R2023-259 Resolution Authorizing Amendment No. 4 for Professional Engineering Services Agreement with Northwater Consulting for Lake Decatur Watershed Management Plan City Project 2019-38

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Lake Decatur Watershed Management Plan—Phase V Scope of Services& Budget o Water quality monitoring will continue in partnership with ISWS approximately bi-weekly at the three stations established in late 2019. Locations include, (i)Sangamon River IL 32, (ii) Friends Creek and (iii) Big/Long Creek. During larger storm events, attempts will be made to directly measure flows with acoustic doppler profiler methods to calibrate and maintain stage/discharge relationships. o Automatic water sampling equipment was installed at the 3 stations in Phase IV to better capture storm events. These samplers will be maintained and managed to capture 4-5 storm events per year during Phase V. Samples are submitted to the ISWS laboratory or RCPP partners(i.e., Decatur Sanitary District) for analysis. 2. Continuous Monitoring o Northwater will continue to support management of the automatic monitoring station on the Sangamon River at the IL 32 bridge. This is in partnership with the National Great Rivers Research and Education Center (NGRREC) and includes river stage, nitrate, turbidity, temperature/conductivity, dissolved oxygen and dissolved organic matter. The monitoring sensors, telemetry and solar power system was purchased under phase II and installation was completed in 2022. o On behalf of the City, Northwater will coordinate with NGRREC in the maintenance and operation of the system to minimize downtime. Data will be regularly checked with QA/QC procedures to make sure the station and sensors are in in working order and data quality is satisfactory. o BMP Monitoring sites ■ DeWitt Well Field — Baseline monitoring to characterize stormwater and drainage tile flows and sediment and nutrient concentrations. Northwater is in discussions with NGRRECto install automatic water sampling equipment in Phase V to better capture storm events. ■ The budget includes baseline monitoring at one additional BMP site to start in Phase V,which will be determined during Phase IV or early Phase V. 3. Data Management o Monitoring data will be managed and maintained in a relational database system using MS Access. A database architecture has been developed in coordination with the ISWS to make synthesizing data between organizations more efficient. o Northwater will utilize tools and processes for data validation and QA/QC of sensor data. o Online access to sensor and telemetry data will be maintained by Northwater, this includes all telemetry and server related-costs. o Managing and maintaining data will be an on-going and important part of the monitoring program. �'�"' n©rthwater