HomeMy WebLinkAboutMS 15-13; QUARRY CREEK PA R-1 & R-2; SEWER DESIGN REPORT; 2016-03-07Sewer Design Report
Project No. SDP 15-22 /SDP 15-17/MS 15-13
Private Access Road/ Driveway A
R-1 Sewer 484-5H
QUARRY CREEK PLANNING AREAS R-1 & R-2
City of Carlsbad, Ca
County of San Diego
PREPARED FOR:
CORNERSTONE COMMUNITIES
4365 EXECUTIVE DRIVE, SUITE 600
SAN DIEGO, CA 92121 RECEIyI)
MAR 09'2016
PREPARED BY: LAND DEVELOPMENT
ENGINEERING
rmB&C3~
PLANNING ENGINEERING SURVEYING
3990 RUFF1N ROAD, SUITE 120
SAN DIEGO, CA 92123
(858)560-1141
SB&O JOB NO. R-1 71820.60/R-2 71920.60
((~~No.47107 II
- Exp. 12-31-17 :\ eivijL
TABLE OF CONTENTS
Vicinity Map
Scopeof Report ............................................................................................................................... 1
Quarry Creek Development............................................................................................................1
PlanningArea R-1 & R-2 ...............................................................................................................1
Methodology...................................................................................................................................2
SewerHydraulics............................................................................................................................2
Results.............................................................................................................................................3
Conclusion.......................................................................................................................................3
EXHIBITS
SiteSewer Map..............................................................................................................Map Pocket
APPENDIX
City/CMWD Design Standards Volume I Chapter 6 (Gravity Sewer) Excerpts
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Scope of Report
This report is limited to sewage flow estimates and hydraulic calculations of the proposed public
sewer main and the private sewer mains connections from the R-1 and R-2 sites. The public 8"
sewer will be located in a sewer easement at the southerly project limits, adjacent to the water
quality / detention basins. Since these Planning Areas are part of the Master Quarry Creek
Development, no calculations were prepared to analyze the downstream flow conditions or
potential impacts.
Quarry Creek Development
The Quarry Creek development is located in the City of Carlsbad (City), but is bordered to the
east by the City of Oceanside. The development is situated west of College Boulevard, east of
Interstate 5 and south of Haymar Drive. The development is divided north and south by the
Buena Vista Creek which runs east to west across the middle of the site. The Quarry Creek
development is 155.36 acres in gross project size with the addition of some off-site grading and
improvements. The first phase of Quarry Creek created large sheet graded pads, and
infrastructure for the including public roads, backbone public utilities, and the water quality and
detention facilities to support the entire development.
Planning Area R-1 & R-2
The R-2 area will be a multi-family residential development. A total of 278 units will be
constructed, consisting of various attached product types including 2 and 3 story buildings. A
recreational area with restrooms will be modeled as 1 EDU, for a total of 279 EDUs. A private
8" sewer main will collect onsite flows and discharge into a proposed public 8" sewer line at 2
locations. Several of the buildings located adjacent to the public main may include a direct
connection to the proposed public 8" line.
A copy of the Sewer Site Map is provided in the Map Pocket at the back of the report.
The R-1 area is a similar multi-family residential development. The R-1 area (64 EDU) is
located upstream of the project and will discharge to the 8" public sewer located at the Street
"A" cul-de-sac. A restroom building (modeled as 1 EDU) is expected to be constructed at the
future Cultural Center to be located across Street "A" from the R-1 site. A total of 65 EDU will
discharged to the upstream end of the proposed 8" sewer.
See Proposed Sewer Exhibit located in the Map Pocket.
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Methodology
Public sewer lines are to be designed in accordance with City/ CMWD Engineering Design
Standards Volume I, Chapter 6, as follows;
Hydraulic calculations shall be based upon a normal "n" value of 0.011.
Minimum 8" diameter main (6" mains may be used with a maximum of 10 units).
Sewer mains shall be designed for a minimum velocity of 2 feet per second (peak dry weather).
Depth of flow shall not exceed Mull for 12" diameter pipe and smaller.
Flowrate generation using 1 Equivalent Dwelling Unit (EDU) = 220 gallons per day.
Peaking factors for small basins (<100,000 gpd) are set at a constant 2.5.
