UNH Stormwater Center's Continuous Monitoring Practices in RWP

PC: Ryan Kopp. Pictures of UNH Stormwater Center and Audubon Society of Rhode Island team members during an equipment installation day.

By: Casey Chan

The University of New Hampshire (UNH) Stormwater Center is an integral partner in the continuous/real time monitoring of water quality in Roger Williams Park. The team at UNH has guided the Providence Stormwater Innovation Center by introducing methods of monitoring and assessing water quality data such as phosphorus and dissolved oxygen concentrations, temperature, and water quantity/flow. The UNH team is also a member of the SNEP Network, and has specialized equipment and testing experience that is necessary for the Center's water quality measurements.

The SNEP Network will use the projects in Roger Williams Park to create a curriculum for teaching others about stormwater management. These projects will act as a physical learning resource for surrounding communities. The knowledge gained from PSIC's projects, including lessons learned, will be shared with different organizations involved in stormwater infrastructure.

Today, we had an opportunity to interview Elizabeth Buschert from the UNH Stormwater Center, who is contributing to the monitoring efforts in Roger Williams Park. She provided us with details about her team's monitoring processes, and what trends we may be looking for in the collected data. She also gave us suggestions for displaying collected continuous data in the Seal House and beyond.

According to Buschert, the UNH team will be using UV-Vis spectrolysers and YSI scans to measure data at the inflow and outflow of the park’s ponds. The UV-Vis spectrolysers can measure total suspended solids, nitrate, and total phosphorus concentrations. YSI sensors can measure oxygen concentrations, temperature, and pH. Onset HOBO water level loggers are also placed into the ponds to determine water levels. These continuous sensors will be used in conjunction with grab samples collected by volunteers and photos taken by the park’s visitors at Picture Posts.

PC: Ryan Kopp A UV-Vis Spectrolyser

Currently, the inflow monitor is near the Seal House in Roger Williams Park, and the outflow sensor is located closer to the outflow of the Roger Williams Park watershed. One piece of data that can be collected at the inflow and outflow of the park watershed is water level. The water level sensor has already been installed, and water level data can be converted into water flow data using a mathematical relationship. Water flow is necessary to show how much water arrives from other watersheds and leaves the park. It can also be combined with nutrient level data to determine the nitrogen and phosphorous flux into and out of the park. COVID-19 restrictions have caused a slight delay in further installations, but all of the real-time monitoring devices will be fully installed in the coming month.

Since stormwater conditions can change from year to year, it may be difficult to compare yearly data to determine the effects of BMP installation. However, continuous data can help us to understand how individual storms or seasonal conditions affect water quality.

Continuous data also allows us to determine whether the stormwater structures are functioning as intended. Since the BMPs are implemented based on theoretical models, it is helpful to monitor the functioning of the BMPs in real time.

PC: Elizabeth Buschert. HOBO loggers installed near a BMP. The loggers are placed on each side of the stone weir structure and down the monitoring well. The monitoring well is the gray pipe that is located halfway along the grassy bank behind the weir structure in the second picture.

So far, three BMPs have monitors that measure the amount of water infiltrating each BMP. It is assumed that the water that infiltrates into the stormwater structure has been purified, as compared to unfiltered stormwater. Water quality data cannot be collected directly from the BMP structure runoff, because most of the water infiltrated through the BMP soaks into the soil. Instead, the measured infiltrated water level can be applied to mathematical EPA models that differ based on the type, size, and shape of the BMP. This information is used to estimate the amount of pollutants removed by each BMP.

The current issue with obtaining data from the ponds is that parts of the park have not been constructed to accommodate effective and stable measurement. The UNH team will be working to install measuring devices near structures that were not engineered for this use. They are also determining the best ways to display the collected data, for example by projecting it directly onto a monitor. It may also be possible to duplicate the data using a graphing program and display it in a kiosk.

If pond water quality remains poor after the BMP installations, it may be possible that pollutant concentrations originate from areas outside of the park watershed. An upper watershed consisting of the Mashapaug, Tongue, and Spectacle ponds feeds into the Roger Williams Park watershed, and may be the source of phosphorus and sediment contamination.

PC: Ryan Kopp Installation Mat

PC Ryan Kopp. Left: Installation Materials. Right: View of installation from the water.

There are many ways for surrounding communities to improve stormwater quality. As Buschert states, the more water you stop from entering into the watershed, the more pollution you can prevent. Local homeowners and residents can help to reduce the amount of potentially polluted stormwater flowing into the park watershed. Some examples of residential efforts could be to use a rain barrel or to point a downspout towards a lawn instead of a driveway. This practice can make an important difference, because it causes stormwater to be reabsorbed into the soil, instead of flowing over impervious surfaces and bringing pollutants into the park ponds. Thank you to Elizabeth Buschert and the UNH Stormwater Center team for their monitoring efforts in Roger Williams Park!