In the world of environmental engineering, a design report is far more than a collection of calculations and drawings. It serves as the architectural blueprint, the legal document, and the operational roadmap for critical public health infrastructure. While specific formats vary by jurisdiction, foundational requirements are codified in official wastewater design manual guidelines that mandate a comprehensive structure ensuring technical soundness, environmental compliance, and long-term operational viability .
This comprehensive guide breaks down the standardized engineering report format mandated by these manuals, providing engineers and project stakeholders a clear roadmap for developing defensible, approvable design documentation that meets regulatory requirements and secures project funding .
Understanding the Purpose of an Engineering Report
Before diving into the specific sections, it is essential to understand what a wastewater design report is meant to accomplish. According to the New York State Environmental Facilities Corporation (EFC), “the primary functions of an engineering report are to identify an infrastructure or water quality problem, discuss various solutions and propose a capital improvement project to address the problem” . The report also justifies the expenditure and, if being used to apply for funding, should satisfy requirements of the financing entity.
An engineering report is a final and comprehensive description of the water quality problem and the proposed solution, including applicable design criteria and data supporting the solution . The report must evaluate potential solutions to the defined problem and clearly demonstrate that acceptable engineering principles were used in the evaluation, that the data supports the conclusions, and that the proposed solution has reasonable expectations of solving the water quality problem .
Engineering Report Preparation Standards
A wastewater design report shall be prepared, stamped, and signed by a qualified professional licensed to practice in the relevant jurisdiction and developed in accordance with the latest editions of applicable standards . These typically include:
- Recommended Standards for Wastewater Facilities (commonly known as the Ten States Standards)
- Recommended Standards for Water Works
- TR-16 Guides for the Design of Wastewater Treatment Works
- State-specific stormwater management and flood risk management guidance
In instances where the design engineer proposes a deviation from the standards, the report must clearly explain and justify the deviation. Facilities must be designed to treat permitted flows and loads .
Minimum Requirements for Funding and Approval
For projects seeking funding through agencies like the Environmental Facilities Corporation, the engineering report must :
- Be current (prepared or updated within the specified timeframe)
- Be the final version, not a draft
- Be stamped and signed on the outside cover by a qualified professional
- Identify the problem and state a capital improvement project as the recommended solution
- Provide an alternatives analysis
- Provide an estimate of the total project cost
- Include or attach project location maps
- Attach the completed engineering report certification
Reports that do not include all required items may not receive funding .
The Core Sections of a Wastewater Design Report
A well-structured report guides readers from understanding the problem, to proposing a solution, and finally, to providing the granular detail needed for construction. While individual manuals may organize these sections differently, the underlying content remains remarkably consistent across jurisdictions.
1. Executive Summary
Provide a brief description of the purpose of the report, need for the project, evaluations conducted, recommended alternative, schedule, cost, and next steps . This section serves as the high-level overview for decision-makers and funding agencies.
2. Definition of the Problem
Succinctly define the water quality issue to be addressed by the project. The recommended alternative will resolve the defined issue . Consider the applicability of the following items:
- Compliance: Violations of existing or proposed discharge permits
- Health and Safety: Health, sanitation, security, and/or cybersecurity concerns
- Infrastructure: Assets needing replacement, aging or inadequate infrastructure
- Asset Management: Project components identified in Asset Management Plans
- Redundancy: Need for backup systems
- Inflow/Infiltration: Issues with excessive water entering the system
- Contamination: Groundwater/surface water contamination concerns
- Growth: Reasonable growth and its impact on design flow rates
- Climate Risk: Physical risk due to climate change, sea level rise, storm surge, flooding, or other extreme weather events
- Compliance: Compliance with current federal, state, and local standards
3. Project Background and History
Site Information
Describe the area(s) under consideration and include :
- Location
- Geologic conditions (soil type, depth to bedrock and groundwater, slope if significant)
- Environmental resources (potentially impacted waterbodies, aquifers, endangered species, wetlands, archeologically sensitive areas, agricultural districts)
- Floodplain considerations including identification of Base Flood Elevation
- Project impacts to Environmental Justice Areas and/or Disadvantaged Communities
Ownership and Service Area
Describe the ownership of the facilities and area(s) being served or to be served :
- Municipality(ies) that own and maintain the existing or proposed infrastructure
- Areas served or to be served
- Outside users requiring inter-municipal/private/industrial agreements
- Industrial discharges or hauled waste
- Population trends and growth (U.S. Census or other data for at least the past twenty years)
- Residential population served, documented or estimated from Equivalent Dwelling Units (EDUs)
Existing Facilities and Present Condition
Provide overview of major system components and include :
- General description and history of major system components with process flow diagram
- Current or future projects on the same site
- Discharge permit conditions and effluent discharge limits
- Documented compliance issues (consent orders, notices of violation)
- Design flows and waste loads (average and peak)
- Existing flows and waste loads from the last three years (average and peak)
- Existing energy consumption (include energy audit results if available)
- Photographs
- History of damage due to storm or flood impacts
4. Basis of Design
This represents the technical heart of the report, providing all foundational data and calculations justifying every design decision .
