Capital Village
Phase 3 & 4
2004.35A
Capital Village
Phase 3 & 4
Rancho Cordova
Sacramento County
California
Final
DRAINAGE REPORT
June 29, 2006
Prepared for
RSC ENGINEERING, INC
Prepared By:
CIVIL ENGINEERING
SOLUTIONS, INC.
1325 Howe Avenue Suite 202
Sacramento, CA 95825
(916) 563-7300
JOB # 2004.35A
This document prepared under the supervision of:
The status of this report is
PRELIMINARY unless the
appropriate signature is provided to
the right. Signature will be provided
after review is complete.
© 2006 - Civil Engineering Solutions
Inc
Signature dated:
CIVIL ENGINEERING SOLUTIONS INC
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2004.35A
TABLE OF CONTENTS
1.
Introduction ..................................................................................................... 1
2.
Site ................................................................................................................... 1
3.
Methodology.................................................................................................... 1
4.
Project Description .......................................................................................... 1
5.
Analysis ........................................................................................................... 3
6.
Drainage System .............................................................................................. 3
7.
Summary.......................................................................................................... 4
8.
Water Quality .................................................................................................. 5
Channel ............................................................................................................ 6
Vegetation........................................................................................................ 6
List of TABLES
TABLE-A – CSDS MODELS … ................................................................................ 3
TABLE-I – SUMMARY CSDS MODEL … .............................................................. 4
TABLE-II – WQ-PARAMETER … ........................................................................... 5
TABLE-III – Suitable Plants for Vegetative Treatment … ......................................... 7
List of FIGURES
FIGURE 1 – Vicinity Map … ...................................................................................... 2
FIGURE 2 – WQ Basin Profile w/ Section ………………………………APPENDIX-C
APPENDICES
APPENDIX-A – OVERSIZED EXHIBITS
APPENDIX-B – CSDS DETAILED REPORTS AND SUMMARY TABLES
APPENDIX-C – WATER QUALITY – CHANNEL/ BASIN
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INSERT
FIGURE-1
VICINITY MAP
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2004.35A
1.0 Introduction
This report presents the results of the drainage analysis for Capital Village Phases 3 & 4.
This analysis provides the Hydraulic Grade Lines (HGL’s) at each node (Manholes and
Drain Inlets) of the proposed storm drain system, including; shed areas, the design flows,
and pipe sizes. The site was originally zoned commercial and the existing storm drain
system was designed based on the NOLTE Zone 3 charts, for commercial land use. This
project has been re-zoned medium to high-density residential (RD8-10), 8–10 dwelling
units per acre. The design flows are based on the NOLTE Zone 3 charts.
This stormdrain pipe analysis includes the Phase 1 & 2 systems as well as the
contributing off site shed areas. This was done to assure that the flows and HGL’s
(H&H) for the project development were consistent.
2.0 Site
The site is located south of Highway-50 and east of Zinfandel Drive. The Phase 3 & 4
development sites encompass approximately 30-acre. The project is bound by Zinfandel
Drive on the west, International Drive on the north and Prospect Park Drive on the east.
The south boundary is adjacent to an open space corridor that includes a pedestrian/ bike
path. A commercial lot is being retain on the southeast corner of Zinfandel and
International Drives. This commercial site will not be developed with this project. A
Vicinity/ Location Map is provided on Figure 1.
The FEMA FIRM (602620210E) indicates the site is not within any designated 100-year
Floodplain and is designated Zone-X, 500-year floodplain.
3.0 Methodology
The hydrologic and hydraulic analysis for this project was performed in accordance with
the requirements of Volume 2 of the Sacramento City/County Drainage Manual. The
Civil Solutions Drainage Studio (CSDS) program was used to determine the design flows
and analyze the proposed storm drain system. The design flows are based on the land
uses generated by the Nolte Zone 3 Design Charts.
Commercial and residential land use densities (8-10 du/ac) were used to determine the
proposed condition flows. The Nolte design flows are based on land use and area. These
flow reflect approximately the 2-year to 5-year flow event that would be derived using
the Sacramento Chart Method.
The Water Quality Flows (WQF) were derived using the jurisdictional file SACSWQ.
The WQF are based on the City of Sacramento’s flow rate of 0.18-cfs/ ac.
4.0 Project Description
The original drainage studies for the existing drainage systems were not available. Shed
boundaries and areas were determined from existing improvement plans, County Storm
Drain Maps, topographic maps, aerial maps and project site plans. The off-site sheds
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contributing the system flows were estimated using a recent aerial photograph of the area.