Small sewer basins are typically limited in achieving a target cleansing velocity of 2 fps. Due to
the limited sewer demand from the future Cultural Center, and the relatively mild street slope,
the minimum 6" dimeter main will be used for the uppermost public reach, located in Street "A".
Sewer Hydraulics
The following table summarizes the peak flows for the R-1 & R-2 projects;
MH
Tributary
Area EDU
Cumm.
EDU
Daily
Flow
(gpd)
Average
Flow
(mgd)
Peak
Flow
(mgd)
Dia
(in)
Slope
(%)
Depth
(ft)
Velocity
(fps)
R-1 & Future Cultural Center______
10-9 Restroom 1 1 220 0.0002 0.0006 [_6 1.03 0.013 0.60
9 R-1 Private 64 64 14,080 0.014 0.035 8 1.03 0.088 2.00
9-8 Street A 65 14,300 /Public
0.014 0.036 8 1.03 0.089 2.01
R-2 Sewer
8-5 Public
Street A 65 14,300_f0.014] 0.03681.03 0.089_J2.01
5 R-2 (East) 51 11,220 0.011 0.028 8 1.25 0.075 2.00
5-4 Public Sewer 116 25,520 0.026 0.064 8 1.03 0.18 2.35
R-2 (West) 228 50,160
Private
0.050 0.126 8 1.03 0.166 2.87
4-1 Public Sewer I 344 75,680 0.076 0.293 8 1.03 0.205 3.22
Notes:
n value =0.011
Results
A review of the hydraulic results indicates flow depths less than 1/3 full. Peak velocities in the
public mains, except for the reach above R- 1, will be at or greater than the 2 fps threshold.
The private connecting sewer mains will achieve the 2 fps cleansing velocity. Onsite private
mains may be sized at 6" to improve hydraulics. The upper reaches of the private main will not
achieve the desired 2 fps, due to the limited population (future Cultural Center).
Conclusion
The proposed private 8" sewer mains will achieve the target 2 fps cleansing velocity under peak
flow conditions, with depth at or below 1/3 full.
The 6" public main upstream of R- 11, located in Street "A" will not achieve the 2 fps threshold,
due to the limited future sewage demand. The minimum 1% design slope will be used for the 6"
main.
The proposed private main connection form R-1 and R-2 will achieve the 2 fps cleansing
velocity using an 8" main at or slightly steeper than 1% slope. Onsite private mains may be
sized at 6" to improve hydraulics. The upper reaches of the private 6" mains will not achieve the
desired 2 fps, due to the limited population.
APPENDIX
City/CMWD Design Standards Volume I Chapter 6 (Gravity Sewer) Excerpts
CHAPTER 6 - DESIGN CRITERIA FOR GRAVITY SEWER LINES AND
APPURTENANCES
Engineer will submit a rough layout of system for review and approval by the City Engineer prior
to preparation of improvement plans.
1. SEWER MAIN DEPTH AND SIZE
Sewer main depth and size shall be as shown below unless approved by the City
Engineer.
Minimum depth, finish grade to top of pipe 6 feet
Maximum depth, finish grade to top of pipe 15 feet
Design calculations shall be submitted to verify size and bedding design. (Manning
"N" PVC = 0.011 is norm).
Minimum size of mainline shall be 8".
6" main line may be allowed on cul-de-sac streets with a maximum of 10 units.
All sewer laterals and main line invert elevations shall be shown in profile on the
improvement plans and shall include stations, slope, and distance.
All sewer mains over 15" in diameter shall require special design and City Engineer
approval.
2. SEWER LATERAL DEPTH AND SIZE
4" minimum diameter for single-family residence.
6" minimum diameter for all other use.
Desirable depth at property line is 5 feet (top of pipe to finish grade @ top of curb).
3. PIPELINE MATERIAL TYPES
Gravity sewer pipe and fittings shall have PVC conforming to ASTM D3034 for
diameters 4" - 15" and ASTM F 679 for 18" - 24", with integral-bell gasketed joints
(gasket and spigot end joint design). Pipe shall be made of PVC plastic having a
cell classification of 12454-B or 12364-B as defined in ASTM D 1784 and shall have
SDR of 35 and a minimum stiffness of 46 psi according to ASTM D 2412.
