SP20-0002_Staff Report_Attach D- EIR Appx N1-VWD-Water-Sewer-Study

Hallmark‐Barham Specific Plan EIR
Technical Appendices

Appendix N.1
VWD Water/Sewer Study
lNTRODUCTlON

V ALLECITOS WATER DISTRICT

H ALLMARK-B ARHAM WATER AND SEWER STUDY
WORK ORDER # 234061

FINAL T ECHNICAL M EMORANDUM
October 23, 2020
Prepared By: Robe1t Scholl , P.E. and Eileen Koonce
The proposed Hallmark-Barham Development (Project) is a 151-unit multi-family residential development located on 10 acres on Barham Drive between Woodland Parkway and La Moree Road in the City of San Marcos (APN 228-310-01 ).

The Project property is located outside of the Vallecitos Water District (VWD) boundary. The Project is within the Rincon Del Diablo Water District.

The Project property is located in VWD's Sewer Improvement District "A" for sewer service only.

Sewer service is proposed to be provided by VWD.

All new projects undergo evaluation by VWD to determine if the current water and sewer infrastructure is sufficient to accommodate the proposed water demands and sewage generation.

This study projects water demand and sewage generation increases due to the Project densification.

It analyzes the following aspects of VWD's infrastructure and makes recommendations for capital improvements for impacts that are created due to the land use change:
► Water distribution system , including the need to upsize pipelines , install new pipelines , or install flow control facilities
► Water storage , including the need for additional storage and the adequacy of existing storage tanks and reservoirs to serve the proposed development ► Water pump stations , including the need to install new pump stations or upsize existing pump stations to serve the proposed development
► Wastewater collection system , including the need to upsize pipelines and manholes , or the need to install new pipelines and manholes
► Wastewater lift stations , including the need to install new lift stations or upsize existing lift stations to serve the proposed development
► Wastewater land outfall , including the need to construct a parallel land outfall to serve this and other proposed developments
► Wastewater treatment facilities, including the need for obtaining additional capacity at the Encina Water Pollution Control Facility (EWPCF) or for expanding the Meadowlark Water Reclamation Facility (MRF)
Hallmark-Barham Water and Sewer Stud y
DRAFT Technical Memorandum
Octob er 23, 2020

Page 2 of 17 ends

WATER SYSTEM ANALYSIS
Since the Project is within the Rincon Del Diablo Water District , VWD will not evaluate the water systems in this study.

WASTEWATER SYSTEM ANALYSIS
The proposed 10-acre Project lies completely within VWD sewer shed 26C. Figures 1 through 5 show the development 's location in relation to sewer shed boundaries , identify wastewater infrastructure within the vicinity of the development , and identify the downstream collection infrastructure that will be impacted by the development.

Wastewater Flow Projections
The Project property's City of San Marcos 2008 General Plan land use designation was Low Density Residential (Residential 4-8 du/ac). VWD 's 2018 Master Plan based its ultimate wastewater generation planning on this approved land use. The Project is proposing a density increase with the proposed 151 multi-family residential units (Residential 15-20 du/ac).

Table 1 provides the average wastewater flow generated both under the density planned for in the 2018 Master Plan and with the proposed Project. The table shows that the Project will increase the projected average wastewater generation by 20,000 gallons per day.

Table 1 - Project Estimated Wastewater Flows
Land Use Type
2018 Master Plan Land Use Flows
Residential (4-8 du/ac)
Total
Proposed Project Demand
Re·sidential (15-20 du/ac)
Total
Sewer Generation Increase
Area
(acres)

