HomeMy WebLinkAboutCT 16-07; MARJA ACRES; SEWER STUDY; 2022-09-12
DEXTER WILSON ENGINEERING, INC.
WATER ● WASTEWATER ● RECYCLED WATER
CONSULTING ENGINEERS
2234 FARADAY AVENUE ● CARLSBAD, CA ● (760) 438-4422
SEWER STUDY FOR THE
MARJA ACRES PROJECT
IN THE CITY OF CARLSBAD
September 12, 2022
Jesse Kleist
September 12, 2022
DEXTER WILSON ENGINEERING, INC. PAGE 3
Sewer System Design Criteria
The design criteria used for the evaluation of the offsite sewerage system impacts by the
Marja Acres project are based on the City of Carlsbad Engineering Standards and Sewer
Master Plan. The master plan was also used for verification and confirmation of existing
wastewater facilities surrounding the project.
Relevant sections of the City’s Engineering Standards and Sewer Master Plan regarding the
design criteria for sewer lines and appurtenances are included in Appendix A.
Sewer Generation Rates
Chapter 6 in the City’s Engineering Standards identifies the average daily sewage flow to be
220 gpd per EDU. The City’s Engineering Standards states that an EDU equates to one
single family residence. Some of Marja Acres will consist of apartment-style multi-family
residential units and therefore will likely generate less wastewater than a typical single
family residence. In fact, unlike the City’s Engineering Standards, the City’s Sewer Master
Plan accounts for a lower unit flow factor for high-density residential development (176 gpd
per EDU). Note that the master plan indicates that this lower flow factor is for apartments
only. Residential low density to medium-high density is indicated as 220 gpd per EDU (akin
to the City’s Engineering Standards) in the master plan. The sewer generation rates for the
Marja Acres and the surrounding area are presented as Table 1.
TABLE 1
CITY OF CARLSBAD
SEWER GENERATION RATES
Land Use Generation Rate
Single Family Residential 220 gpd/EDU
Multi-Family Residential (Apartments) 176 gpd/EDU
Industrial (Warehouse) 220 gpd/5,000 ft2
Industrial (Office) 220 gpd/1,800 ft2
Commercial 220 gpd/1,800 ft2
Jesse Kleist
September 12, 2022
DEXTER WILSON ENGINEERING, INC. PAGE 4
Peaking Factors
The peaking factor for sewage flow less than 100,000 gpd is identified in the City’s
Engineering Standards. It states for average daily flows of less than 100,000 gpd, a peaking
factor of 2.5 shall be used to determine peak daily flows. The City’s Engineering Standards
do not state what the peaking factor is for average daily flows that are greater than 100,000
gpd; however, the City’s Master Plan does provide more detail on peaking factors. The master
plan breaks down peaking factors by tributary basin within the City. The tributary basin
that Marja Acres is located in is identified as 17D-3. 17D-3 is shown to have a peak of 1.75
times the average which is what was used for estimating peak sewer flows in this report.
Excerpts from the master plan regarding peaking factors and an e-mail correspondence from
the City are included in Appendix A as well.
Manning=s An@
The gravity sewer analyses are made using a computer program which uses the Manning
Equation for all of its calculations. The Manning=s An@ used by the computer program is held
as a constant for all depths in a circular conduit. The value of Manning=s An@ used for this
study is 0.011 which corresponds with the recommended value in the City’s Engineering
Standards.
Depth and Velocity of Flow in Gravity Sewers
Gravity sewer lines are designed to convey peak dry weather flow. Pipes that are 12-inches
in diameter and smaller are designed to convey this flow with a maximum depth-to-diameter
(d/D) ratio of 0.50. Pipes that are larger than 12-inches in diameter are designed for a
maximum d/D ratio of 0.75. Gravity sewer lines are designed to maintain a minimum velocity
of 2.0 feet per second at peak dry weather flow to prevent the deposition of solids.
Jesse Kleist
September 12, 2022
DEXTER WILSON ENGINEERING, INC. PAGE 5
Estimated Sewer Flows for Marja Acres
Based on the sewage generation factors presented in Table 1, the estimated average sewer
generation for the project is calculated in Table 2 and the estimated peak flow is shown in
Table 3.