All fittings and accessories shall be as manufactured and finished by the pipe
supplier or approved equal and have bell and spigot configurations compatible with
that of the pipe.
Volume 1 - Chapter 6 Rev. 6/30/08
Page 1 of 8
PVC pipe joints shall be elastomeric gasket joints type conforming to Standard
Specifications for Public Works (Greenbook) most recent edition. Rubber gaskets
shall be factory installed and conform to ASTM F 477. Pipe joints shall have been
tested and meet watertight performance requirements of ASTM D 3212, "Joints for
Pipe Using Flexible Elastomeric Seals."
PVC C-900 shall be used for gravity sewer pipelines with depths equal or greater
than 15 feet. Engineering calculations shall be provided to verify that the pipe
material will accommodate the design depth.
Use of other pipe and fitting materials and types may be required by the City
Engineer to meet specific conditions during design or construction.
Service connections to the sewer main shall be watertight and not protrude into the
sewer pipe. All materials used to make the service connections shall be compatible
with each other and with the pipe material to be joined and shall be corrosion proof.
Couplings used for repair, or transition to dissimilar pipe materials shall be
approved by the City Engineer and provide corrosion proof watertight seal.
4. DESIGN PARAMETERS FOR GRAVITY SEWER MAIN SLOPE, FLOW AND DEMAND
Gravity sewer pipelines shall be designed for a minimum velocity of 2 feet/second.
Velocity, unless otherwise stated, shall be calculated from peak dry weather flow.
Pipeline slopes shall satisfy the minimum velocity requirement aforementioned.
Maximum velocities greater than 10 ft/second should be avoided.
Slopes for Specific Pipe Sizes 8 through 12-inch diameter:
8" minimum 0.40% desirable 0.50%
10" minimum 0.28% desirable 0.40%
12" minimum 0.21% desirable 0.30%
Slopes for larger than 12-inch diameter pipe shall be designed to meet flow and
velocity criteria and require specific approval of the City Engineer. Pipelines with
horizontal curvature will require increase slope to achieve minimum required
velocities.
Gravity pipelines with diameters of 12" and less shall be designed to flow at depths
of 0.51D during peak hour dry weather flow. Gravity pipelines with diameters greater
than 12" shall be designed to flow at depths of 0.75D during peak hour dry weather
flow.
Peak hour sewer flow rates do not include infiltration or inflow (Ill). Infiltration is
defined as the addition of groundwater into the sewer collection system and inflow
is the addition of storm water into the sewer collection system. Because sewer
collection system Ill is dependent on a number of factors including season, age of
system, type of pipe material and joints, root intrusion, and presence of storm water
system, the Ill flow rates will vary from system to system. The design of sewer
pipelines connecting to sewer systems known to have I/I, or are susceptible to I/I,
shall utilize peak wet weather flow estimates from the City of Carlsbad Sewer
Master Plan or perform wet weather flow monitoring as directed by the
City Engineer. Gravity pipelines designed to convey wet weather flow shall not
exceed 0.90D for peak hour wet weather flow.
Volume 1 - Chapter 6 Rev. 6/30/08
Page 2 of 8
E. Flowrate Generation
1) An Equivalent Dwelling Unit (EDU) = 220 gal/day, Average Daily Flow (ADF)
2) For ADF less than 100,000 gal/day, a peaking factor (PF) of 2.5 multiplied
times the ADF shall be used to determine Peak Daily Flows (PDF). PDF =
ADF x2.5
Residential: Single Family Residence = 1 EDU
Commercial Property: I EDU/1 ,800 ft2 (building space)
To convert raw land to square feet of building space, assume
30% coverage. This could vary significantly dependent
development constraints.
To convert improved pads to square feet of building space,
assume 40% of coverage.
3) Industrial Property: I EDU/5,000 ft2 (warehouse space)
I EDU/1 ,800 ft2 (office space)
To convert raw land to square feet of building space, assume 30%
coverage. This could vary significantly dependent issues such as
environmental restrictions.
To convert improved pads to square feet of building space, assume 40%
of coverage.
Assume 60% of building space is warehouse, and 40% is office space.
5. HORIZONTAL AND VERTICAL LAYOUT
Streets: See City of Carlsbad Standard Drawing No. GS-6 for location.
Alley: Main to centerline shall be a minimum of three feet (3') offset.