10.00 10.00

10.00 10.00
Duty Factor
(gpd/acre)
1,300
3,300
Water
Demand
d
13,000
13,000
33,000
33,000
20,000
Legend
Affected gravity mains
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Existing Sewer Facilities in
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October 2020
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ENT SERVICES\PROJECTS\WO 200000 • 249999 Pro1ects\WO 234061 • Hallmark Elarfi~hi WS Study\Pfgures\Kallmark-Barham Devel 'ater & Sewer Study_ At1 Figure 3 Legend
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Existing Sewer Facilities in
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arham DevelbpmemWater-& '~e~er $1udy A Figure 5
Hallmark-Barh am Water and Sewer Stud y
DRAFT Technical Memorandum
October 23, 2020

Page 8 of 17 ends

Wastewater Collection System Analysis
The 2018 Master Plan outlines VWD's wastewater system design criteiia which are as follows :

Wastewater Collection Infrastructur e Criteria
The wastewater pipeline criteria to be met both within and downstream of the development are as follows:
► Pipes 12 inches in diameter and smaller: ½ full maximum at peak flow ► Pipes over 12 inches in diameter: ¾ full maximum at peak flow ► Minimum velocity: 2 feet per second
► Maximum velocity: 1 0 feet per second
► Manning 's n for gravity pipes: .013
► Hazen-Williams C-factor for force mains /siphons: 120 ► Slope for pipes 8 inches in diameter and smaller: 0.4% minimum ► Slope for pipes over 8 inches in diameter: to be determined by VWD When flow depth in gravity pipes exceeds maximum levels as stated above, a pipe upsize will be specified.

Waste11 ater Model Scenarios
The following scenarios were modeled to identify system impacts that may be created by the proposed sewer generation , and to recommend any improvements required to provide service to the Project:
► Average Dry Weather Flow with existing flows at the Project site ► Average Dry Weather Flow with the proposed Project
► Peak Dry Weather Flow with existing flows at the Project site ► Peak Dry Weather Flow with the proposed Project
► Peak Wet Weather Flow with existing flows at the Project site ► Peak Wet Weather Flow with the proposed Project
The peak dry weather curve is:

Peak Dry Weather Factor = 2.16 x (Average Dry Weather Flow Ratet 0·16 18 The wet weather peak curve is:

Peak Wet Weather Factor= 2.78 x (Average Dry Weather Flow Ratef 0·087 Hallmark -Barham Water and Sewer Study
DRAFT Technical Memorandum
October 23, 2020

Page 9 of 17 ends

Wastewater Model Results
Modeling focused not only on the sewer collection infrastructure in the direct vicinity of the Project , bl1t also on all downstream infrastructure from the development to Lift Station No. 1 on San Marcos Boulevard that would be impacted by the Project flows (see Figures 1 through 5).

The modeling results showed that there are existing system deficiencies in pipe segments HB-29 through HB-31 under the peak wet weather flows during ultimate build-out conditions as shown in Table 5. The wastewater flow from the proposed Project increases those deficiencies. Table 5 presents a summary of the modeling results from this analysis.

VWD's 2018 Master Plan has identified pipe segments HB-29 through HB-31 for upsizing from 18-inch and 24-inch as CIP #SP-25, a Phase 3 project. Phase 3 projects are planned for construction in the 2026-2030 timeframe .

Master Plan projects address and accommodate the pipeline deficiencies identified herein.

Wastewater Capital Facility Fees paid by this Project will be used towards the construction of these pipelines .

Hallmark-Barham Water and Sewer Study
FINAL Technical Memorandum
October 23, 2020