TABLE 2
MARJA ACRES
ESTIMATED AVERAGE SEWER FLOW
Land Use Quantity Sewer
Generation
Total (Average)
Flow
Residential
(Townhomes) 248 DUs 220 gpd/DU 54,560 gpd
Residential
(Apartments) 46 DUs 176 gpd/DU 8,096 gpd
Commercial 10,000 sq. ft. 220 gpd/1,800 sq. ft. 1,222 gpd
Total 63,878 gpd
TABLE 3
MARJA ACRES
ESTIMATED PEAK SEWER FLOW
Land Use Average Flow Peaking Factor Peak Flow
Residential
(Townhomes) 54,560 gpd 2.5 136,400 gpd
Residential
(Apartments) 8,096 gpd 2.5 20,240 gpd
Commercial 1,222 gpd 2.5 3,055 gpd
Total 159,695 gpd
(111 gpm)
Jesse Kleist
September 12, 2022
DEXTER WILSON ENGINEERING, INC. PAGE 6
Existing and Proposed Sewer System
There are several existing sewer lines in the vicinity of the Marja Acres project. Figure 2
provides the location of existing facilities in the vicinity of the project. There is an existing
12-inch sewer interceptor in Kelly Drive (labeled NAHT1B in the Master Plan) that conveys
flow south from El Camino Real. From this line in Kelly Drive, an 8-inch sewer line runs
southeast in El Camino Real and has been extended approximately 365 feet easterly in El
Camino Real on account of the Robertson Ranch project which is directly across El Camino
Real from Marja Acres.
The recommended onsite private gravity sewer system is presented on Figure 3.
Sewer System Analysis
Offsite Public Analysis. To analyze the impact of the Marja Acres project on the existing
gravity sewer system, a sewer system analysis was conducted. The system was analyzed
under existing flow conditions and under existing flows plus flow from the Marja Acres
development project. The As-Built drawings and offsite sewer access hole locations included
in Appendix B were utilized to determine the sizes and slopes of the sewer lines analyzed in
this study.
The analyses of the offsite sewer system under both existing flows and existing plus proposed
flows is presented in Appendix C. Exhibit A presents the sewer access hole and pipe diagram
and the public sewer system within the project’s sub-basin. The existing average sewage flow
in the sub-basin flowing in El Camino Real adjacent to the project site was estimated to be
159,055 gpd. This is based on previous sewer studies (Robertson Ranch) and an estimation
of the existing development adjacent to El Camino Real.
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Jesse Kleist
September 12, 2022
DEXTER WILSON ENGINEERING, INC. PAGE 9
The offsite analysis begins at sewer access hole (SAH) 16 in El Camino Real. The wastewater
from the project will enter the existing gravity sewer line in El Camino Real near SAH 12
and SAH 6. The sewer is then conveyed to the 12-inch diameter interceptor in Kelly Drive
approximately 150 feet northwest of the project. The analysis ends at this location (SAH 2).
This interceptor in Kelly Drive joins the North Agua Hedionda Interceptor before flowing
west and being pumped in both the Fox’s Landing Lift Station and Agua Hedionda Lift
Station before eventually being conveyed southward to the Encina Treatment Plant.
The results of the sewer flow analysis indicate that the sewer lines between the Marja Acres
project and the interceptor in Kelly Drive have a maximum d/D ratio of 0.49 under existing
peak flows and 0.60 under existing peak flows with the project included. These flows are in
8-inch diameter gravity sewer lines in El Camino Real where depth ratios of up to 0.50 are
acceptable per the City’s Engineering Standards and Master Plan.
The critical section of this line is the last section prior to the connection to the 12-inch
interceptor in Kelly Drive. This section of line is approximately 280 feet in length and was
installed at a slope of 0.40 percent with a drop manhole at the upstream end to allow the
sewer line to be installed below a gas line and box culvert. The maximum depth-to-diameter
(d/D) ratio in this section of line, with Marja Acres included, during peak flows is 0.60.
