ATTACHMENT D
ENVIRONMENTAL IMPACT REPORT
APPENDIX J
WATER & SEWER STUDY
APPENDIX J
Water and Sewer Study
V ALLECITOS WATER DISTRICT
HUGHES CIRCUITS WATER AND SEWER STUDY
WORK ORDER # 260411
FINAL T ECHNLCAL M EMORANDUM
February 21 , 2023
Prepared By: Elizabeth Lopez, Development Services Senior Engineer and Lisa Whitesell, Engineering Technician III
INTRODUCTIO N
The proposed Hughes Circuits project (Project) is a 67,410 square foot Light Industrial development on 2.61-acres, with remainder acreage of 7.85 acres to be a conservation easement for a grand total of I 0.46 acres located on the northeast corner of Pacific Street (APN's 219-223- 20 & 219-223-22) .
The Project is located within VWD's boundaries for water and wastewater service. The property do_es not need to annex, both water and wastewater services can be provided by the Vallecitos Water District (VWD).
All new projects undergo evaluation by VWD to detennine if the current water and sewer infrastmcture is sufficient to accotmnodate 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 ofVWD '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 constmct a parallel land outfall to serve this and other proposed developments.
Hughes Circuits Water and Sewer Study
FfNAL Technical Memorandum
Februa ry 2 l, 2023
► 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).
► Existing VWD water and/or sewer facilities not being utilized for proposed development will need to be abandoned per VWD Standards and Specifications. Asbestos cement pipe shall be properly removed and legally disposed of by the Developer.
WATER SYSTEM ANALYSIS
The proposed 10.46-acre Project lies completely within VWD's 855 Pressure Zone. Figures 1 and 2 show the development's location in relation to pressure zone boundaries , identify pipelines within the vicinity of the development, and identify storage reservoirs that supply the development area.
Water Demand Projections
The City of San Marcos' approved land use designation for the proposed Project is Light Industrial.
The 2018 Master Plan based its ultimate water demand planning on Open Space. Table 1 provides the average water demand generated both under the density planned for the 2018 Master Plan and with the proposed Project. The table shows that Hughes Circuits will increase the projected average water demand from the 2018 Master Plan land use by 3,393 gallons per day.
Table 1 - Project Estimated Water Demands for Hughes Circuits 2018 Master Plan Land Use Demand
Open Space 10.46 200 2,092
Total 10.46 2,092
Proposed Project Demand
Light Industrial 2.61 1,500 3,915
Open Space 7.85 200 1,570
Total 10.46 5,485
Water Demand Increase 3,393
Legend:
~ 920 Zone PRV
• Storage Tank
Affected Pipeline
- 2" Diameter Pipeline
--4" Diameter Pipeline
6" Diameter Pipeline
--8" Diameter Pipeline
- 10" Diameter Pipeline
- 12" Diameter Pipeline
- 16" Diameter Pipeline
- 18" Diameter Pipeline
--20" Diameter Pipeline
--24" Diameter Pipeline
--27" Diameter Pipeline
--30" Diameter Pipeline
- 36" Diameter Pipeline
--42" Diameter Pipeline
-- Unaffected Pipeline
- Proposed Project
- Unaffected Pressure Zones
- Twin Oaks 1028
- Richland 920
- 855Zone
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~ I Hughes Circuits Water & Sewer Study I
Existing Water Facilities in
Study Area
October 2022
FiQure 1
Legend:
Existing Pipelines
-- 6" Diameter Pipeline
- 8" Diameter Pipeline
- 1 O" Diameter Pipeline
- 12" Diameter Pipeline
-- 14" Diameter Pipeline
- 24" Diameter Pipeline
- 30" Diameter Pipeline
-- Unaffected Pipeline
- Proposed Project
CJ 855Zone
E:\Dl:VELOPMENT l,ERVl~RRO JEGT-&.\WO 260000 - [email protected]~ - - - --- - - 1rcu1ts WS '6tudy\Fig~res\Hll,gi_ Circuits Water & Sew, Fig6,IDlef" -... 4
Vallecitos Water District
Hughes Circuits Water & Sewer Study
Existing Water Facilities in
Study Area
October 2022
Figure 2
Hughes Circuits Water and Sewer Stud y
FINAL Techn ical Memorandum
Februa1y 2 1, 2023
Water liJistributi0n System Am,lysis
The 2018 Master Plan water system distribution and pressure criteria are as follows:
Water Distribution Infrastructure Criteria
The water service pressure criteria to be met by this development are as follows:
► Minimum allowable pressure at peak hour demand: 40 psi ► Minimum allowable pressure at max day plus fire demand : 20 psi ► Maximum allowable pressure : 150 psi
The City of San Marcos Fire Marshall has set the required fire demand at 1,500 gpm for the Project.