Design Period and Population
The report must specify the design period (typically 20 years) and design equivalent population, accounting for both residential growth and industrial wastewater contributions .
Wastewater Characterization
The report must define projected flows and loads with precision :
Flow Rates: Critical data points include :
- Average daily flow
- Maximum daily flow
- Peak hourly flow
- Peak wet weather flow into the plant
Wastewater Strength: Beyond flow, the report must characterize pollutant loading through key parameters including :
- Biological Oxygen Demand (BOD₅) in both concentration (mg/L) and mass loading (pounds/day)
- Total Suspended Solids (TSS) in both concentration (mg/L) and mass loading (pounds/day)
Design Factors: Manuals specify “peaking factors” or “maximum flow factors” applied to average flows to calculate peak conditions, ensuring system capacity during high-demand periods .
Temperature Considerations: The design temperature of wastewater must be specified as it significantly impacts biological treatment efficiency.
Receiving Water Characterization
The report must document downstream water uses (water supply, recreation, aquatic life, agriculture) and demonstrate that the proposed discharge will meet water quality standards outside any applicable dilution zone . A detailed outfall analysis is required, including description of the receiving water, location of the point of discharge, and applicable water quality standards .
5. Alternatives Analysis
A key requirement is the systematic comparison of feasible solutions. The engineer must analyze multiple alternatives different treatment processes, pipe routes, or sites ranking them based on cost, energy efficiency, environmental impact, and reliability .
The alternatives evaluation must include :
- Schematic diagrams of each alternative
- Preliminary design for cost estimates
- Total project costs dated and keyed to construction cost indices
- Advantages and disadvantages of each alternative
- Process effluent characteristics for each alternative
- Comparison of process performance
- Environmental assessment including primary and secondary impacts
- Operation and maintenance expenses with energy requirements
- Non-monetary evaluation criteria such as :
- Operability: Ease of operation and maintenance
- Reliability: Proven process/technology to meet permit limits
- Flexibility: Capability to handle variations in hydraulic and waste loads
- Environmental Effects: Odor, noise, visual impacts, footprint
- Expandability: Area available for future expansion
6. Design Data and Calculations
This section demonstrates the technical rigor behind the design through detailed engineering calculations .
Process Design Parameters: Manuals mandate detailed sizing calculations for major units. The necessary calculations for the design of major units must give their capacities, size, equipment, and operation factors under varying conditions and methods of operation .
Mass Balance: A mass balance showing the inter-relationship of units shall be included. If major components or equipment are to be modified in stages, discuss the staging sequence and the future changes necessary .
For treatment facilities, the report must include :
- Influent hydraulic and organic loadings (minimum, average, peak)
- Process selection and basis
- Unit dimensions, rates and velocities, detentions
- Loadings to and removal efficiencies through each unit operation
- Total removal efficiency and effluent quality
- Energy requirements
- Flexibility and reliability considerations
Hydraulic Profile: A hydraulic profile provides a “water level map” of the entire plant, showing water elevation as it flows from influent through each treatment unit to final outfall under both minimum and maximum flow conditions .
Process Diagrams: Wastewater flow diagrams must show process configuration, interconnecting piping, reliability, flexibility, flow measurement, and sampling points. Similarly, solids handling flow diagrams must show process configuration and interconnecting piping .
7. Proposed Facilities and Recommendations
With the problem defined and alternatives evaluated, the report moves to presenting the recommended solution.
Facility Description: This section contains a complete narrative and technical description of all proposed infrastructure collection system, pump stations, treatment plant, and outfall lines.