While new 8-inch sewer lines are to be designed for a maximum d/D ratio of 0.5, it is
reasonable to allow an existing gravity sewer to flow at a d/D ratio of up to 0.75 during
ultimate peak flows before recommending replacement. An e-mail correspondence with the
City confirming adequate capacity is included in Appendix A.
Onsite Private Analysis. In addition to the offsite analysis, an onsite sewer analysis was
completed utilizing the proposed sewer access hole inverts throughout the project. The onsite
analysis results are presented in Appendix D. Exhibit B presents the sewer access hole and
pipe diagram for the proposed onsite sewer system.
The sewer modeling results show the depth ratios in the proposed onsite gravity sewer lines
to be in compliance with City design criteria. Appendix D includes the proposed onsite utility
layout which includes the invert elevations of the new sewer lines.
Jesse Kleist
September 12, 2022
DEXTER WILSON ENGINEERING, INC. PAGE 10
Conclusions and Recommendations
The following conclusions have been made related to providing sewer service to the Marja
Acres project.
1. The Marja Acres project will sewer its flow to existing City of Carlsbad gravity lines
in El Camino Real.
2. The development of the Marja Acres project is projected to result in average sewage
flow of 63,878 gpd.
3. No offsite gravity sewer improvements are needed to provide sewer service to the
proposed project.
4. There is one section of 8-inch gravity sewer that goes over half-full when adding Marja
Acre’s sewage flow. The depth in this line (0.60 d/D) does remain below critical
replacement level.
5. The sewer system analysis conducted indicates that the existing gravity sewer lines
downstream of the project site can accommodate the wastewater flows for the Marja
Acres project.
6. The proposed onsite layout and pipe sizes of the onsite gravity sewer system is
presented on Figure 3.
APPENDIX A
DESIGN CRITERIA & PEAKING FACTORS FROM
THE CITY OF CARLSBAD
Volume 1 2/16/2016
Page 41 of 54
CHAPTER 6 – DESIGN CRITERIA FOR GRAVITY SEWER LINES AND
APPURTENANCES
Prior to preparation of improvement plans, Engineer-of-work shall submit a rough layout
of system for review and approval by the City Engineer.
1. SEWER MAIN DEPTH AND SIZE
A. Sewer main depth and size shall be as shown below unless approved by
the City Engineer.
B. Minimum depth, finish grade to top of pipe: 6 feet
C. Maximum depth, finish grade to top of pipe: 15 feet
D. Design calculations shall be submitted to verify size and bedding design.
(Manning "N" PVC = 0.011 is norm).
E. Minimum size of mainline shall be 8".
F. 6" main line may be allowed on cul-de-sac streets with a maximum of 10
units.
G. All sewer laterals and main line invert elevations shall be shown in profile on
the improvement plans and shall include stations, slope, and distance.
H. All sewer mains over 15" in diameter shall require special design subject to
City Engineer approval.
2. SEWER LATERAL DEPTH AND SIZE
A. 4" minimum diameter for single-family residence.
B. 6" minimum diameter for all other use.
C. Desirable depth at property line is 5 feet (top of pipe to finish grade @ top of
curb).
3. PIPELINE MATERIAL TYPES
A. 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.
B. 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 2/16/2016
Page 42 of 54
C. 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."
D. 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.
E. Use of other pipe and fitting materials and types may be required by the
City Engineer to meet specific conditions during design or construction.
F. 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.
G. 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
A. 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.
B. 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:
1) 8" minimum 0.40% desirable 0.50%
2) 10" minimum 0.28% desirable 0.40%
3) 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.
C. Gravity pipelines with diameters of 12" and less shall be designed to flow at
depths of 0.5D 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.
Volume 1 2/16/2016
Page 43 of 54
D. Peak hour sewer flow rates do not include infiltration or inflow (I/I).
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 I/I 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 I/I 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.
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 x 2.5
a) Residential: Single Family Residence = 1 EDU
b) Commercial Property: 1 EDU/1,800 ft2 (building space)
i) To convert raw land to square feet of building space, assume 30% coverage. This could vary significantly
dependent development constraints. ii) To convert improved pads to square feet of building
space, assume 40% of coverage.