An aerial image showing the existing development adjacent to this site is incorporated
into the Shed Map, Exhibit SH-1 included in APPENDIX-A. SH-1 shows the project
boundaries, lotting and off-site shed areas.
The post project flows and HGL’s for the Phase 3 & 4 Storm Drain systems are shown on
the Exhibit SD-1 and SD-2 (APPENDIX-A). The proposed stormdrain system from
Phase 3 and 4 drains from east to west to Zinfandel Drive and connects to a manhole
south of International Drive. The exiting stormdrain in Zinfandel south of International
Drive is a 15-inch pipe. The proposed stormdrain from Phase 3 is a 30-inch pipe. The
15-inch line will be replace with a 30-inch line.
A Water Quality facility on the southeast corner of Zinfandel and Barden Drive will be
used to provide treatment for the water Quality Flows (WQF). A discussion of the
treatment is provided in the WATER QUALITY section of this report.
This report provides the hydraulics analysis for Phases 3 & 4. Phases 1 & 2 contribute
(25.2 & 17.9) a total of 43.1-acres to Manhole E2 in International Drive. The Capital
Village Phase 1 & 2 Drainage Report includes detailed references and explanations of
these sheds and drainage systems.
The contributing offsite sheds and areas that drain to the intersection at Zinfandel and
International Drives are included in this analysis. The areas and flows are included to
reflect their hydraulic impacts to the storm drain system (HGL’s).
The CSDS drainage model includes the Phase 1 & 2 systems, (lines A & B) plus the two
existing drain lines E & F as shown in Exhibit SD-1, in APPENDIX-A. A total shed area
of 299-acres drains to manhole Node E5 at the intersection of Zinfandel and International
Drives.
1) Phases 1 & 2 (Lines A & B) drain the major portion of the residential parcel north
of International Drive and west of Prospect Park Drive to the open channel
adjacent the east side of the proposed commercial site. Lines A and B contribute
27.6-acres and 17.0-acres respectively to the channel. Line A drains the north
half of the residential development and Line B drains the south half. The channel
drains a total of 44.6-acres to manhole (node) E2. The open channel drains from
north to south and will connect to the existing 54-inch storm drain in International
Drive with a 48-inch drain line at the proposed manhole, at Node E2.
2) Phases 3 & 4 includes the shed south of International Drive and west of Zinfandel
Drive. Approximately 30-acres drains to MH-D33 at Zinfandel Drive then north
to E5 at International Drive.
3) Line E drains from east to west down International Drive and includes the 136.8acre off-site commercial property east of Prospect Park Drive and the 13.6-acres
of street frontage and the condominium site. Lines A & B (Phases 1 & 2)
combine with Line E at Node E2.
4) Line F drains from north to south down Zinfandel to International Dr. A total of
62.1-acres drains to E5 from Line F. The shed area includes the 28.5-acres of offsite commercial from north of Disk and Data Drive, plus the 25.8-acres
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commercial parcel, along the east side of Zinfandel between International and
Disk Drive and 7.8-aces of street frontage.
5.0 Analysis
The existing stormdrain system was designed based on the Nolte Zone 3 flows for
commercial land use. The analyses will also use the Nolte design flows to size the
proposed storm drain system and determine the Hydraulic grade Lines (HGL’s)
throughout the system. These flow are approximately equivalent to the 2 to 5-year event
for the Sacramento Chart Method.
Civil Solutions Drainage Studio (CSDS) program was used to develop the design flows
(hydrology) and compute the HGL’s (hydraulics) for the storm drain systems. Models of
the proposed system are based on the Improvement plans provided by the site engineer.
The land use for the proposed projects site is for 8 –10 dwelling units/ acre and the
commercial land use for the off-site sheds. Table-A lists the CSDS models created for
this report along with the jurisdictional flow file used to generate the design flows. The
electronic files for each CSDS model are included on the CD provided in APPENDIX-B.
A copy of the CSDS program is available as “Freeware” Civils Solutions web site;
www.civilsolutions.com/cs_drainage_studio_drainage_software.htm.
