May 15, 2025
Patrick Dobbins, PE
City of Gonzales
[email protected]
Subject: Proposal for Engineering Services for Municipal Wastewater Treatment Plant Preliminary Design Dear Patrick Dobbins:
We are pleased to provide this proposal for engineering design services for the rehabilitation and upgrade to the Municipal Wastewater Treatment Facility (MWWTP). This proposal includes the evaluation and comparison of MWWTP process upgrades and evaluation of the interim rehabilitation projects required by the Regional Board.
We will document the results of these analyses and recommendations in a Preliminary Engineering Report (PER) The Dudek team presented within this proposal has the resources to perform all work required for each of the Project Tasks as included in the Project Scope of Work. We are proposing to utilize N2W Engineering to provide process analysis and modeling services as part of the project team. Those tasks to be completed by N2W are identified within the Scope of Services
Scope of Services
TASK 1 PROJECT MANAGEMENT
This task addresses the management responsibilities associated with proper scheduling review, budget control, invoice preparation and coordination with the City, its Program Manager, and the Dudek project team. We propose to submit monhtly progress reports. The task includes a Kick-off meeting (in-person), monthly progress meetings, (8 virtual), and a Draft PER review workshop (in-person).
TASK 2 PROCESS UPGRADE DESIGN DATA
Specific design data are required to support the preliminary design effort. Under Task 1.2, Dudek will collect site specific data related to projected wastewater flow to the MWWTP, as well as the influent wastewater characteristics and effluent discharge criteria. It is noted Dudek has compiled most of the needed information during conduct of previous work for the City, including design of the Industrial Wastewater Treatment Facility (IWTF). As a result, the following design data are projected to be derived.
Task 2.1 Flow & Solids Loading Data
Dudek will request recent flow and pertinent constituent concentration data over the last few years. It will be important to determine contributions of flow and loads from industrial dischargers, as these will be diverted to the TO: PATRICK DOBBINS
SUBJECT: PROPOSAL FOR MUNIICAPL WASTEWATER TREATMENT PLANT PRELIMINARY DESIGN MAY 2025 2
IWTF and away from the MWWTP. Dudek has compiled several years of data and will utilize the most recent requested information to determine more accurate design criteria for the future MWWTP upgrades project.
An analysis will be completed to determine future flows and loads anticipated by the City that will be treated at the MWWTP. These data can be taken from existing City documents (e.g., recent City Wastewater Master Plan) or can be developed as part of this project. These criteria will help ensure the upgraded MWWTP will serve the City in the short term and for the next several decades.
Task 2.2 Identification of Required Permits
Dudek will document anticipated regulatory agencies involved in the rehabilitation and upgrade of the MWWTP.
The preliminary list includes:
CEQA – Determination/document type will be based on project definition Regional Board/DDW – Updated discharge permit
AQMD – Required if City adds backup generators or large pump stations (> 1 MGD) TASK 3 PROCESS UPGRADE ALTERNATIVES ANALYSIS
Dudek assumes that the main upgrades at the MWWTP will be to the biological treatment process and will be aimed at improving BOD, TSS, and nitrogen removal. Other improvements may include upgrades to the headworks and the addition of flow equalization. Dudek assumes no additional treatment (e.g., tertiary filtration, disinfection, solids handling) will be required as part of this project.
Task 3.1 Biological Treatment Process Upgrade Alternatives (Up to 3 Alternatives) Dudek suggests that up to three (3) biological treatment alternatives will be evaluated. The evaluation will include effluent water quality goals and provide detailed process descriptions for each of the following alternatives. The three proposed alternatives to be considered are:
1. Sequenced lagoon aeration. This process utilizes a series of aerated lagoons to facilitate biological nutrient removal, with alternating cycles of aerobic and anoxic conditions to effectively reduce nitrogen levels. This approach is cost-effective and can handle varying flow rates, but typically requires a larger footprint and longer retention times compared to other methods.
2. Traditional oxidation ditch with anoxic tank. This process utilizes an oxidation ditch combined with an integral anoxic tank to promote biological nutrient removal through both nitrification and denitrification processes. This approach is proposed for its ability to provide consistent treatment efficiency, handle varying loads, and offer a smaller footprint compared to other alternatives. Aeration is provided by surface aerators.
3. Closed loop reactor. This process utilizes a deeper oxidation ditch with fine bubble diffused aeration and blowers that can be sequenced on and off to control nitrification/denitrification. This approach is proposed for its more compact design, higher treatment efficiency and operator control, and ability to effectively manage fluctuating flow rates and load variations.