3) Industrial Property: 1 EDU/5,000 ft2 (warehouse space) 1 EDU/1,800 ft2 (office space)
a) To convert raw land to square feet of building space, assume 30% coverage. This could vary significantly dependent issues such as
environmental restrictions. b) To convert improved pads to square feet of building space,
assume 40% of coverage.
c) Assume 60% of building space is warehouse, and 40% is office space.
5. HORIZONTAL AND VERTICAL LAYOUT
A. Streets: See City of Carlsbad Standard Drawing No. GS-6 for location.
B. Alley: Main to centerline shall be a minimum of three feet (3') offset.
City of Carlsbad DUDEK
SEWER MASTER PLAN 5-5 April 2012
of San Diego Water & Sewer Design Guide recommends the use of 80 gallons per capita day (gpcd),
which equates to 197 gpd/DU for the City of Carlsbad (based on 2.46 persons per household). Based on
these comparisons and the calculated unit flow rate for current conditions, the previously established
flow generation rate of 220 gpd/EDU is considered to be appropriately conservative for flow projections
in this master plan update. A lower unit flow factor of 176 gpd (80 percent of 220 gpd/EDU) is applied
to high-density residential units in excess of approximately 20 units per acre (apartment complexes).
A non-residential land use flow factor of 800 gpd per 10,000 square feet of building area is applied to
commercial and industrial development projections in the Growth Database. The composite
commercial/industrial unit factor was approved by City Staff for planning purposes, and is higher than the
average unit flow calculated in the unit flow analysis documented in Section 3.7. It is noted that
projections made using this factor are based on a mix of development types in existing
business/industrial parks and may not be representative of smaller areas with a single land use type. Flow
projections for future schools, resort hotels, and the expansion of the Legoland Water Park are based
on EDU conversions documented in the Carlsbad Municipal Code (Table 13.10.020c).
The unit flow factors established by City Staff to project ultimate wastewater flows in this Master Plan
Update are summarized in Table 5-2.
Table 5-2 Wastewater Unit Flow Factors
Land Use Category Unit Wastewater Flow
Residential Low Density to Med-High Density 220 gpd/DU
Residential High Density (Apartments) 176 gpd/DU
Commercial/Industrial 800 gpd/10,000 sq ft of building area
High School 7.33 gpd/student
Hotel 132 gpd/guest room
Water Park (Legoland) 3,740 gpd/developed acre
5.4 PROJECTED ULTIMATE FLOWS
Wastewater flow projections for future developments are made by applying the unit flow factors to the
future build-out data in the modified Growth Database. Future wastewater flows are projected to be
approximately 2.1 mgd and are summarized in Table 5-3. The future flows are based on flow projections
for future development, and also include unit counts for existing residences that currently have septic
systems and areas in LFMZ 6 that previously were pumped to LWWD from the La Golondrina and La
Costa Meadows Lift Stations. It is noted that a minor wastewater service area boundary adjustment is
assumed in the future to serve existing LWWD customers within the area of a proposed residential
development located on the west side of El Camino Real, just south of Poinsettia Lane.
1
Steven Henderson
From:David Hull <David.Hull@carlsbadca.gov>
Sent:Tuesday, July 24, 2018 4:48 PM
To:Steven Henderson
Cc:Lindsey Stephenson
Subject:RE: Marja Acres Water and Sewer Studies
Hi Steve,
When I mentioned the issue the City was looking into I had assumed you were referring to the sewer peaking factor
comment we made on the sewer study. We have updated the model and determined that a 1.75 peaking factor is
acceptable. The existing infrastructure will manage the additional waste water flows from the Marja project. We will not
require the developer to make improvements to the public waste water system.
We are still open to a meeting if you have other issues you would like to discuss. Please let me know if you would still
like to meet and I can arrange at time and location.
Thank you,
David Hull, P.E.