Private Street: Shall require special design and conditions. Easement shall be
20 feet minimum.
Horizontal Curve: SDR 35, PVC pipe may be curved horizontally through
longitudinal bending with the following limitation:
:RieDiametei i..tMinFmunvRadiUs
óf cuatit'e -; 6-inch 150 feet
8-inch 200 feet
10-inch 250 feet
12-inch 300 feet
15-inch 375 feet
City Engineer shall approve curvatures for larger diameter pipe.
Volume I - Chapter 6 Rev. 6/30/08
Page 3 of 8
Vertical Curve: Vertical curves shall be permitted only when specifically
approved by the City Engineer. A detailed design drawing shall be required for
review and approval.
Utility Clearances: Show all underground utilities in both plan and profile.
Provide minimum separation per the State Department of Health Services
"GUIDANCE MEMO NO. 2003-02: GUIDANCE CRITERIA FOR THE
SEPARATION OF WATER MAINS AND NON-POTABLE PIPELINES".
Manholes: Shall be located at areas described as follows:
Maximum spacing of manholes shall be three hundred fifty feet (350') for
mains twelve inches (12") and smaller and five hundred feet (500') for
mains over twelve inches (12") unless otherwise approved by the
City Engineer.
Install manholes at all changes of slope that exceeds 2% and show inlet
and outlet inverts on all manholes.
Install manholes at all changes in horizontal direction.
Install manholes at all intersections of mains.
Install manholes at changes of pipe sizes.
Install manholes at the end of all sewer mains.
All standard manholes shall be a minimum of five feet (6) in diameter
with no steps. Man holes shall be sequentially numbered on the plans
with manhole numbers beginning at the lowest invert. Three-foot stubs
shall be provided for future tie-ins and main extensions.
Manholes shall be PVC lined per Std. Dwg. S-IA when: depth is 15-feet
or greater; slope of sewer pipe coming into the manhole is greater than
7%; all force main discharge manholes; the immediate upstream and
downstream manholes of inverted siphons; drop manholes; on sewer
lines 15-inch and greater; when required by the City Engineer.
Where there is a slope change from steep to flat of 5% or greater, the
manhole at the grade change and the next manhole upstream shall be
PVC lined.
Install manholes for all lateral connection in pipelines 15-inch diameter
and larger.
When intercepting flows from smaller pipelines in manholes, set invert of
a smaller main at % of the depth of the larger main.
Locking manhole lids may be required in unpaved areas as directed by
the City Engineer.
The top cone shall be 6" below finished subgrade. Circular steel covers
shall be placed on the manholes during subgrade preparation and base
rock grade work, in order to keep the sewer system clean. Additionally,
roadwork above live sewer manholes shall require plywood type sheeting
be placed inside the manhole and above the channel to keep any debris
from entering the sewer line.
In unpaved areas, sewer manhole frames and covers shall be set
6"above finished grade with concrete ring and marker post marked
"sewer" per Standard Drawing S-9.
Volume I - Chapter 6 Rev. 6/30/08
Page 4 of 8
H. Cleanouts: Extend beyond permanent pavement when street is a temporary
dead end. See Standard Drawing No. S-6 for type of cap and box.
1. Laterals: Laterals shall be constructed per Std. Dwg. No. S-7. Minimum
horizontal distance from water service, fire hydrants, light standards, electrical
transformers, etc., is 5 feet. Desirable horizontal distance is 10 feet.
Install at right angle or radial to the main.
Laterals shall jnot be located in driveways.
No connections shall be permitted on laterals other than provided in
Standard Drawing No. S-7.
Location of property cleanout: See Standard Drawing No. S-7.
If the lowest plumbing fixture on a property is lower than 2-feet above the
nearest upstream manhole cover, then the owner must provide a
Backwater Valve to prevent a sewage backup onto the property. The
valve must be installed in a valve box for easy access and be visible from
the public right-of-way. The property owner shall be responsible for the
installation and maintenance of the sewer Backwater Valve. The
Backwater Valve shall be shown on the precise grading and improvement
plans.
The Contractor shall install sewer laterals using wye fittings sized and
located as shown on the Approved Plans.
Laterals shall be bedded, backfilled and compacted in the same manner
as the sewer main they are connected to.
