WRM project to investigate groundwater recycling

May 27, 2011

Madison-area residents recycle plastics, cans, glass, paper and more. But one ubiquitous item is missing from the recycling program: water.

2011 WRM workshop students

The concept of water recycling, also known as water reuse, may strike some residents as unusual or unnecessary, but many communities across the country are implementing such programs. Sixteen students in the Nelson Institute's Water Resources Management (WRM) graduate program believe Madison, too, could benefit from a water recycling program--something they're exploring as part of a group research practicum this summer.

Each year, WRM students complete a summer workshop focused on a contemporary problem in water resources. The workshops, which have been conducted since the mid-1960s, bring together students with diverse backgrounds and areas of specialization to work as an interdisciplinary team and contribute to water resources policy. Participants devote much of the university summer session to the project after participating in a planning seminar the preceding spring semester.

Local problem

A water recycling program in the Madison area could help alleviate the area's groundwater depletion problems.

Local water utilities pump water for public supply from deep wells in aquifers--rock formations that hold significant volumes of water. Population growth has increased these water withdrawals and replenishment of the groundwater has not kept pace with demand. As a result, the water table has fallen significantly in some areas, leading to low flows in springs and streams and creating areas around the Yahara Lakes where the lakes are losing water to the ground. These conditions can threaten ecosystems in adjacent lands and limit recreational opportunities, such as boating, along the Yahara River.

In an effort to preserve local springs and streams and maintain sufficiently high flows in the Yahara, the WRM students are working with the Madison Metropolitan Sewerage District (MMSD) and the city of Fitchburg to explore the feasibility of implementing water recycling in the area.

The recycling program would use treated wastewater from MMSD's Nine Springs Wastewater Treatment Plant, which every day discharges 44 million gallons of treated wastewater to surface waters outside the Yahara watershed. Once outside the watershed, the treated wastewater cannot replenish the aquifers from which it was initially drawn. But a water recycling project could direct some of the water back to those aquifers.

Feasibility study

The students began their work during the 2010-2011 academic year with the guidance of program advisors Ken Potter, a professor of civil and environmental engineering, and Jean Bahr, a professor of geosciences--both affiliate faculty in the Nelson Institute.

Students studied the groundwater recharge process (in which rainwater percolates from the ground surface down to an aquifer) and researched how treated wastewater could be used as a water source to promote artificial recharge. They also investigated potential sites in Fitchburg where artificial recharge using treated wastewater could be implemented safely and effectively, then presented their plans and progress at public meetings in January and May.

Three sites in Fitchburg were selected for further investigation, where this summer students will conduct soil studies, water sampling, ecosystem assessments and other field tests. Those sites are the wetland around the Nine Springs E-way (an environmental corridor that extends approximately seven miles), the Wisconsin Department of Natural Resources hunting grounds and the Nine Springs Golf Course.

In late May, students worked with drilling technicians from the U.S. Geological Survey to characterize the soils and subsurface at the DNR hunting grounds site, using a Geoprobe to take samples (see a slideshow of photos below). Future field work will focus on water quality at the wetlands site.

The students aim to find ways to effectively replenish the aquifers while supporting the health of the environment and the human population. In September, students will present their conclusions and recommendations to MMSD and Fitchburg city planners to be considered for larger implementation.
Caitlin O'Connell is a master's candidate in the Nelson Institute's Water Resources Management program.