Process modeling (BioWin/SUMO) Dudek will run process modeling software (e.g., BioWin) to simulate the performance of the three new wastewater treatment system alternatives. A calibrated model of the existing MWWTP will not be created. BioWin is a wastewater treatment process modeling tool designed to analyze and optimize the performance of wastewater treatment systems, ensuring accurate predictions and efficient system TO: PATRICK DOBBINS
SUBJECT: PROPOSAL FOR MUNIICAPL WASTEWATER TREATMENT PLANT PRELIMINARY DESIGN MAY 2025 3
design. This approach allows for the optimization of critical design parameters, such as footprint, hydraulic retention time, aeration requirements, chemical dosing etc., ensuring that each system operates at peak efficiency.
Conceptual layouts and footprint requirements Dudek will develop conceptual layouts for each (up to 3) alternative processesto ensure the design is both efficient and adaptable, aligning with the project’s specific needs.
Lifecycle costs (capital and O&M). Dudek will assess the lifecycle costs, including both capital, and operations & maintenance (O&M) cost estimates, to provide a comprehensive understanding of the long-term financial implications of the project. This assessment will involve evaluating initial capital costs, such as design, construction, and installation, as well as ongoing O&M costs, including labor, maintenance, energy, and other operational expenses.
Non-monetary considerations (ease of operation, level of control, ability to treat peak flow/load, odor potential, reuse potential, etc.). Dudek will assess non-monetary factors, such as ease of operation, level of control, peak flow/load treatment capabilities, odor potential, and reuse potential. This will help identify the most feasible and effective alternative that aligns with the city’s needs and requirements.
Task 3.2 Process Upgrade Preferred Alternative
Through collaborative efforts with the City, Dudek will develop the Process Upgrade Selection Criteria and Ranking, including the creation of ranking parameters and weighting factors. This will be followed by process ranking and selection using a paired comparison analysis to identify efficient and reliable wastewater treatment solutions. The paired analysis facilitates deliberate discussion and evaluation of alternatives, focusing on assigning relative weights for the developed criteria for each alternative. In a workshop format, input from critical City staff will be captured to define scores for each alternative.
For example, if criterion A (applications), as shown in Table 1, is compared to criterion B (constructability) and B is found to be more important, B will be noted in the weighting table. Each alternative was given an absolute score of 1 to 5 per criterion. These scores were multiplied by the relative weight of the respective criterion and then summed for each technology.
Table 1. Process Selection Criteria and Weighting Factors for Alternatives Deliverables: Draft and Final Technical Memorandum – MWWTP Process Upgrades Alternatives Evaluation
A B C D E F G H
A Demonstrated in Previous Applications B C D E F G H 0% B Constructability B D E F G H 7%
C Operational Complexity C E F G H 7%
D Treatment Complexity E E D H 11%
E Capital Cost F E H 21%
F O&M Cost F H 18%
G Footprint / Truck Access H 11%
H Regulatory Requirements 25%
No. Criteria Weight
Priority
TO: PATRICK DOBBINS
SUBJECT: PROPOSAL FOR MUNIICAPL WASTEWATER TREATMENT PLANT PRELIMINARY DESIGN MAY 2025 4
TASK 4 CEQA COMPLIANCE
Task 4.1 Notice of Exemption
The City of Gonzales is required to comply with the California Environmental Quality Act (CEQA) when considering approval of a “project.” The PER process will identify and evaluate feasible treatment alternatives to upgrade the MWWTP, identify a preferred alternative, and identify next steps for design, funding, and construction. Acceptance of the PER by the City will not constitute “approval” of the MWWTP Upgrades or commit the City to a particular course of action. Therefore, the PER should be considered a “feasibility and planning” study within the meaning Guidelines Section 15262, and is exempt from CEQA review at this time.
Subsequent planning and design (including 30% design), funding approval, and release of bid documents will be subject to CEQA review. In addition, if Clean Water State Revolving Fund financing is sought for final design and construction of the MWWTP Upgrades, the City must also demonstrate compliance with applicable federal environmental regulations (also known as “federal crosscutters”). Appropriate environmental assessments will be prepared as part of that process.
