City of Merced
Wastewater
Collection
System Master
Plan
February 6, 2023
City Council
Presentation
1 January 31, 2023
2 Agenda
• Previous Studies
• Wastewater Unit Rate Update
• Hydraulic Model Results Existing System
• Hydraulic Model with Interim CIP Projects
• Updated Wastewater Flow Projections & EDUs
• CIP Costs
2022 Master Plan Update Built on Previous Work
• 2017 Wastewater Collection System Master Plan Draft
Recommended expansion of existing WWTF instead of building new wastewater treatment plant in North Merced
Recommended project was new trunk sewer bypassing the existing collection system.
• 2020 Wastewater Collection System Hydraulic Model Conversion & South Trunk Sewer Service Alternatives Analysis
Model was converted from ICM to PCSWMM
Model was calibrated using actual flow monitoring data from 2019
BACKGROUND
3 Per-Capita Flow
Analysis
WASTEWATER UNIT RATE UPDATE
4 Parameter
Updated Unit Rate
Values
Previous Planning
Values
Average Per Capita Flow (gpcd) 60 (1)
85Factor of Safety (gpcd) 5
Recommended Per Capita Flow
(gpcd) 65
EDU Density (persons per
household) 3.20
(2) 3.02 (3)
Unit Wastewater Generation Rate
(gpd/EDU) 208 257
1. Average per capita flow based on 2021 flow monitoring efforts, as shown in Table 4-3.
2. The per-capita density of single-family housing units from the City’s Financing Plan and Impact Fee Update Report (December 2021) prepared by Economic & Planning Systems, Inc.
3. The 2030 General Plan defines the average residential density within the City’s SUDP as 3.02 persons/unit.
Serving Existing,
Entitled EDUs, and UC
Merced
5 ADWF = 13.25 MGD
• UC Merced = 1.13 MGD (original)
• Unit rate = 208 gpd/EDU
• Total EDUs = 63,702
Existing System
Hydraulic Model
Results
6 Areas shown with green dots exceed
design criteria Level of Service (LOS).
• G Street
• West Ave.
• Yosemite Ave.
• Bellevue Rd.
UC Merced 2020 Long Range
Development Plan (LRPD)
The 2020 LRPD reduces the 2030 student population from 25,000 students to 15,000 and states
UC MERCED FLOW UPDATE
7 UC Merced wastewater generation reduced from 1.13 MGD to 0.27 MGD reducing the requirement to serve existing and entitled by 4,135 EDUs.
Existing System
Hydraulic Model
Results (Reduced UC
Flows)
8 ADWF = 12.34 MGD
• UC Merced = 0.27 MGD (updated)
• Unit rate = 208 gpd/EDU
• Total EDUs = 59,327
Areas shown in red exceed design criteria
level of service.
• G Street
• West Ave.
Interim System Results
CIP 1
9 CIP 1 = BRPS Operational Change
Force main to R. Street
• Eliminates LOS failure on G Street.
• LOS failure on West Ave. remains.
10 EXISTING INFLUENT TRUNK SEWER
10 Influent Trunk – Existing
Condition
Interim System Results
CIP 1, 3, & 4
11 CIP 3 & 4 – West Ave. & 48-inch Interceptor:
Replace 48-inch Interceptor and West Ave.
sewers with 60-inch diameter sewer starting at
V Street and West Ave. and ending at the
WWTF.
Interim System Results
CIP 1, 2, 3, & 4
12 CIP 2 – Parallel Sewer & Bear Creek
Crossing: New 48-inch parallel sewer and
creek crossing starting Bear Creek Ct. and
ending at V Street and West Ave.
Interim System Results
CIP 1, 2, 3, 4, 5
13 CIP 5 – Yosemite Sewer Extension & Fahrens
Creek Crossing: A new 27-inch extension of
the Yosemite Avenue sewer starting at G Street
and ending at El Redondo Drive.