Associate Engineer
City of Carlsbad Public Works
5950 El Camino Real
Carlsbad, CA 92008
Office: 760-603-7322
Mobile: 760-497-4044
David.Hull@carlsbadca.gov
From: Steven Henderson [mailto:Steven@dwilsoneng.com]
Sent: Tuesday, July 24, 2018 9:41 AM
To: David Hull <David.Hull@carlsbadca.gov>
Cc: Lindsey Stephenson <Lindsey.Stephenson@carlsbadca.gov>
Subject: RE: Marja Acres Water and Sewer Studies
Hi David,
Thanks for providing the update on your internal model. Have any results been yielded yet?
Steven Henderson, P.E.
Dexter Wilson Engineering, Inc.
Office: 760-438-4422
Cell: 760-542-5910
From: David Hull [mailto:David.Hull@carlsbadca.gov]
Sent: Monday, July 16, 2018 2:31 PM
2
To: Steven Henderson <Steven@dwilsoneng.com>
Cc: Lindsey Stephenson <Lindsey.Stephenson@carlsbadca.gov>
Subject: RE: Marja Acres Water and Sewer Studies
Hi Steven,
The City has been looking into this issue. Our consultant has recently revised the sewer model to reflect the most up to
date information. The preliminary review has indicated that the Marja Acres peaking factor and estimated flows will be
acceptable without an upsize to the system. The City will confirm this result with an updated model run later this week.
At this time lets hold off on meeting.
If the model confirms the system can handle the required flow, the City would not require Marja to revise the sewer
study and upsize the sewer. Let’s plan to touch base when I have the final model results likely Wednesday or Thursday.
Thank you,
David Hull, P.E.
Associate Engineer
City of Carlsbad Public Works
5950 El Camino Real
Carlsbad, CA 92008
Office: 760-603-7322
Mobile: 760-497-4044
David.Hull@carlsbadca.gov
From: Steven Henderson [mailto:Steven@dwilsoneng.com]
Sent: Tuesday, July 10, 2018 11:51 AM
To: David Hull <David.Hull@carlsbadca.gov>
Subject: Marja Acres Water and Sewer Studies
Good Morning David,
My name is Steven Henderson; I prepared the water/sewer studies for Marja Acres. The developer wanted to inquire on
a meeting to review the initial comments and to ensure we can address them on the revised studies. If that sounds okay
to you let me know your availability in the upcoming week or two and hopefully we can get something scheduled.
Thanks,
Steven Henderson, P.E.
Dexter Wilson Engineering, Inc.
Office: 760-438-4422
Cell: 760-542-5910
APPENDIX B
SEWER AS-BUILT DRAWINGS IN EL CAMINO REAL
APPENDIX C
SEWER SYSTEM COMPUTER MODELING RESULTS
EXISTING FLOW &
EXISTING FLOW PLUS THE
MARJA ACRES PROJECT FLOW
DATE:FOR:
BY:Exhibit A
M.G.D.C.F.S.
365.97 16 14 153,865 153,865 1.75 269,264 0.269 0.417 8 0.93 0.140117 0.25333 0.38 0.2739 3.42
302.33 14 12 3,360 157,225 1.75 275,144 0.275 0.426 8 1.40 0.116694 0.22667 0.34 0.2355 4.07
314.22 12 10 0 157,225 1.75 275,144 0.275 0.426 8 2.40 0.089127 0.20000 0.30 0.1982 4.83
256.91 10 8 1,830 159,055 1.75 278,346 0.278 0.431 8 2.00 0.098770 0.20667 0.31 0.2074 4.67
296.67 8 6 0 159,055 1.75 278,346 0.278 0.431 8 0.80 0.156169 0.26667 0.40 0.2934 3.30
316.67 6 4 0 159,055 1.75 278,346 0.278 0.431 8 0.80 0.156169 0.26667 0.40 0.2934 3.30
276.67 4 2 0 159,055 1.75 278,346 0.278 0.431 8 0.40 0.220856 0.32667 0.49 0.3827 2.53
DATE:FOR:
BY:Exhibit A
M.G.D.C.F.S.