Page 10 of 17 ends

Table 2 - Wastewater Model Results and Recommended Gravity Main Improvements Wastewater Flows with Existing Density at Project Wastewater Flows with Proposed Project Site Development
Peak Wet PWWF Replacement Peak Wet PWWF Replacement
Pipe ID Length (ft) Diameter Slope Weather Depth-to- Replacement PWWF Depth Weather Depth-to- Replacement PWWF Depth- Number (in) Flow Diamter Diamater (in) to-Dia mater Flow Diamter Diamater (in) to-Dia mater (gpm) Ratio Ratio (gpm) Ratio Ratio
HB-1 248 8 0.036 83 0.20 132 0.25
HB-2 245 8 0.008 83 0.29 132 0.36
HB-3 105 8 0.008 103 0.31 152 .. 39
HB-4 300 8 0.011 104 0.29 153 0.36
HB-5 340 8 0.029 111 0.24 160 0.29
HB-6 94 8 0.064 112 0.20 161 0.24
HB-7 401 21 0.003 1206 0.39 1255 0.40
HB-8 150 21 0.004 1210 0.36 1259 0.37
HB-9 148 21 0.003 1211 0.39 1260 0.40
HB-10 100 21 0.005 1212 0.34 1261 0.35
HB-11 79 21 0.004 1343 0.38 1392 0.39
HB-12 250 21 0.004 1344 0.38 1393 0.39
HB-13 170 21 0.004 1355 0.38 1404 0.39
HB-14 112 21 0.006 1366 0.34 1415 0.35
HB-15 10 18 0.010 1368 0.37 1417 0.38
HB-16 348 18 0.010 2901 0.57 2950 0.58
HB-17 335 18 0.010 2910 0.57 2959 0.58
HB-18 55 18 0.010 2913 0.57 2962 0.58
HB-19 185 18 0.010 2955 0.58 3004 0.58
HB-20 340 18 0.011 2958 0.56 3007 0.57
HB-21 109 18 0.011 2961 0.56 3010 0.57
HB-22 453 18 0.010 2966 0.58 3015 0.59
HB-23 446 18 0.011 2985 0.57 3034 0.57
HB-24 319 18 0.009 2989 0.60 3038 0.61
HB-25 130 18 0.015 3017 0.52 3066 0.52
HB-26 330 18 0.010 3019 0.59 3068 0.59
Hallmark-Barham Water and Sewer Study
FINAL Technical Memorandum
October 23, 2020

Page 11 of 17 ends

Table 2 - Wastewater Model Results and Recommended Gravity Main Improvements Wastewater Flows with Existing Density at Project Wastewater Flows with Proposed Project Site Development
Peak Wet PWWF Replacement Peak Wet PWWF Replacement
Pipe ID Length (ft) Diameter Slope Weather Depth-to- Replacement PWWF Depth Weather Depth-to- Replacement PWWF Depth- Number (in) Flow Diamter Diamater (in) to-Dia mater Flow Diamter Diamater (in) to-Dia mater (gpm) Ratio Ratio (gpm) Ratio Ratio
HB-27 246 18 0.011 3022 0.57 3071 0.58
HB-28 256 18 0.008 3026 0.63 3075 0.64
HB-29 247 18 0.005 3473 0.87 24 0.50 3522 0.89 24 0.50
HB-30 278 18 0.006 3474 0.78 24 0.47 3523 0.79 24 0.47
HB-31 280 18 0.004 3476 >1.0 24 0.53 3525 >1.0 24 0.53
HB-32 280 18 0.014 3507 0.58 24 0.37 3556 0.58 24 0.38
HB-33 30 18 0.147 3526 0.30 24 0.21 3575 0.31 24 0.21
HB-34 104 24 0.010 3530 0.41 3579 0.41
HB-35 57 24 0.004 3532 0.53 3581 0.54
HB-36 335 24 0.006 3532 0.47 3581 0.48
HB-37 197 24 0.006 3547 0.48 3596 0.48
HB-38 85 24 0.014 3684 0.38 3733 0.39
HB-39 304 24 0.002 3684 0.69 3733 0.70
HB-40 292 24 0.003 3684 0.60 3733 0.60
HB-41 20 27 0.015 3685 0.32 3734 0.32
HB-42 204 27 0.003 3685 0.50 3734 0.50
HB-43 200 27 0.002 3711 0.56 3760 0.57
HB-44 85 27 0.006 3711 0.41 3760 0.41
HB-45 230 27 0.004 3712 0.46 3761 0.46
HB-46 170 27 0.006 3721 0.41 3770 0.41
HB-47 135 36 0.003 6240 0.43 6289 0.43
HB-48 128 36 0.005 6266 0.38 6315 0.38
HB-49 140 36 0.007 6267 0.35 6316 0.35
HB-50 470 36 0.004 6269 0.40 6318 0.40
HB-51 184 36 0.003 6284 0.43 6333 0.44
HB-52 36 36 0.004 6286 0.40 6335 0.40
CIP- 25 = T-29 - 31 Phase 3
Hallmark-Barham Water and Sewer Study
FINAL Technical Memorandum
October 23, 2020