For collection systems, the report must describe :
- The area of service
- An inventory and map of proposed additions and rehabilitation
- Initial and projected loadings
- Isolation from water supply wells and reservoirs
- Unusual construction problems
- Utility interruption and traffic interference
- Basement flooding prevention during power outages
For pump stations, critical details include :
- Wet well sizing
- Pump selection with system and characteristic curves
- Pumping cycle determination
- Wet well size determination
- Amount of air required for ventilation
- Effects of water hammer analysis
- Power failure provisions including auxiliary power units
- Emergency bypass provisions
8. Operations and Maintenance (O&M)
The report should outline the basis for an O&M manual, which typically includes :
- Plant design basis, including design flows and loads
- Overall description of each process, its purpose, and configuration
- Process data summary presenting design criteria and equipment specifications
- Process schematics showing all normal and alternative flow paths
- Operating procedures, including startup, shutdown, normal operations, and emergency operations
- Instrumentation and control system description
- Process control procedures, including required testing and calculations
- Sampling and laboratory procedures
- Safety procedures
The maintenance manual portion primarily provides information on procedures for maintaining, troubleshooting, and repairing facility equipment .https://www.health.state.mn.us/communities/environment/water/tenstates/index.html
9. Costs and Financing
A responsible design addresses financial reality. The report must include :
- Estimated costs of integral parts of the system for the contemplated installation
- A detailed estimated annual cost of operation
- Cost estimates dated and keyed to construction cost indices, with escalation factors applied
- For public projects, how representative properties and users are to be affected by charges
- Existing debt service requirements and bond retirement schedules
10. Regulatory Compliance and Special Considerations
Compliance Documentation: The report must include statements regarding compliance with State Environmental Policy Acts (SEPA/NEPA), water quality management plans, and applicable permit effluent limitations . A statement expressing sound engineering justification that the effluent from the proposed facility will meet applicable permit effluent limitations or pretreatment standards is required .
Special Considerations: The report must address :
- Odor Control: Provisions for odor control
- Corrosion Control: Material selection and corrosion control measures
- Noise Control: Noise control measures
- Energy Conservation: Energy requirements and conservation measures
- Safety: Safety provisions for both construction and operation
- Redundancy: Critical systems must have redundancy provisions
- Flexibility: Design should incorporate flexibility for future changes
- Aesthetics: Landscaping and aesthetic considerations
11. Plans and Drawings
Construction plans are an integral part of the design package. Drawings must include plan views, profiles, elevations, sections, schematics, notes, and supplementary views . Dimensions and relative elevations of structures, location and form of equipment, location and size of piping, water levels, and ground elevations must be included .
Typical sheet sizes are specified (e.g., 22″ x 36″ or 30″ x 42″), and all drawings must include :
- Title
- Scale
- North arrow
- Date
- Professional engineer’s registration seal
The location plan must show the project site on a regional map as well as on a larger scale map of the district, and should contain the project title, sheet index, and space for approval signatures . Elevation datum used should be indicated, and locations and logs of test borings shall be shown on the plans .
12. Appendices
Technical appendices should include :
- Design tabulations
- Process diagrams (wastewater and solids handling)
- Laboratory testing requirements
- Supporting maps and photographs
- Outline of unusual specifications
- Construction materials and construction methods
- Relevant permit documentation (e.g., discharge permit)
- Engineering report certification
Stakeholder Engagement
During the entire study period, the team shall work in close coordination with local authorities and stakeholders. The report should document :
- Understanding of project features and implementation procedures by service providers
- Commitment by local authorities to actively participate and contribute in project implementation
- Commitment to provide required land for project facilities (free of cost)
- General attitude of users on implementation of the project and their willingness towards solving problems
Conclusion
The design report format mandated by wastewater manuals is not bureaucratic red tape. It represents a proven framework for ensuring critical water infrastructure projects are designed with clarity, accountability, and long-term sustainability.
The five major steps of good planning and design characterization of raw wastewater quality and effluent, pre-design studies to develop alternative processes and selection of final process train, detailed design of the selected alternative, construction, and operation and maintenance of the completed facility must all be reflected in the comprehensive report.
Engineers, scientists, and financial analysts must utilize principles from a wide range of disciplines including engineering, chemistry, microbiology, geology, architecture, and economics to carry out the responsibilities of designing a wastewater treatment plant. The objective of the engineering report is to present the technical and nontechnical issues that are most commonly addressed in the planning and design reports for wastewater treatment facilities prepared by practicing engineers.
By following this structured approach from defining the problem to detailing cost and operation engineers provide a clear, defensible, and comprehensive plan that protects public health and the environment for generations. Whether you’re a consulting engineer preparing your first design report or a reviewer evaluating submitted documentation, understanding this format is essential for successful project delivery and regulatory approval.