To avoid excessive velocity and headloss within the distribution system, the following pipeline design criteria was also utilized:
► Maximum allowable velocity:
► Maximum allowable headloss gradient:
► Hazen-Williams C-factor :
Water Model Scenarios
7 feet per second
15 feet per 1,000 feet
130
The following scenarios were modeled to identify system impacts that may be created by the proposed water demands , and to recommend any improvements required to provide service to the Project:
► Average Day Demand with existing demands at the Project site ► Average Day Demand with the proposed Project
► Maximum Day Demand with existing demands at the Project site ► Maximum Day Demand with the proposed Project
► Peak Hour Demand with existing demands at the Project site ► Peak Hour Demand with the proposed Project
► Maximum Day Demand plus Fire Flow with existing demands at the Project site ► Maximum Day Demand plus Fire Flow with the proposed Project Per the 2018 Master Plan, maximum day demands for this project are 300% those of average day demands , and peak hour demands are 620% those of average day demands.
Water Model Results
Modeling focused on the infrastructure in the direct vicinity of the Project. The model found that the Project did not create any distribution system deficiencies under average day demand or maximum day plus fire flow demand conditions.
Hughes Circuits Water and Sewer Study
FINAL Technical Memorandum
February 2 1, 2023
Wa,ter St011age Analysis
The 2018 Master Plan outlines VWD 's potable water storage reservoirs for each pressure zone as follows:
1.5 times ADD (operational storage) + 3.0 times ADD (emergency storage) + fire flow demand= 4.5 times ADD+ fire flow demand
OR
5.0 times ADD, whichever is greater.
The Project is located entirely within the VWD 855 pressure zone. Water storage for this zone is located within the 920 zone and 1028 Twin Oaks pressure zones, as shown in Figure 1. Table 2 shows the required storage in the 855, 920, and 1028 Twin Oaks pressure zones for existing and ultimate build-out (Master Plan) conditions relative to the existing storage provided within each zone.
Table 2 - Existing Reservoir Storage Capacity and Requirements Existing Ultimate Existing
Existing Storage Ultimate Storage Storage
ADD Requirement ADD Requirement Available
Pressure Zone (MGD) (MG) (MGD) (MG) (MG)
855 3.74 6.79 0
920 5.61 50.05 10.40 101.25 18
1028 Twin Oaks 0.66 3.06 73
Totals 10.01 50.05 20.25 101.25 91
The Project will increase the projected average water demand by approximately 3,393 gallons per day as shown in Table 1.
The amount of additional reservoir storage required is 500% of the development's average day demand or:
3,393 gallons * 500% = 16,965 gallons
The analysis finds that water storage capacity is currently available to serve the Project 's increased storage requirements . Master Plan projects address and accommodate the ultimate build-out storage deficiency and Water Capital Facility Fees paid by this project will be used for the increase in storage necessitated by the Project's demand calculated above.
Wateu Pump Sta#on Anal:ysls
Since the proposed Project is located in a pressme zone that is not served by pmnping, there are no impacts to existing or proposed pump stations by this Project.
Hughes Circuits Water and Sewer Study
FINAL Technical Memorandum
Februa1y 21 , 2023
WASTEWATER SYSTEM ANALYSIS
The proposed 10.46-acre Project lies completely within VWD sewer shed 27C. Figure 3 shows 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.
Wa-slewater Ffow Prr0,)ef/i(jms,
The City of San Marcos approved land use designation for the proposed Project is Light Industrial.