365.97 16 14 153,865 153,865 1.75 269,264 0.269 0.417 8 0.93 0.140117 0.25333 0.38 0.2739 3.42
302.33 14 12 3,360 157,225 1.75 275,144 0.275 0.426 8 1.40 0.116694 0.22667 0.34 0.2355 4.07
314.22 12 10 25,960 183,185 1.75 320,574 0.321 0.496 8 2.40 0.103843 0.21333 0.32 0.2167 5.15
256.91 10 8 0 183,185 1.75 320,574 0.321 0.496 8 2.00 0.113754 0.22667 0.34 0.2355 4.74
296.67 8 6 0 183,185 1.75 320,574 0.321 0.496 8 0.80 0.179861 0.28667 0.43 0.3229 3.46
316.67 6 4 37,918 221,103 1.75 386,930 0.387 0.599 8 0.80 0.217091 0.32000 0.48 0.3727 3.61
276.67 4 2 0 221,103 1.75 386,930 0.387 0.599 8 0.40 0.307013 0.40000 0.60 0.4920 2.74
63878
Junction with Kelly Drive
Existing Trailer Park (21 Units)
Existing Commercial (15,000 sf)
dn/D(2)Ca for
Velocity(3)
VELOCITY
(f.p.s.)Remarks
Flow from Robertson Ranch
PEAK FLOW (DESIGN
FLOW)LINE SIZE
(inches)
AS-BUILT
SLOPE (%)DEPTH K' (1)dn (feet)
SEWER STUDY SUMMARY
3/11/2022 Marja Acres Sewer Study (Existing Flows; Existing Pipe)
JOB NUMBER:629-030 Dexter Wilson Engineering REFER TO:
LENGTH
(feet)FROM TO
IN-LINE
FLOW
(gpd)
AVG. DRY
WEATHER
FLOW (gpd)
PEAKING
FACTOR
PEAK
FLOW
(gpd)
Remarks
Flow from Robertson Ranch
Existing Trailer Park (21 Units)
Marja Acres Partial Flow
Marja Acres Partial Flow
Junction with Kelly Drive
SEWER STUDY SUMMARY
3/11/2022
629-030
Marja Acres Sewer Study (Existing plus Project Flows; Existing Pipe)
Dexter Wilson EngineeringJOB NUMBER:
LENGTH
(feet)
PEAK
FLOW
(gpd)
TOFROM
IN-LINE
FLOW
(gpd)
REFER TO:
DEPTH K' (1)
AVG. DRY
WEATHER
FLOW (gpd)
PEAKING
FACTOR dn (feet)dn/D(2)Ca for
Velocity(3)
VELOCITY
(f.p.s.)
LINE SIZE
(inches)
AS-BUILT
SLOPE (%)
PEAK FLOW (DESIGN
FLOW)
1 K' based on n = 0.011
2 dn/D using K' in Brater King Table 7-14
3 From Brater King Table 7-4 based on dn/D
APPENDIX D
SEWER SYSTEM COMPUTER MODELING RESULTS
MARJA ACRES PROJECT FLOW
PROPSOED ONSITE GRAVITY SEWER SYSTEM
DATE:FOR:SHT
BY:Exhibit B
S.A.H. #Elev.S.A.H. #Elev.M.G.D.C.F.S.
