Copperhead Engineers
Copperhead Engineers
Project Description
The following project is associated with the Water Environment Federation student design competition, in partnership with AZ Water Association. The project is meant to design a completely new, 30 million gallon per day (MGD) Advanced Water Purification Facility (AWPF). In conjunction with the preexisting 91st Avenue Wastewater Treatment Plant (WWTP) and Tres Rios Flow Regulating Wetlands (FRW), located in Tolleson Arizona. The facility is to use Physical Separation and Advanced Oxidation Process (AOP).
The 91st Ave WWTP opened in 1958, expanding the facility in the early 2000s to increase the water produced by the facility. In 2012 the Tres Rios Wetlands opened next to the WWTP and have continually undergone restoration efforts near the Salt and Gila Rivers.
Figure 3: 91st Avenue Wastewater Treatment Plan
Project Location
Figure 5: Vicinity Map
Figure 4: Location Map
Figure 6: Site Map
Land Area & Site Boundary
One of the biggest limitations for our design is the amount of available land for the new AWPF. The AZ Water SDC prompt requires that all new construction stays within City-owned property, which significantly narrows down where we can place treatment units. The parcels near the 91st Avenue WWTP and Tres Rios Wetlands vary in size, development density, and environmental sensitivity, so we had to carefully evaluate where each process could realistically fit. Because membrane systems, UV-AOP reactors, chemical storage, and brine-management facilities all have large spatial needs, we had to prioritize a compact layout and reduce unnecessary piping or routing. This constraint pushed our team to make efficient, space- conscious design decisions from the start.
Regulatory & Treatment Performance
Our treatment train must comply with strict state and federal regulations, especially the Arizona Advanced Water Purification Rule and EPA drinking-water standards. These rules require very high pathogen removal (up to 13-log virus and 10-log protozoa) and multiple independent treatment barriers, so we couldn’t freely choose any treatment process we wanted. To meet these standards, the AWPF must include MF/UF, RO, and UV-AOP at a minimum. These regulations affect equipment sizing, chemical dosing, monitoring requirements, and redundancy, and they eliminated a few alternative options early in the evaluation process. Only the alternatives capable of meeting potable-reuse quality standards were carried forward.
Brine Management
Because the design requires reverse osmosis, we must account for the brine concentrate the system produces. The challenge is that the site has limited land area and no easy disposal pathway, which makes traditional evaporation or large brine-handling systems difficult. The SDC prompt also highlights that brine management is a key part of the project, so we had to evaluate options like blending, deep-well injection, or solids management. Each option comes with cost, environmental, and operational impacts, which played a major role in determining which treatment trains were feasible.
Hydraulic Grade Line & Pumping
The
proposed AWPF receives water from
the Tres Rios Flow Regulating Wetlands
Outfall, which is at a lower
elevation than our treatment systems.
To overcome this, the prompt
requires designing a new pump
station capable of lifting flow to the AWPF.
This impacts almost every part of the design:
· Pump sizing and energy demand
· Headloss across membranes and AOP
· Piping lengths and elevations
· Building elevations and pad heights
If the hydraulic profile
didn’t work for a treatment
alternative, we had to remove it from consideration.
Construction Phasing & Operational
The 91st Avenue WWTP treats about 230 MGD and must stay fully operational during construction. Because of that, any design we propose can't interfere with existing flows, pipelines, or the wetlands discharge system. Our site is also tight, which makes it harder to move large construction equipment or stage materials. The SDC prompt requires a full construction phasing plan, so we had to think about how the AWPF could be built in stages without interrupting current operations. This influenced where we placed major structures and how we planned the sequencing.
Time & Scheduling Constraints
The overall project timeline is very tight. Based on our team’s Gantt schedule, the entire design spans 140 working days, with multiple tasks on the critical path — especially treatment selection, hydraulic analysis, and cost estimation. These activities must be completed on time to meet the SDC deadlines for the 30%, 60%, 90%, and final deliverables. Because we are balancing technical design, research, modeling, cost development, and outreach planning on top of our coursework, the schedule limited how many alternative treatment trains we could explore in depth. Time constraints required strong coordination across sub teams to prevent delays.