J. Steep Slope Protection:
1) Sewer pipelines on 20 percent slopes or greater shall be anchored
securely with a cut-off wall per RSD SP-05 or SP-07, spaced as follows:
Not over 36 feet center to center on grades 20 percent and up to
35 percent;
Not over 24 feet center to center on grades 35 percent and up to
50 percent; and
C. Not over 16 feet center to center on grades 50 percent and over.
K. All sewer mains, not located within the public right-of-way shall be provided with
a minimum 20-foot wide sewer easement. In some special cases, a wider
easement may be required; the City Engineer shall determine size.
All easements shall be easily accessible to City maintenance equipment with all
weather roadways.
Volume I - Chapter 6 Rev. 6/30/08
Page 5 of 8
CONNECTIONS TO EXISTING MANHOLES
New connections to existing manholes where stubs have not been provided shall be
made by core drilling through the walls and base as directed by the City Engineer or
their representative. If intercepting flows from smaller pipelines in manholes, set invert of
a smaller main at 3/4 of the depth of the larger main. Special care shall be used to
facilitate the flow when forming the tributary channel into the existing channel.
MISCELLANEOUS REQUIREMENTS
The City of Carlsbad will only maintain sewer mains located in dedicated City
right-of-ways and easements which have all weather vehicular access.
New sewer lines and appurtenances shall remain plugged and/or disconnected
until the City authorizes its use.
Maintenance of sewer laterals from the main to the building shall be the
responsibility of the property owner.
Sewer laterals constructed from the property line to the building shall be per the
Uniform Building Code.
The vertical cleanout shall be stubbed and capped 3 feet above rough
grade during grading and/or construction of project.
All sewer lateral taps on existing sewer lines shall be by "shewer" or
approved equal. All work will be inspected by a City Representative.
A three-inch (3") high "5" shall be stamped on the curb face at all sewer
lateral locations.
GENERAL GUIDELINES FOR SEWER FORCE MAINS
The developers engineer shall submit a preliminary design report showing the alignment;
pipe size, pressure conditions, pipe materials, a rough layout plan including surge
protection design and flow analysis for review and approval by the City Engineer prior to
the preparation of improvement plans.
Minimum cover of sewer force mains shall be 48 inches (48") from top of pipe to ultimate
finished grade. Top of pipe profile shall be shown on the improvement plans.
Show all other underground utilities in both plan and profile. Provide minimum
clearances per the State of California Department of Public Health (CDPH) "GUIDANCE
MEMO NO. 2003-02: GUIDANCE CRITERIA FOR THE SEPARATION OF WATER
MAINS AND NON-POTABLE PIPELINES".
Sewer force mains shall be High Density Polyethylene (HDPE) manufactured in
accordance with ASTM F714, or ductile iron pipe with polyethylene liner, and exterior
corrosion control as approved by the City Engineer.
Where possible, force mains shall be designed with a continuous uphill slope without
high points so that air-release valves are not required on the force mains. If this is not
possible, provide air-release valves manufactured by Vent-O-Mat.
Dual force mains may be required at the discretion of the City Engineer where
maintenance will be required on a regular basis or due to environmental constraints.
At the discretion of the City Engineer, Force mains longer than 1-mile or with excessive
detention times may require the use of chemical addition to prevent odors at the
discharge location of the force main.
Volume I - Chapter 6 Rev. 6/30/08
Page 6 of 8
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LEGEND
DESCRIPTION
PROPERlY LINE/PROJECT BOUNDARY
RIG/IT-OP-WAY LINE
CURB AND GUTTER
SEWER MAIN
SEWER 401.
£X/517/VQ CONTOUR
DIRECT/ON OF DRAINAGE
SEWER BASIN
R-1 64 EDU
R-2 279 EDU
CULTURAL / EDU CENTER
TOTAL 344 EDU
7
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PRELIMINARY II
CR14 PH/C SCALE
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60 0 60 120 180
FOR REVIEW ONLY
Ell
Exp. 12 31-17 3990 Ruffin Road, Suite 120
IN
658-5BO-1 141
85B-E56C)-Bl 57 Fax ii
flat 7 ' ALLEN L. BUTCHER DATE LU
713-4 2-4-16 71922EX02-PROPOSED SEWER.DWC 71920.20