Interim System Results
CIP 1, 2, 3, 4, & 5
14 ADWF = 12.34 MGD + 1.14 MGD = 13.48 MGD
EDU = 58,032 + 5,480 = 63,512
Interim System Results
CIP 1, 2, 3, 4, 5, & 6
15 ADWF = 12.34 MGD + 1.87 MGD = 14.21 MGD
EDU = 58,032 + 9,000 = 67,032
Interim CIP Projects
16 CIP No Name Length (LF) Buildout Pipe
Size (in) Construction Cost
1 BRPS FM Discharge Change (1) - - 0
2 Parallel Sewer & Creek Crossing 6,500 48 $4,634,333
3 West Street (2) 1,900 60 $1,207,000
4 48-inch Interceptor (2) 14,700 60 $10,868,667
5 Yosemite Sewer Extension 5,100 27 $1,793,000
6 Parallel G Street Sewer 8,000 27 $1,979,000
Description Cost
Subtotal $20,482,000
5% Mobilization/Demobilization $1,025,000
Construction Cost Subtotal $21,507,000
30% Contingency $6,453,000
Estimated Construction Cost $27,960,000
20% Engineering, Environmental, & Admin $5,592,000
Total Project Cost $33,552,000
17 Updated
Wastewater
Flow
Projections
Service Area Total Area
(Acres)
Total
EDUs ADWF (MGD)
Existing Service Area (1) 6,497 33,029 6.88
• UC Merced (2) 200 673 0.14
Total Existing 6,697 33,702 7.02
Interim Service Area
• General Plan Land Use Parcels 2,737 19,669 4.09
• City Specified Land Use Parcels 82 788 0.16
• Single Lot Parcels/ 1 EDU 407 2,129 0.44
• Specific Development Plan Parcels 311 2,417 0.50
• UC Merced (committed ADWF exceeding existing, 0.13 MGD) (2) 380 625 0.13 • Pre-Annexation Areas (5) 155 9,000 1.87
Subtotal Interim 4,072 34,628 7.19
Buildout Service Area
• Pre-Annexation Areas (Remaining) 1,555 8,912 1.86
• Remaining Parcels within SUDP (General Plan) Boundary (3) 9,313 49,642 10.33 • Campus Community (planning ADWF estimate, 0.84 MGD) (4) 1,106 4,038 0.84 Subtotal Buildout 11,974 62,592 13.03
Total Interim Service Area 10,769 68,330 14.21
Total Buildout Service Area 22,743 130,923 27.24
1. The existing total EDU estimate is approximate and was provided by the City; existing system flows are based on flow monitoring data independent of actual EDUs.
2. UC Merced wastewater flow equates to the projections provided in the 2020 UC Merced Long Range Development Plan Recirculated Draft Subsequent Environmental Impact Report, (December 2019). The existing flow is approximately 0.14 MGD with an addition of
0.13 MGD projected under future conditions resulting in a total flow of approximately 0.27 MGD.
3. The area and EDU estimate of parcels bisected by the City’s SUDP boundary are limited to the portion that exists within the City’s planning area.
4. ADWF estimate from Table 2.0-8 of the UC Merced and University Community Project Final EIS/EIR (March 2009), scaled to reflect changes to the wastewater unit rate (208/257). See Section 4.1 of this report.
5. After model completion, the amount of available capacity for pre-annexation areas, after implementation of proposed improvements, was considered. These available EDUs and flow capacity are listed here.
CIP Costs
COSTS SUMMARY
18 Item Area of Improvements Total Cost
1 Interim System Improvements $33,552,000
2 North Merced Major Improvements $56,835,000
3 South Merced Major Improvements $18,182,000
Subtotal Major Improvements $108,569,000
4 North Merced Minor Improvements $12,536,000
5 South Merced Minor Improvements $4,456,000
Subtotal Minor Improvements $16,992,000
Total Improvements Cost $125,561,000
•Costs based on ENRCCI (20 Cities Index) = 13,175, October 2022.