ENGINEERING REPORT GUIDANCE FOR COLLECTION SYSTEMS

Water Protection Program fact sheet
06/2019
Division of Environmental Quality Director: Ed Galbraith
PUB2415

This document provides engineering consultants a comprehensive guide of the Missouri Department of Natural Resources’ recommendations and requirements for an approvable engineering report.

A facility plan is required for wastewater treatment facility projects and projects receiving funding from the department under 10 CSR 20-4. Facility plans are more extensive and detailed documents compared to engineering reports. For more information concerning department funding and requirements visit www.dnr.mo.gov/env/wpp/srf/index.html.

Engineering reports shall be submitted prior to the submittal of a construction permit application for projects involving collection systems (e.g., gravity sewers, pressure sewers, pumping stations and force mains). See 10 CSR 20-8.110(2)(B) and 10 CSR 20-6.010(4).

Engineering reports are not required for:

The following is a sample format for the required engineering report content:

Cover Page
Include the following:

Problem Defined
State the project’s purpose. Describe the existing system, including an evaluation of the existing conditions and problems needing correction. Include any schedules of compliance, enforcement administrative orders or agreements.

Hydraulic Capacity and Organic Waste Load

Existing Systems
Flow and organic loading projections for the design life of the system shall be made using actual data that accurately represents the average and peak flows. Evaluate the probable degree of accuracy of data and flow projections. Include impacts of industrial sources and all critical data and methodology.

New Systems
Estimates for organic loading, design average flow, and design peak hourly flow must include the origin of the flow estimate and any assumptions. Also, consider contributions from industrial facilities and major institutional and commercial facilities.

For consistency, use the following flow definitions:

Peaking Factor = Q Peak Hourly / Q Design Avg = (18 + √P) / (4 + √P)
Where:
Q Peak Hourly = design peak hourly flow
Q Design Avg = design average flow
P = Population in thousands

Impact on Existing Wastewater Facilities
If the new collection system is to serve an existing development, the likelihood of I/I contributions from existing service lines and non-wastewater connections to those service lines shall be evaluated.

Location Drawings
Provide a system map (report size) and include drawings or sketches identifying the site of the project, anticipated location and alignment of the proposed facilities.

Site Evaluation
Provide the following project site information: topography, soils, geologic conditions, depth of bedrock, groundwater level, floodway or floodplain considerations, distance to water supply structures, roads, residences and other pertinent site information.

Engineering Criteria
Provide the design criteria and calculations used to determine design flow, velocity, pipe size and all pumping station calculations, including energy requirements. Indicate whether special accessories and stream crossings are incorporated in the proposed project. Identify any unusual specifications, construction materials and construction methods used in the proposed project. Include any maps, photographs, diagrams and other supporting data needed to describe the system.

Include a discussion of emergency operation, flood protection, alarm system, and access road requirements for pumping stations in accordance with 10 CSR 20-8.130.

Cost Estimate
Cost estimates for capital and operation and maintenance should be included.