Friday, April 20, 2007 - 5:16am
Analysis shows water demand can be met while replacement well is being developed
Madison-Water Utility officials announced at a meeting of East Isthmus residents tonight that it is proposing to permanently abandon Well No. 3 this summer. The well, located at the corner of First Street and East Johnson Street, has been shut down since September 2006 due to the presence of carbon tetrachloride in the water. The Utility has begun the process of finding a location for and developing a new well to replace Well No. 3.
Utility officials completed their review this week of an analysis and report submitted last week by Black & Veatch Corporation engineers, in which the Utility had asked for an evaluation of its ability to meet water demand, even under emergency conditions, with Well 3 out of service. Even though the Utility had no intention of operating Well 3 again, it wanted assurance before abandoning it that it would not need the well in the event of an emergency (fire protection, extreme drought, etc) before a replacement well is online. The Utility plans to have a replacement well online in 2012.
Water Utility General Manager David Denig-Chakroff said, "this report and the decision to move forward with Well 29 gives us confidence that our water system can respond to likely emergencies once we abandon Well 3, and gives residents the assurance we will never operate the well again."
The report looked at current water supply projections and capacity as well as for the years 2010 and 2015. The report's recommendations state, in part, "Because there is adequate capacity in the current and planned well supply, booster pumping, and emergency supply facilities to meet current and projected demands with [Well No. 3] out of service, the [utility] could abandon [Well No. 3] immediately and not be short of facility capacity."
Utility officials said that the results of this study in combination with the decision this week by the Board of Water Commissioners to proceed with installation of a filtration system at Well 29 provides assurances the water system can meet projected water demands without relying on Well 3 as an emergency backup well. Utility staff will present the report and its recommendations to the Madison Board of Water Commissioners on May 15, and will recommend to the Board that the Utility proceed with the process of abandoning the well immediately.
Utility Principal Engineer Al Larson said, "the analysis and report does not impact the decision to proceed with the development of a replacement well for Well 3. Long-term projected growth in water demand in the area and our need for system reliability and redundancy necessitate that we replace the well within five years."
Well No. 3 was drilled in 1928, and is the oldest well in the Madison water system. In recent years, the well has produced elevated levels of iron, manganese and carbon tetrachloride. Iron and manganese in the well resulted in complaints about discolored water at customers' taps.
Low levels of carbon tetrachloride, an industrial chemical used as a cleaning solvent and degreasing agent, have been detected in the well since the early 1990s and have increased gradually over the years. The federal regulatory standard for carbon tetrachloride in drinking water requires that the average of four consecutive samples from the well remain below 5 parts per billion (ppb). The Utility shut down Well 3 in September after a single sample exceeded 5 ppb. Since the average of the last four consecutive samples from the well was 3.73 ppb, the well did not exceed federal regulatory standards before it was taken out of service.
The utility is working closely with a formal group of residents of the area formerly served by Well 3, and local consultants Montgomery Associates to identify the most appropriate location for a new well. "We are using this as a new approach to siting wells in response to our customers' requests for involvement in major decisions that affect their homes and neighborhoods. We believe a collaborative process, coupled with solid technical and scientific examination will yield the best possible outcome," concluded Denig-Chakroff.
- David Denig-Chakroff266-4652
- Al Larson266-4653
- Joe Grande266-4654