128 214 80.6 212 76.8 1,760 1,760 2.50 4,400 0.004 0.007 8 3.00 0.001275 0.02667 0.04 0.0105 1.46
128 212 76.8 210 73.6 1,760 3,520 2.50 8,800 0.009 0.014 8 2.50 0.002793 0.04000 0.06 0.0192 1.60
80 210 73.6 208 72.7 1,760 5,280 2.50 13,200 0.013 0.020 8 1.05 0.006464 0.05333 0.08 0.0294 1.56
62 208 72.7 206 69.9 12,100 17,380 2.50 43,450 0.043 0.067 8 4.66 0.010099 0.06667 0.10 0.0409 3.70
81 206 69.9 204 63.8 1,760 19,140 2.50 47,850 0.048 0.074 8 7.51 0.008764 0.06667 0.10 0.0409 4.07
48 204 63.8 202 60.1 3,300 22,440 2.50 56,100 0.056 0.087 8 7.60 0.010209 0.06667 0.10 0.0409 4.78
194 202 60.1 12 52.4 3,520 25,960 2.50 64,900 0.065 0.100 8 3.98 0.016326 0.08667 0.13 0.0600 3.77
128 126 82.1 124 80.9 1,760 1,760 2.50 4,400 0.004 0.007 8 0.94 0.002280 0.03333 0.05 0.0147 1.04
128 124 80.9 122 78.9 1,760 3,520 2.50 8,800 0.009 0.014 8 1.57 0.003524 0.04000 0.06 0.0192 1.60
128 122 78.9 120 76.9 1,760 5,280 2.50 13,200 0.013 0.020 8 1.58 0.005273 0.04667 0.07 0.0242 1.90
128 120 76.9 118 68.4 1,760 7,040 2.50 17,600 0.018 0.027 8 6.62 0.003433 0.04000 0.06 0.0192 3.19
327 118 68.4 116 65.2 7,040 14,080 2.50 35,200 0.035 0.054 8 1.00 0.017664 0.08667 0.13 0.0600 2.04
51 116 65.2 114 63.9 2,420 16,500 2.50 41,250 0.041 0.064 8 2.47 0.013170 0.08000 0.12 0.0534 2.69
63 114 63.9 112 63.3 12,100 28,600 2.50 71,500 0.072 0.111 8 1.00 0.035881 0.12667 0.19 0.1039 2.40
52 112 63.3 110 62.7 0 28,600 2.50 71,500 0.072 0.111 8 1.02 0.035541 0.12667 0.19 0.1039 2.40
57 110 62.7 108 61.2 0 28,600 2.50 71,500 0.072 0.111 8 2.61 0.022192 0.10000 0.15 0.0739 3.37
173 108 61.2 106 52.7 0 28,600 2.50 71,500 0.072 0.111 8 4.91 0.016187 0.08667 0.13 0.0600 4.15
126 106 52.7 104 50.8 8,096 36,696 2.50 91,740 0.092 0.142 8 1.54 0.037102 0.12667 0.19 0.1039 3.07
116 104 50.8 102 47.1 1,222 37,918 2.50 94,795 0.095 0.147 8 3.23 0.026458 0.10667 0.16 0.0811 4.07
142 102 47.1 6 40.0 0 37,918 2.50 94,795 0.095 0.147 8 4.96 0.021350 0.10000 0.15 0.0739 4.47
153 222 61.8 220 61.1 2,640 2,640 2.50 6,600 0.007 0.010 8 0.50 0.004669 0.04667 0.07 0.0242 0.95
59 220 61.1 218 60.8 1,100 3,740 2.50 9,350 0.009 0.014 8 0.49 0.006693 0.05333 0.08 0.0294 1.11
96 218 60.8 216 60.3 0 3,740 2.50 9,350 0.009 0.014 8 0.50 0.006636 0.05333 0.08 0.0294 1.11
33 216 60.3 202 60.1 0 3,740 2.50 9,350 0.009 0.014 8 0.48 0.006738 0.05333 0.08 0.0294 1.11
135 230 72.1 226 69.2 2,860 2,860 2.50 7,150 0.007 0.011 8 2.15 0.002448 0.03333 0.05 0.0147 1.69
89 226 69.2 224 65.2 0 2,860 2.50 7,150 0.007 0.011 8 4.48 0.001695 0.02667 0.04 0.0105 2.37
32 224 65.2 204 63.8 0 2,860 2.50 7,150 0.007 0.011 8 4.53 0.001686 0.02667 0.04 0.0105 2.37
190 240 81.3 104 77.2 3,300 3,300 2.50 8,250 0.008 0.013 8 2.16 0.002815 0.04000 0.06 0.0192 1.50
148 236 77.2 102 76.5 1,760 5,060 2.50 12,650 0.013 0.020 8 0.49 0.009101 0.06667 0.10 0.0409 1.08
364 234 76.5 6 73.1 7,040 12,100 2.50 30,250 0.030 0.047 8 0.93 0.015777 0.08667 0.13 0.0600 1.76
39 232 73.1 208 72.7 0 12,100 2.50 30,250 0.030 0.047 8 0.97 0.015379 0.08000 0.12 0.0534 1.97
131 132 63.9 130 59.9 1,222 1,222 2.50 3,055 0.003 0.005 8 3.09 0.000872 0.02000 0.03 0.0069 1.54
91 130 59.9 128 56.6 0 1,222 2.50 3,055 0.003 0.005 8 3.60 0.000808 0.02000 0.03 0.0069 1.54
SEWER STUDY SUMMARY
3/11/2022 Marja Acres Sewer Study (Proposed Flows; Onsite)
JOB NUMBER:629-030 Dexter Wilson Engineering REFER TO:
LENGTH
(feet)
IN-LINE
FLOW
(gpd)
AVG. DRY
WEATHER
FLOW (gpd)
PEAKING
FACTOR*
PEAK FLOW
(gpd)
PEAK FLOW (DESIGN
FLOW)
LINE
SIZE
(inches)
DESIGN
SLOPE (%)DEPTH K' (1)dn (feet)dn/D(2)Ca for
Velocity(3)
VELOCITY
(f.p.s.)