The 2018 Master Plan based its ultimate wastewater generation planning on Open Space. Table 3 provides the average wastewater flow generated both under the density planned for the 2018 Master Plan and with the proposed Project. The table shows that the Hughes Circuits project will increase the projected average wastewater generation from the 2018 Master Plan land use by 3,393 gallons per day.
Table 3 - Project Estimated Wastewater Flows for Hughes Circuits Land Use Type Area
acres
2018 Master Plan Land Use Flows
Open Space 10.46
Total 10.46
Proposed Project Demand
Light Industrial 2.61
Open Space 7.85
Total 10.46
Sewer Generation Increase
Residential
Units
Duty Factor
d/ac
1,300
Wastewater Flow (gpd)
0 0
3,393
3,393
3,393
Legend
Affected Gravity Mains
---
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8" Diameter Pipeline
42" Diameter Pipeline
Unaffected Pipeline
Proposed Project
Sewershed 22C
Sewershed 27C
Sewershed 29C
Sewershed 30C
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\ \ \ Hughes Circuits Water & Sewer Study
, Existing Sewer Facilities in
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H NAL Technical Memorandum
February 2 1, 2023
Wastewater- C0/lleeli'on System Ana11sis
The 2018 Master Plan outlines VWD's wastewater system design criteria which are as follows :
Wastewater Collection ln/i'astructur 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: 10 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.
Wastewater 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 d1y weather curve is:
Peak Dry Weather Factor= 2.16 x (Average D1y Weather Flow Ratet 0•1618 The wet weather peak curve is:
Peak Wet Weather Factor= 2.78 x (Average Dry Weather Flow Ratey0•087 Hughes Circuits Water and Sewe r Study
FINAL Technical Memorandum
February 21, 2023
Wastewater Model Results
Modeling focused not only on the sewer collection infrastructure in the direct vicinity of the Project, but also on all downstream infrastmcture from the development to Lift Station No. 1 on San Marcos Boulevard that would be impacted by the Project flows (see Figure 3).
Table 4 presents a summary of the modeling results from this analysis. The modeling results showed that no deficiencies were identified under the currently approved density under peak wet weather flows during ultimate build-out conditions .
• The study shows a new 8-inch PVC Sewer Main will have to be installed down Pacific Street (HC-1 & HC-2) as shown on Figure 3.
Hughes Circuits Water and Sewer Study
FINAL Technical Memorandum
February 21 , 2023
Hughes Circuit~T~ble 4: Wastewater M_o_de_!Besultsi'n~ R_ec~m_mended Gravity Main Improvements Wastewater Flows with Existing Density Wastewater Flows with Proposed Density PWWF Replacement PWWF Replacement Peak Wet PWWF Peak Wet Pipe ID Length Diameter Slope Weather Depth-to- Replacement Depth-to- Weather Depth-to- Replacement PWWF Depth- Number (ft) (in) Flow (gpm) Diamter Diamater (in) Diamater Flow (gpm) Diamter Diameter (In) to-Dia mater Ratio Ratio Ratio Ratio
HC-1 142 8 0.0050 10 0.12 - - 21 0.16 .;,,-,- '. , _ ' • ~ ..,.c HC-2 315 8 0.0050 10 0.12 - I - 21 0.16
■ r-, -:--.-r--::
- ,- . --- - - - - - -
HC-3 306 8 0.0150 161 0.34 - - .... - 172 0.35
L : -., ~--- - - :
HC-4 230 8 0.0070 172 0.43 -- - 'LJ . 183 0.45 --- ,. -. - ..., - HC-5 222 8 0.0080 174 0.42 - - -. 185 0.43 :: ,,_ --•: - HC-6 450 8 0.0080 176 I 0.42 - -..:~ 187 0.44
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HC-7 450 I 8 0.0110 184 0.40 . - Lr 195 0.41
-
-- ·- ,'IC. - - ' -
HC-8 85 8 0.0220 187 0.33 - -- . ~~ - 198 0.34
C
. - -- - -
HC-9 10 42 0.0100 14,268 0.39 ...._--- I ~ 14,279 0.39 .~~ a "', •
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HC-10 73 42 0.0040 14,844 0.52 - - 14,855 0.52 ~ ~~ - - .... ·-~ • ■ ,_ - ~
PROPOSED DENSITY: I 11 !GPM
Hughe s Circu its Water and Sewer Study
FTNAL Technical Memorandum
February 2 1, 2023
Wastewater Lift Statien Analtysis
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 Out.fall Amilysis
VWD 's existing land outfall is shown in Figure 4. The outfall is approximately 8 miles in length and consists of 4 gravity pipeline sections and 3 siphon sections va1ying 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 5 below:
Table 5 - Land Outfall Capacity Ownership by Agency
Agency Ownership Capacity
PercentaQe (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 through the land outfall was 7.5 MGD. This corresponds 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 bui Id-out average dry weather flow of 14.4 MGD. This con-esponds 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 proposes to generate 3,393 gallons per day 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 cun-ently 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
- Outfall - Gravity Mains A
-
Sewershed 21C
- Outfall - Siphon A
-
Sewershed 22C
- Outfall - Gravity Mains B
-
Sewershed 27C
Outfall Siphon B C Sewershed 28C
- Outfall - Gravity Mains C
- Outfall - Siphon C -
Sewershed 29C
-
Sewershed 30C
0 - Outfall - Gravity Mains D
-
Sewershed 31 C
,--
Unaffected Sewer Sheds Sewershed 32C
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Outfall - Gravity Mains B
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Vallecitos Water District
Hughes Circuits Water & Sewer Study
Existing Sewer Facilities in
Study Area
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E:l!JfN~ S~ l~~JECTSIWO 260000 "264999 Projects\Wb 260411 - Hughes Circuits WS Study(Figures\Hughes Circuits Water & Sewer Study Area_Fig4.mxd October 2022
Fiqure 4
Hughes Circuits Water and Sewer Study
FINAL Technical Memorandum
February 21, 2023
Wt1$tewateli Jlueatmenft 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 of3 .93 MGD. Wastewater Capital Facility Fees paid by this Project will be used towards the deficiency to accommodate the solid treatment capacity wastewater flow.
Liquids Treatment Capacity
VWD cmrently owns 7.67 MGD of liquids treatment capacity at the EWPCF in addition to the liquid's 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 analysis finds that adequate liquids treatment capacity exists at this time to serve the Project.
Tbe 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. Wastewater Capital Facility Fees paid by this Project will be used towards the deficiency to accommodate the ultimate average wastewater flow.
Ocean Disposal Capacity
VWD cmTently owns 10.47 MGD of ocean disposal capacity at the EWPCF. VWD's 2014 average daily wastewater flow was 7.5 MGD . Therefore , the analysis 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. Wastewater Capital Facility Fees paid by this Project will be used towards the deficiency to accommodate the ocean disposal wastewater flow.
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 .
Hughes Circuits Water and Sewer Study
FINAL Technical Memorandum
February 2 1, 2023
Page l5 of l5
CONCLUSION AND CONDITIONS
The proposed Hughes Circuits Project is expected to increase average daily water demands by 3,393 gallons per day and wastewater flows by 3,393 gallons per day over the ultimate flows projected in the 2018 Master Plan.
The study concludes that the proposed development will result in the following impacts:
► An increase of 3,393 gallons per day in water demand for proposed project. ► An increase of 16,965 gallons of potable water storage requirement. ► An increase of3 ,393 gallons per day in solids handling , liquids handling and ocean disposal capacity requirements at Encina Water Pollution Control Facility. ► An increase of 3,393 gallons per day in the parallel land outfall's capacity requirement.
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 Final Acceptance by our Board of Directors of all on-site and off-site water and sewer facilities prior to service.
► Install approximately 457 feet of 8-inch PVC Sewer Main down Pacific Street (HC-1 & HC-2) as shown in figure 3.
The District cmrently bas 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 capacity at the EWPCF and other factors affecting growth in the District which may change over time.
This Study is based on the cmTent 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. The results of this study are not the accepted conditions for the development, final conditions shall be pai1 of the construction agreement process or issued separately by the District.