Budget & Life Cycle Cost
O&M costs,
and lifecycle cost estimates. RO and UV-AOP
are energy-intensive processes, so cost was a major deciding factor when comparing
alternatives
Budget constraints influenced:
·Membrane type and size
·Chemical storage decisions
·Pump efficiency and head requirements
·Piping layout and building footprint
If an alternative was too expensive or unrealistic for a municipal agency to adopt, we had to remove it from consideration.
Community, Environmental, & Outreach
The AWPF is located next to neighborhoods, public recreation areas, and the protected Tres Rios Wetlands. Because of this, our design must minimize odors, noise, and visual impacts. We also had to consider environmental protection, educational access, and chemical-storage safety. The competition requires a public outreach plan, which means our final design must be understandable and acceptable to the community. This shaped our decisions about building placement, public-access pathways, and the overall presentation of the facility.
Located in SW Phoenix Arizona
Figure 4: Location Map
West of the AZ Loop 202 and South of the I-10
Figure 5: Vicinity Map
In red the possible parcels are highlighted
Figure 6: Site Map
Figure 7: Gantt Chart
The project is organized into eight major task groups that run from late October 2025 through mid-April 2026. The timeline starts with Task 1.0: Research Preparation (WEF application and regulation research), followed by Task 2.0: Site Assessment (site visit and data analysis). We then move into Task 3.0: Treatment Selection Process, where we define plant requirements and evaluate key treatment processes such as coagulation/flocculation, sedimentation, membrane filtration, advanced oxidation, UV disinfection, final chlorination, and brine management. The schedule then transitions into Task 4.0: Final Design (detailed treatment design, site layout, hydraulic analysis, public outreach plan, and construction phasing), followed by Task 5.0: Cost Assessment, Task 6.0: Impact Analysis, and Task 7.0: Project Deliverables, which include our 30%, 60%, 90%, and final design packages, as well as the competition report and final presentation. Task 8.0: Project Management runs in parallel throughout the project for schedule, resource management, and team meetings.
The critical path represents the sequence of tasks that directly controls the overall project completion date. Any delay in one of these activities will immediately delay the entire capstone project. Because of this, the critical path is the most important part of our project schedule. For our engineering capstone, the critical path includes the core technical work and required deliverables, such as site assessment, treatment process selection, hydraulic and final design, cost analysis, impact evaluation, and the 30%, 60%, 90%, and final design submittals. These tasks must happen in a specific order and cannot be skipped or significantly overlapped without
affecting the project outcome.
By closely monitoring the critical path, we ensure that essential technical decisions are completed on time, revisions can be made without schedule failure, and our final design is delivered by the required deadline. This approach reflects real-world engineering project management practice, where controlling the critical path is necessary to protect schedule, quality, and accountability.
Table 1- Staffing
Role Description
SENG - They oversee engineering design processes such as client meetings and design review. The SENG will not have as many billable hours as the rest of the engineering roles due to their higher billable rate.
PM - The P.M. is a direct point of contact for technical and non-technical roles throughout the facility design.
PE - The PE handles the more complex design tasks and reviews the work of lower-level engineers before it is reviewed by the SENG.
EIT - The EIT is in charge of completing data collection and organization, calculations and analysis, reports, and preliminary designs of the project. Depending on the knowledge and experience of the EIT, responsibilities can vary. The EIT is the first point of contact for the intern when there are questions but can go up the chain of command if the answer is unknown.
INT - This role is minimal, working on redlines, simple drafting, some calculations, and data collection. The intern can also oversee preliminary research such as finding existing conditions and historical information on the project site.
Table 2- Cost of Engineering Services