TABLE-A
CSDS MODELS
CSDS Model
Jurisdiction
File name
PH1234_COMB_10-YR_June_0620.PRJ NOLTESZ3
PH1234_COMB_WQ_June_0620.PRJ
SACSWQ
Design
Description
Q-Years
Nolte
Proposed Land Use
ZONE3
WQF
Q=0.18A per WQ
Manual
The Water Quality Flows (WQF) are based on the equation 4 -1 (WQF=CiA) of the
Guidance Manual for On-Site Stormwater Quality Control Measures. The WQF are
based on the City of Sacramento’s flow rate of 0.18-cfs/ ac. The jurisdictional file
SACSWQ was used to generate the Water Quality Flows.
6.0 Drainage System
Phases 3 & 4 stormdrain systems flow from east to west and connect to the stormdrain
system within Zinfandel Drive. Phase 4 is located south of International Drive and west
of Prospect Park Drive. Phase 4 drains west to Phase 3. Phase 3 is located in the
westerly 2/3rds of the site and drains to Zinfandel Drive. The existing stormdrain system
in Zinfandel drains north to the existing manhole (E5) at Zinfandel and International
Drive.
The existing stormdrain pipe is a 15-inch pipe and not intended to convey the flows from
the 30-acre shed from Phase 3 & 4. The existing system flow north to International Drive
is not capable of conveying the flows and will be upgraded. The 15-inch line will be
replaced. The proposed system will connect to the existing manhole (E5) at Zinfandel
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and International Drive and extend approximately 1,100-feet south to pickup the water
quality flows from the proposed Water Quality facility (WQ-out) and manhole D32.
The Water Quality treatment channel/basin is located on the southeast corner of
Zinfandel Drive and Barden Drive. A bypass system is incorporated into the stormdrain
system at Manhole #28 (MH28) upstream of the WQ facility. Flows in excess of the
WQF will flow directly to the downstream stormdrain system in Zinfandel Drive to
minimize the flow and volume passing through the WQ facility. Flows in excess of the
WQF will be conveyed to manhole D31A. A detailed description of the WQ facility is
included in the Water Quality section of this Report.
7.0 Summary
The analysis of the proposed stormdrain system is based on the proposed improvement
plans. The HGL’s for all Manholes and Drain Inlet structures are contained with in the
system and maintained a minimum of 1.77 ft below the Rim or grate elevations. A
summary of the areas, design flows and HGL’s at selected node points are presented in
TABLE-I.
TABLE-I
SUMMARY
CSDS ANALYSIS
DESIGN CONDITION
PH1234_COMB_10-YR_June_0620.PRJ
Nodes
smh28
31A
D33
D34
E5
Area-Ac
Design Flows
cfs
9.55
9.80
9.80
11.99
146.16
28.55
29.05
29.05
25.48
297.55
HGL’s
95.45
94.53
94.56
94.43
93.49
The peak flow for the re-zoned residential land use, combined with the commercial land
use ate Node E5 is 14716-cfs. The proposed condition HGL at Node E5 is 93.49, which
is 0.29-feet lower than the AS-BUILT HGL (93.78) shown on the (improvement) plans
for Capital Center II (Sheet 22/92). The peak flow at Zinfandel and International Drive
(Node E5) for the commercial land use condition is 149.52-cfs. The original condition
HGL at Node E5 is 93.56. (see APPENDIX-B SUMMARY REPORT:J). The proposed
condition flows and HGL’s are less than the original design conditions proposed for the
storm drain system. The proposed residential development flows are slightly less than
the commercial land use model, as should be expected due to the reduced impervious
cover.
Copies of theCSDS Detailed Report and Summary Table are included in APPENDIX-B.
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8.0 Water Quality
Discussions with Sacramento County Storm Water Quality treatment staff indicated that
the preferred treatment for this site is a Vegetated Swale. The Sacramento City/ County
Guidance Manual for On-Site Stormwater Quality Control Measures recommends a
minimum contact time of 7-9-minutes.
The Water Quality facility consist of an off-line channel/ basin system with a By-Pass
manhole. The By-Pass Manhole (smh28) will divert the WQF to the basin/ channel
facility. Two outlet pipe at smh28 will control to flows to the WQ facility. The pipe to
the WQ channel is a 24-inch pipe with and invert elevation set at 93.40. A second outlet
pipe (33-inches) is set with the invert at 94.45. This is the HGL of the WQF at smh28.
Flow depth in excess of the WQF will pass to the downstream stormdrain system (D31A
to D33) without flowing through the WQ facility.
Water Quality treatment is provided for within the composite trapezoidal channel/basin.
The channel is a 2-foot wide trapezoidal section that meanders through the basin bottom.