Page 12 of 17 ends

Table 2 - Wastewater Model Results and Recommended Gravity Main Improvements Wastewater Flows with Existing Density at Project Wastewater Flows with Proposed Project Peak Wet PWWF Replacement Peak Wet PWWF Replacement
Pipe ID Length (ft) Diameter Slope Weather Depth-to- Replacement PWWF Depth- Weather Depth-to- Replacement PWWF Depth- Number (in) Flow Diamter Diamater (in) to-Dia mater Flow Diamter Diamater (in) to-Dia mater (gpm) Ratio Ratio (gpm) Ratio Ratio
HB-53 146 36 0.004 6286 0.40 6335 0.40
HB-54 318 36 0.004 6649 0.41 6698 0.42
HB-55 39 36 0.004 6649 0.41 6698 0.42
HB-56 319 36 0.004 6650 0.41 6699 0.42
HB-57 38 36 0.004 6650 0.41 6699 0.42
HB-58 139 36 0.004 8917 0.49 8966 0.49
HB-59 294 36 0.004 8919 0.49 8968 0.49
HB-60 12 36 0.017 8919 0.33 8968 0.33
HB-61 438 36 0.005 8922 0.46 8971 0.46
HB-62 229 36 0.005 8924 0.46 8973 0.46
HB-63 371 36 0.006 8927 0.44 8976 0.44
HB-64 124 36 0.005 8930 0.46 8979 0.46
HB-65 167 36 0.005 8932 0.46 8981 0.46
HB-66 201 36 0.004 9228 0.50 9277 0.50
HB-67 91 36 0.005 9231 0.47 9280 0.47
HB-68 220 36 0.005 9234 0.47 9283 0.47
HB-69 286 36 0.005 9237 0.48 9286 0.47
HB-70 210 39 0.004 9332 0.44 9381 0.44
HB-71 176 39 0.003 9334 0.48 9383 0.48
HB-72 271 39 0.002 9336 0.54 9385 0.54
HB-73 297 39 0.002 9339 0.54 9388 0.54
HB-74 452 39 0.002 9341 0.54 9390 0.54
HB-75 337 39 0.002 9344 0.54 9393 0.54
HB-76 123 39 0.008 9537 0.37 9586 0.37
HB-77 58 42 0.004 9539 0.40 9588 0.40
HB-78 308 42 0.003 9541 0.44 9590 0.44
Hallmark-Barham Water and Sewer Study
DRAFT Technical Memorandum
FINAL Technical Memorandu

Page 13 of 17 ends

HB-88 457 42 0.004 9969 0.41 10018 0.41
HB-89 650 42 0.004 9972 0.41 10021 0.41
HB-90 677 42 0.004 9975 0.41 10024 0.41
HB-91 373 42 0.004 9981 0.41 10030 0.41
HB-92 420 42 0.004 9986 0.41 10035 0.41
HB-93 20 42 0.001 9989 0.62 10038 0.62
HB-94 486 42 0.004 10014 0.41 10063 0.41
HB-95 500 42 0.004 10016 0.41 10065 0.41
HB-96 84 42 0.008 10469 0.35 10518 0.35
HB-97 20 42 0.013 10471 0.31 10520 0.31
HB-98 15 42 0.053 14161 0.25 14210 0.25
HB-99 138 42 0.003 14163 0.55 14212 0.55
HB-100 347 42 0.002 14172 0.62 14221 0.62
HB-101 18 42 0.002 14174 0.62 14223 0.62
HB-102 10 42 0.004 14176 0.50 14225 0.50
HB-103 10 42 0.010 14370 0.39 14419 0.39
HB-104 73 42 0.004 14945 0.52 14994 0.52
Hallmark-Barham Water and Sewer Study
DRAFT Technical Memorandum
October 23, 2020