Deliverables: Notice of Exemption
TASK 4 PRELIMINARY ENGINEERING REPORT PREPARATION (10% DESIGN) Dudek will prepare a preliminary engineering report (PER). The PER will define the selected MWWTP process upgrades and rehabilitation projects. It is anticipated that the Regional Board will collaborate with Dudek and the City of Gonzales to develop the PER. The PER will include the following:
1. Introduction
a. Background
b. Purpose, Goals & Objectives
c. PER Content
2. Design Criteria
a. Existing and Projected Design Flows
b. Influent Wastewater Characteristics
c. Effluent Discharge Requirements
d. Wet Weather Flow Management
3. Process Upgrade Preliminary Design
a. Equipment sizing
b. Process calculations & system hydraulics
c. Preliminary site layout
d. Preliminary P&IDs
e. Preliminary drawing list
4. Project Implementation Analysis
a. Preliminary construction cost opinion
b. Preliminary annual O&M cost opinion
c. Preliminary Present Worth analysis
d. Construction Sequencing
e. Preliminary project schedule (final design, bidding, and construction) f. Environmental requirements
g. Permitting requirements
TO: PATRICK DOBBINS
SUBJECT: PROPOSAL FOR MUNIICAPL WASTEWATER TREATMENT PLANT PRELIMINARY DESIGN MAY 2025 5
h. Applicable codes (fire and safety), building/planning/zoning department requirements i. Site considerations, flood elevations, drainage requirements, etc. j. Standby power requirements & criteria
k. Electrical demand coordination with PG&E
l. SCADA requirements
m. Operator certification requirements
n. Funding assistance
o. Procurement options
Deliverables: Draft Preliminary Engineering Report and Final Preliminary Engineering Report Fee Proposal
Dudek proposes a not-to-exceed project budget of $234,959 to complete all the tasks identified in the Scope of Servies. A full breakdown of estimated labor hours by category for each task are attached.
We look forward to continuing our work on this project with you and the City and to providing the services described herein. Please do not hesitate to call or email me (760.479.4262 or [email protected]) with any questions you might have about our proposal.
Respectfully Submitted,
___________________________________ _____________________________________ Mike Metts, P.E. Greg Ripperger, P.E.
Practice Director Senior Project Manager
Mike Metts is authorized to sign on behalf of Dudek.
City of Gonzales
MWWTP PER
Engineering Design Services
DUDEK FEE ESTIMATE
May 15, 2025
Project Team Role: QA/QC
Project
Manager
Senior
Engineer Project Engineer Admin
Team Member: Metts Ripperger Struglia Hawkinson Goldschmidt Kinney
TOTAL DUDEK DUDEK LABOR OTHER DIRECT
Billable Rate : $320 $275 $280 $255 $190 $160 HOURS COSTS Fee COSTS TOTAL FEE Task 1 Project Management and Project Status Reporting
1.1 Project Meetings 16 32 16 64 $ 18,000 $ 31,990 $ 49,990
1.2 Coordination with Regional Board and other Stakeholders 8 24 32 $ 9,160 $ 9,160
1.3 Invoicing, schedule updates, progress reports 16 16 $ 4,400 $ 4,400
1.4 QA/QC 16 16 $ 5,120 $ 5,120
Subtotal Task 1 40 72 16 128 $ 36,680 $ 31,990 $ - $ 68,670 Task 2 Design Data
2.1 Flow & Solids Loading Data 4 4 16 24 $ 5,160 $ 14,253 $ 19,413
2.2 Identification of Required Permits 4 8 8 24 44 $ 10,080 $ 10,080 Subtotal Task 2 4 12 12 40 68 $ 15,240 $ 14,253 $ - $ 29,493 Task 3 Alternatives Analysis
3.1 Biological Treatment Process Upgrade Alternatives (up to 3) 16 16 $ 4,400 $ 59,241 $ 63,641
3.2 Process Upgrade Preferred Alternative 4 4 8 $ 2,380 $ 2,380
3.3 Draft TM - MWWTP Process Upgrades Alternatives Evaluation 4 8 12 $ 3,480 $ 3,480
3.4 Final TM - MWWTP Process Upgrades Alternatives Evaluation 2 4 6 $ 1,740 $ 1,740 Subtotal Task 3 10 32 42 $ 12,000 $ 59,241 $ - $ 71,241 Task 4 CEQA Compliance
4.1 File Notice of Exemption 4 4 $ 1,120 $ 1,120
Subtotal Task 4 4 4 $ 1,120 $ - $ - $ 1,120
Task 5 Preliminary Engineering Report Preparation (10% Design)
5.1 Draft Preliminary Engineering Report 2 8 16 32 6 64 $ 13,960 $ 43,336 $ 57,296
5.2 Final Preliminary Engineering Report 2 4 8 16 2 32 $ 7,140 $ 7,140 Subtotal Task 5 4 12 24 48 8 96 $ 21,100 $ 43,336 $ - $ 64,436 Total Non-Optional Hours and Fee 58 128 4 52 88 8 338 $ 86,140 $ 148,819 $ - $ 234,959 Percent of Hours: 17% 38% 1% 15% 26% 2% 100%
Subconsultant
N2W