INDUSTRIAL GROWTH PLAN- DAVENPORT, IA

Project Overview

The purpose of the 2017 Industrial Growth Plan is to develop a hydraulic strategy for the sanitary sewer system for the City of Davenport, ultimately providing recommendations to extend the sanitary sewer system to develop the Northern and Western Growth Areas.  In the 2015 Sanitary Sewer Investigative Metering – Future Growth Areas project, hydraulic capacity and potential deficiencies were evaluated for Silver Creek, Goose Creek, and Caterpillar basins.  As a follow up, the Public Works Department and the Community Planning and Economic Development Department of the City of Davenport requested to investigate the major trunk sewer lines (West Diversion Tunnel, Jersey Ridge Tunnel and Duck Creek North and South Trunk Sewers) of the City to find ways to strategically grow the sanitary sewer capacity to the Eastern Iowa Industrial Center (Northern Growth), while also evaluating options to extend sanitary sewer to the undeveloped areas in the west part of Davenport (Western Growth). This was done through extensive flow monitoring, and evaluation of portions of the collection system.

Several bottlenecks in the collection system were found during the study. The Fourteenth District sewer along with other trunk sewers east of West Diversion Tunnel are shown to be deficient in capacity during a 10-year rainfall event.  The root cause of the deficiency starts at Jersey Ridge Tunnel (48”) which is a heavily bottlenecked trunk sewer due to trying to transports accumulated flows from three major trunk sewers; Duck Creek North (36”), Duck Creek South (48”), and Pheasant Creek (30”). 

In order to create a hydraulic strategy for the City’s sanitary sewer system, the current system flows and more importantly knowing where excess or deficient capacity existed had to be understood fully. The Available Capacity was determined calculated by subtracting the Peak Hourly Wet Weather for 10 year design storm (PHWW₁₀) from the theoretical capacity of the system. The PHWW₁₀  was developed from extensive flow monitors placed strategically in the collection system.

The final recommendation provided the City with 3 projects to increase the sanitary sewer capacity to the Northern Growth area and 5 projects to extend the sanitary sewer system to the Western Growth areas.  All of the projects were prioritized by short-term, intermediate or long-term and discussed in detail to provide the City with a project description, justification, estimated cost and schedule to implement the plan. 

Project Highlights:

• Reviewed City’s sanitary sewer records – GIS, I&I reports, As-Builts.
• Monitored flow by installing 19 flow meters and three (3) rain gauges.
• Created hydraulic model to project sanitary flow from 10-year rainfall event.
• Created a hydraulic strategy to assist City’s decision-making process for sanitary sewer capacity expansion.