The basin is “pear shaped” with the widest section at the inlet (WQ-in) This will allow
the flows to spread across a large area and allow the velocities to be reduced and
sediment to settle out.
Based on the Water Quality model (PH1234_COMB_WQ_June_0620.PRJ), a contact
time of 12.7-minutes is provided within the channel/ basin facility. The following Table
II presents the Water Quality Flow (WQF) and contact time for the channel reach.
TABLE-II
WATER QUALITY
PARAMETERS
PH1234_COMB_WQ_June_0620.PRJ
US Node D/sNode Area-Ac Q/Ac WQF Ave Vel Length
fps
ft
WQ-in WQ-out
29.45
0.18 5.30
0.32
245
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Time-min
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Channel/ Basin
The Water Quality Facility is a composite trapezoidal channel and basin. A low flow
trapezoidal channel with a 2-foot wide bottom 1-foot deep with 3:1 side slopes will
meander through the basin (see FIGURES-2 -APPENDIX-C). The channel is
approximately 245-feet long, with an upstream invert at 93.2 and a downstream invert of
93.0.
An additional feature to help minimize standing waters in the proposed channel, are two
(2) 8-inch diameter perforated drainpipes placed 12-inches to 18-inches below the
channel invert. A filter fabric with pea gravel will be placed around the pipes to extend
the life of the sub-drains.
The commercial sites will be developed at a later date. No WQ treatment facilities for
the commercial sites are included with this study. It is anticipated that water quality
treatment such as sediment separator vaults will be provided and incorporated with the
development of the commercial site.
Vegetation
The vegetation selected for this project will need to maintain a height that exceeds the
WQF depths of 1 to 1-1/2-feet. Table-III contains a list of recommended grasses suitable
for vegetated swales. This information is from Sacramento City/ County Guidance
Manual for On-Site Stormwater Quality Control Measures. The vegetation for the
channel should be selected by a qualified landscape or appropriate specialist.
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TABLE III
Suitable Plants for Vegetative Treatment
Common Name
Scientific Name
Persistence
Annual Grasses
Low barley
Hordeum depressum
Perennial Grasses
Spiked Bent
Agrostis scabra
Grass
California Brome Bromus carinatus
Tufted hairgrass
Deschampsia
caespitosa ssp.
Caespitosa
Meadow Barley
Hordeum
brachyantherum
Good reseeding
Mulenvergia regens
Comments
Irrigation necessary if used on Native, loosely clumped, tolerates
dry site
alkaline soils, can withstand
summer drought if saturated in
spring
Good reseeding
Irrigation if used on dry site
Good reseeding in
moist areas
Native, excellent for stabilizing
disturbed areas
Irrigation may be necessary on Native bunchgrass, provides good
very dry sites
groundcover
Good to poor
Must be used in moist to wet
reseeding in moist to
sites otherwise requires
wet sites, requires full
irrigation
sun to partial shade
Good reseeding
Irrigation if used on dry site,
no irrigation on moist site
California
Horeum californicum
Meadow Barley
Deergrass
Maintenance Requirements
Native, densely-tufted bunchgrass,
excellent stabilizer, can w/stand
summer drought if saturated in
spring
Native, forms clumps, tolerant of
alkaline soils, infertile soils and
compacted soils
Good reseeding
No irrigation required
Native, forms clumps, one variety is
very short (<8") tolerates alkaline
and infertile soil
Limited reseeding
Summer irrigation
Native, dramatic tall cover
(Source; Guidance Manual for On-Site Stormwater Quality Control Measures,
Sacramento Stormwater Management Program, Jan. 2000, Appendix D).
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APPENDIX A
OVERSIZED EXHIBITS
SH-1 – SHED MAP
SD-1 – STORMDRAIN MAP
MANHOLE ANALYSIS
SD-2 – STORMDRAIN MAP
DRAIN INLET ANALYSIS
SD-3 – STORMDRAIN MAP
WQ ANALYSIS
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APPENDIX B
CIVIL SOLUTIONS DRAINAGE STUDIO
DETAILED SREPORTS and SUMMARY TABLES
PH1234_COMB_10-YR_June_0620.PRJ
PH1234_COMB_WQ_June_0620.PRJ
CD- DRAINAGE ANALYSES
CSDS MODELS
PH1234_COMB_10-YR_June_0620.PRJ
PH1234_COMB_WQ_June_0620.PRJ
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APPENDIX C
WQ CHANNEL/ BASIN
FIGURE-2: CHANNEL PROFILE
W/ TYPICAL SECTION
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