Digital Database Assists USEPA Grant Funded CSO Reduction Plan

The City of Burlington is located near the southeastern corner of Iowa on the Mississippi River and has a population of about 28,000. Burlington has 23 CSOs, and the largest CSO comes from the Hawkeye Trunk Sewer, which serves about two thirds of the City. The Hawkeye Trunk Sewer was constructed in the late 1800s and ranges in size from a 10 foot arch to a 18 foot arch.The City received a 7 million USEPA grant to help cover the 13.3 million cost for the following work:GPS location of 1,350 manholesManhole inspection of 1,350 manholesSmoke testing of 350,000 linear feet of sewerDyed water flooding at 120 locationsTelevision inspection of 350,000 linear feet of sewerFlow monitoring at 29 temporary locations for 60 daysFlow monitoring at 21 permanent sitesRainfall monitoring at three permanent sitesDevelopment of a digital sewer map with “point and click” access to the databaseRehabilitation of cost effective defects to reduce infiltration and inflowConstruction of new storm sewers to separate the combined areasConstruction of a new sanitary interceptor sewer inside the Hawkeye Trunk SewerMany of the City's records were from the 1800s, and the existing maps were not highly reliable. Therefore, part of the City's plan was to obtain digital aerials of the drainage area from the County. These aerials were then used as a base map for the sewer system that would ultimately be compatible with a Geographic Information System (GIS) to be selected by the City at a later date. This map was to become the primary means of retrieving the field data collected using “point and click” technology. A model of the sewer system, which is discussed below, was developed using the digital map and the sewer database.To support electronic collection of the data, telemetry was used to transfer depth and velocity readings from the 21 permanent meter sites into the computerized database. In addition, rainfall data from the three rain gauge sites was also electronically transferred into the database. All defects identified during smoke testing, manhole inspection, and dyed water flooding were recorded using digital photographs. These digital photographs were electronically linked with the digital aerial map as part of the “point and click” database accessibility plan.The database was delivered on digital video disks (DVDs).An internet web page was used to provide the status of smoke testing during the project so that owners could know when to expect the crews. In addition, if owners were on vacation, they could check to see if the work had already been completed in their area.