Page 14 of 17 ends

Wastewater Lift Station Analysis
Lift stations are sized for peak wet weather flow with manufacturer's recommended cycling times for pumping equipment. Since the proposed Project is not located in a sewer shed that is served by a lift station , there are no lift station upgrade requirements for this project.

Parallel Land' Outfall Analysis
VWD's existing land outfall is shown in Figure 6. The outfall is approximately 8 miles in length and consists of 4 gravity pipeline sections and 3 siphon sections varying in diameter from 20 inches to 54 inches. VWD maintains the entire pipeline from Lift Station No. 1 to the Encina Water Pollution Control Facility (EWPCF). From Lift Station No. 1 to El Camino Real , VWD is the sole user of this pipeline . From El Camino Real to the EWPCF , the ownership capacity is as shown in Table 3 below:

Table 3 - Land Outfall Capacity Ownership by Agency
Agency Ownership Capacity
Percentage (MGD}
Carlsbad 23.98% 5.00
Vista 17.99% 3.75
VWD 58.03% 12.10
Totals 100.00% 20.85
The Meadowlark Water Reclamation Facility (MRF) has a capacity of 5.0 MGD with a peak wet weather capacity of 8.0 MGD. Therefore, VWD has a combined peak wet weather wastewater collection capacity of 20.10 MGD (12.10 MGD + 8.0 MGD).

VWD's 2014 average daily wastewater flow tlu·ough the land outfall was 7.5 MGD. This conesponds to a peak wet weather flow of 17.5 MGD , which falls within VWD's combined peak wet weather collection capacity.

The 2018 Master Plan estimated that, under approved land uses, VWD has an ultimate build-out average dry weather flow of 14.4 MGD. This conesponds to a peak wet weather flow of 31.7 MGD, which exceeds VWD's combined peak wet weather collection capacity. To accommodate additional wastewater flows from planned development , the 2018 Master Plan recommended conveyance of peak flows to the EWPCF through a parallel land outfall.

The Project propose to generate 20,000 gpd of additional average wastewater flow that was not accounted for in the Land Outfall 's capacity studied in the 2018 Master Plan.

The analysis finds that outfall capacity is currently available to serve the Project's proposed wastewater generation. Wastewater Capital Facility Fees paid by this Project will be used toward design and construction of a parallel land outfall to be sized to accommodate ultimate build-out wastewater flows.

Legend
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Vallecitos Water District
Hallmark-Barham Development Water & Sewer Study
Existing Sewer Facilities in
Study Area
October 2020
Figure 6
Hallmark-Barham Water and Sewer Study
DRAFT Tec hnic al Memora ndum
Oct ober 23, 2020

Page 16 of 17 ends

Wastewater Treatment Facility Analysis
VWD utilizes two wastewater treatment facilities to treat wastewater collected within its sewer service area.
► The Meadowlark Reclamation Facility (MRF) has liquids treatment capacity of up to 5.0 MGD with a peak wet weather capacity of 8.0 MGD . MRF does not have solids treatment capacity , and therefore all solids are treated at the Encina Water Pollution Control Facility (EWPCF) .
► The EWPCF is located in the City of Carlsbad . This is a regional facility with treatment capacity of up to 40.51 MGD. VWD's cunent ownership capacity is noted below.

Solids Treatment Capacity
VWD currently owns 10.47 MGD of solids treatment capacity at EWPCF. VWD 's 2014 average daily wastewater flow was 7.5 MGD. Therefore , the analysis finds that adequate solids treatment capacity exists at this time to serve the Project.