TOFROM
1 K' based on n = 0.011
2 dn/D using K' in Brater King Table 7-14
3 From Brater King Table 7-4 based on dn/D
DATE:FOR:SHT
BY:Exhibit B
S.A.H. #Elev.S.A.H. #Elev.M.G.D.C.F.S.
SEWER STUDY SUMMARY
3/11/2022 Marja Acres Sewer Study (Proposed Flows; Onsite)
JOB NUMBER:629-030 Dexter Wilson Engineering REFER TO:
LENGTH
(feet)
IN-LINE
FLOW
(gpd)
AVG. DRY
WEATHER
FLOW (gpd)
PEAKING
FACTOR*
PEAK FLOW
(gpd)
PEAK FLOW (DESIGN
FLOW)
LINE
SIZE
(inches)
DESIGN
SLOPE (%)DEPTH K' (1)dn (feet)dn/D(2)Ca for
Velocity(3)
VELOCITY
(f.p.s.)
TOFROM
161 128 56.6 104 50.8 0 1,222 2.50 3,055 0.003 0.005 8 3.60 0.000808 0.02000 0.03 0.0069 1.54
31 136 53.7 134 53.3 8,096 8,096 2.50 20,240 0.020 0.031 8 1.19 0.009297 0.06667 0.10 0.0409 1.72
50 134 53.3 106 52.7 0 8,096 2.50 20,240 0.020 0.031 8 1.12 0.009597 0.06667 0.10 0.0409 1.72
271 148 79.2 146 71.7 4,620 4,620 2.50 11,550 0.012 0.018 8 2.76 0.003489 0.04000 0.06 0.0192 2.09
123 146 71.7 142 68.5 2,200 6,820 2.50 17,050 0.017 0.026 8 2.63 0.005280 0.04667 0.07 0.0242 2.45
134 142 68.5 112 63.3 5,280 12,100 2.50 30,250 0.030 0.047 8 3.92 0.007669 0.06000 0.09 0.0350 3.01
169 140 72.2 138 69.0 2,420 2,420 2.50 6,050 0.006 0.009 8 1.89 0.002206 0.03333 0.05 0.0147 1.43
194 138 69.0 114 63.9 0 2,420 2.50 6,050 0.006 0.009 8 2.64 0.001867 0.03333 0.05 0.0147 1.43
90 156 70.4 152 69.3 1,320 1,320 2.50 3,300 0.003 0.005 6 1.22 0.003226 0.03000 0.06 0.0192 1.06
109 152 69.3 118 68.4 0 1,320 2.50 3,300 0.003 0.005 6 0.83 0.003925 0.03500 0.07 0.0242 0.84
25,960
37,918
63,878
* Peaking Factor of 2.50 is used onsite due to average flows in the separate tributary areas being less than 100,000 gpd
1 K' based on n = 0.011
2 dn/D using K' in Brater King Table 7-14
3 From Brater King Table 7-4 based on dn/D
EXHIBIT A
OFFSITE GRAVITY SEWER ACCESS HOLE AND PIPE DIAGRAM
EXHIBIT B
ONSITE GRAVITY SEWER ACCESS HOLE AND PIPE DIAGRAM
(EV)(EV)EV
EV
(EV)(EV)