Madison advances new biosolids database to address testing latency after CMAR grade drop

Madison advances new biosolids database to address testing latency after CMAR grade dropThe Madison Metropolitan Sewerage District is revamping its biosolids data management after delayed nitrogen test results led to a 'D' grade in its 2025 Compliance Maintenance Annual Report.

The district achieved a 3.59 overall GPA on its 2025 CMAR, scoring 'A' grades in all categories except Biosolids Quality and Management.

The 'D' grade resulted from nitrogen over-application on just two out of 327 farm fields, caused by a one- to two-week latency in laboratory test results.

To address the issue, staff are developing a new database to streamline quality assurance checks and connect truck loads to application fields more efficiently.

The CMAR also detailed corrective actions for three sanitary sewer overflows and six treatment facility overflows in 2025, including the permanent repair of a 36-inch force main.

The Madison Metropolitan Sewerage District (MMSD) is taking steps to refine its biosolids data management after minor nitrogen over-applications impacted its 2025 Compliance Maintenance Annual Report (CMAR). During the June 11, 2026, commission meeting, staff presented the 2025 CMAR, noting a high overall GPA of 3.59. The district scored 'A' grades in influent flow, effluent quality, staffing, and financial management. However, it received a 'D' in Biosolids Quality and Management. Process and Regulatory Performance Engineer Jacob Kositzke explained that the biosolids section is graded on a strict curve, where a single instance of nitrogen over-application results in an automatic 'D' score regardless of the quantity. The over-application occurred on just two of the 327 farm fields utilized by the district's Metrogro program, which land-applied 39.7 million gallons of biosolids across 7,363 acres in 2025. Biosolids Specialist Zac Thompson detailed that the district relies on the average of its three most recent nitrogen data points to determine agronomic application rates. Because there is a one- to two-week turnaround for laboratory results, the actual nitrogen content at the time of application can sometimes slightly exceed the calculated average. On the two fields in question, the nitrogen content came back 5% to 7% higher than anticipated, consuming the district's built-in 10-pound buffer and pushing the application slightly over the recommended limit. To prevent future occurrences, MMSD is flagging the two affected fields to prevent further application for a minimum of two crop years. Additionally, the district is developing a new database to fix data management challenges. Thompson noted the system will calculate application rates faster and ensure truck loads and fields are properly connected within the database structure. The district is also researching new technologies currently used in dairy manure application that might increase the speed of biosolids test results. The commission formally accepted the CMAR, which also outlined responses to three sanitary sewer overflows (SSOs) and six treatment facility overflows (TFOs) in 2025. Notably, a major SSO in August 2025 involving the failure of a 36-inch force main resulted in a 6-million-gallon spill. The district has since completed permanent repairs on the line and reinforced procedures related to bypass pumping and digester maintenance.