The ultimate average wastewater flow identified in the 2018 Master Plan is 14.4 MGD, resulting in a projected solids treatment capacity deficiency of 3.93 MGD.

Liquids Treatment Capacity
VWD currently owns 7.67 MGD of liquids treatment capacity at the EWPCF in addition to the liquids treatment capacity of 5.0 MGD at MRF for a total of 12.67 MGD of liquids treatment capacity. VWD 's 2014 average daily wastewater flow was 7.5 MGD. Therefore , the analysi s finds that adequate liquids treatment capacity exists at this time to serve the Project.

The ultimate average wastewater flow identified in the 2018 Master Plan is 14.4 MGD , resulting in a projected liquids treatment capacity deficiency of 1. 73 MGD.

Ocean Disposal Capacitv
VWD currently owns 10.47 MGD of ocean disposal capacity at the EWPCF . VWD's 2014 average daily wastewater flow was 7.5 MGD. Therefore , the analysi s finds that adequate ocean disposal capacity exists at this time to serve the Project.

The ultimate average wastewater flow identified in the 2018 Master Plan is 14.4 MGD , resulting in an ocean disposal deficiency of 3.93 MGD.

The District has determined that adequate wastewater treatment and disposal capacity exists for the proposed Project at this time subject to the qualifications referenced in the Conclusions and Conditions.

Hallmark-Barham Water and Sewe r Stud y
DRA FT Technical Memorandum
October 23, 2020

Page 17 of 17 ends

CONCLUSIO N AND CO DITIONS
The Project is expected to increase wastewater flow by 20,000 gallons per day over ultimate flows projected in the 2018 Master Plan.

The Study concludes that the proposed development will result in the following impacts:
► An increase of 20,000 gpd in solids handling , liquids handling and ocean disposal capacity requirements at the Encina Water Pollution Control Facility . ► An increase of 20,000 gpd in the parallel land outfall 's capacity requirement.

The Study also concludes that there are deficiencies in the existing sewer facilities under peak wet weather flows during ultimate build-out conditions without the addition of the Project. The following improvements are needed to mitigate those deficiencies:
► Approximately 805 feet of existing 18-inch sewer main within the Twin Oaks Valley Park residential community (near the NCTD Sp1inter right-of-way) must be replaced with 24- inch main (HB-29 through HB-31) .

VWD 's 2018 Master Plan has identified sewer pipe segments HB-29 through HB-31 for upsizing from 18-inch to 24-inch as CIP # SP-25, a Phase 3 project. Phase 3 projects are planned for construction in the 2026 - 2030 timeframe.

Master Plan projects address and accommodate the pipeline deficiencies identified herein.

Wastewater Capital Facility Fees paid by this Project will be used towards the construction of these pipelines .

The following items are required for providing service to the proposed Project:
► Payment of all applicable Water and Wastewater Capital Facility fees in affect at the time service is committed in accordance with District rules and regulations . ► Construction and acceptance of all on-site water and sewer facilities prior to service .

The District currently has water and sewer capacity available to serve the Project as proposed.

However, the ability to provide water and sewer service in the future depends upon ultimate build out of the Project and could change depending upon the timing of the build-out , as well as build outs of other development projects , continued reliable water supplies from the San Diego County Water Authority , the District 's treatment cap acity at the EWPCF and other factors affecting growth in the District which may change over time.

This Study is based on the current adopted land use utilized in VWD's 2018 Master Plan . The study addresses the incremental facility impacts of this Project only and does not include or consider any additional projects within VWD ' s service area that have deviated from adopted Master Plan land uses . Any land use changes upstream and/or downstream of the Study area may necessitate a revision of any onsite and offsite studies . VWD shall determine if and when revisions to the Study are necessary. Costs for revising this Study shall be borne by the Developer.

San Marcos City CouncilMay 10, 2022

San Marcos City Council
May 10, 2022