220
*Storage Volume calculated using the the average -end area formula:
V1,2 = [(A, +A2)/2jd
MINOR WEIR
WQ VoI= 1,127.8
10-yr VoI= 0
100-yr Vol= 0
WQ W.S.= 5047.92
*10-yr W.S.=
100-yr W.S. =
Q(wiER) = C(L-0.1 iH))H^3/2
Q(w1ER) = C(L-0.1 iH))H"3/2
= 0.43 cfs
C = 3.330
L = 3.0
H= 0.12
i= 2
Spillway Elev: 5047.8
WQ WS Elev: 5047.92
PATRICK
ENGINEERING
JOB NO. 21273.003 DATE 11/9/2012
PROJECT Pawnee Water Management - Wastewater Recycling Facility
REVISION DATE
WATER QUALITY VOLUME PROVIDED
WATER QUALITY POND (PHASE IZ
STAGE
CONTOUR AREA VOLUME
CUM.
VOL. ELEV.
WQCV
5046.0 0
5047.0
5048.0
5048.5
5845
21163.5
37903
2923
13504
14767
0
2923
16427
31193
*Storage Volume calculated using the the average -end area formula:
V, 2 = ((A, +A2)/2]d
5047.20
WQ VoI= 5,620.2
10-yr VoI= 18,412
100-yr Vol= 26,200
WQ W.S.= 5047.20
*10-yr W.S.=
100-yr W.S. =
OUTLET STRUCTURE ORIFICE CALCULATIONS
Q100 = C*A * ((2*g*H)^.5)
A = 1/4(rrD2)
H10 = Elev,o - Eleywocv+D10/2
H100 = Elev,00 - EleviNv+D,00/2
WQCV Orifices
WQ Discharge:
Centroid:
Discharge Coeff:
Orifice Area:
Diameter:
(24 -hour drain time)
0.065 cf/s
0.10 ft
0.6
0.043
6.16
2.80
sf
si
in
Q,o = 2.04 cfs
4,00 = 5.91 cfs
EIev,Nv = 5047.00 ft
Elevwocv = 5047.20 ft
Elev10 = 0.00 ft
Elev1oo = 0.00 ft
Q = WQVol / 24hr drain time
Centroid = (WQ Surface - Invert out) / 2
(Bently Flowmaster suggested)
A0 = Q / Cd*(2*q*H)^2
- > USE 2 3/4" ORIFICE
Worksheet for Broad Crested Weir - 1
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
Discharge
Gravel
5047.92 ft
5047.80 ft
5047.00 ft
3.00 ft
3.00 ft
0.32 ft/s
0.12 ft
-0.80 ft
2.55 US
1.00
2.55 US
0.36 ft2
0.88 ft/s
3.24 ft
3.00 ft
Bentley Systems, Inc. Haestad Methods StIepakt. vIaster V8i (SELECTseries 1) (08.11.01.03]
11/8/2012 3:57:18 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1
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