EPA 600/S-23/151 | October 2023 | www.epa.gov/research Real Time Storm Sewer Monitoring Joshua A. Steenbock U.S. Environmental Protection Agency Cincinnati, OH 45268 ------- Disclaimer The U.S. Environmental Protection Agency (EPA) through its Office of Research and Development funded and managed the research described herein under Task order 68HERC19D0009 Aptim Federal Services. It has been subjected to the Agency's review and has been approved for publication. Note that approval does not signify that the contents necessarily reflect the views of the Agency. Any mention of trade names, products, or services does not imply an endorsement by the U.S. Government or EPA. The EPA does not endorse any commercial products, services, or enterprises. Joshua Steenbock, M.S. U.S. Environmental Protection Agency Office of Research and Development Center for Environmental Solutions and Emergency Response 26 Martin Luther King Dr W Cincinnati, OH 45220 Phone 513.569.7204 1 ------- Foreword The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to formulate and implement actions leading to a compatible balance between human activities and the ability of natural systems to support and nurture life. To meet this mandate, EPA's research program is providing data and technical support for solving environmental problems today and building a science knowledge base necessary to manage our ecological resources wisely, understand how pollutants affect our health, and prevent or reduce environmental risks in the future. The Center for Environmental Solutions and Emergency Response (CESER) within the Office of Research and Development (ORD) conducts applied, stakeholder-driven research and provides responsive technical support to help solve the Nation's environmental challenges. The Center's research focuses on innovative approaches to address environmental challenges associated with the built environment. We develop technologies and decision-support tools to help safeguard public water systems and groundwater, guide sustainable materials management, remediate sites from traditional contamination sources and emerging environmental stressors, and address potential threats from terrorism and natural disasters. CESER collaborates with both public and private sector partners to foster technologies that improve the effectiveness and reduce the cost of compliance, while anticipating emerging problems. We provide technical support to EPA regions and programs, states, tribal nations, and federal partners, and serve as the interagency liaison for EPA in homeland security research and technology. The Center is a leader in providing scientific solutions to protect human health and the environment. Stormwater control has long been an area of concern, especially in areas that contain aging infrastructure and combined sewer systems. This report tested a novel biological water quality monitoring system in a stormwater sewer system located in Cincinnati, OH. Results were compared to data obtained via traditional grab sampling. The biological monitoring system was able to record and present data on microbial levels on a minute-to-minute basis from a website hosted by the manufacturer. Gregory Sayles, Director Center for Environmental Solutions and Emergency Response 2 ------- Table of Contents Disclaimer 1 Foreword 2 Abbreviations and Acronyms 4 List of Figures and Tables 4 Acknowledgments 5 Executive Summary 6 1.0 Background 7 Bechtold Park and Cooper Creek 7 2.0 SENTRY Biomonitoring System and VEGAPULS C 21 Level Sensor 8 3.0 QA/QC 9 4.0 Results 10 5.0 Discussion and Conclusions 12 6.0 References 14 3 ------- Abbreviations and Acronyms CCR Carbon-Consumption Rate CESER Center for Environmental Solutions and Emergency Response CFU Colony Forming Unit(s) CSO Combined Sewer Overflow CSS Combined Sewer System EPA U.S. Environmental Protection Agency IoT Internet of Things m Meter mg/L milligram(s) per Liter mm Millimeter NTU Nephelometric Turbidity Unit ORD Office of Research and Development TN Total Nitrogen TP Total phosphorus TSS Total Suspended Solids TDS Total Dissolved Solids I ist of Figures and Tables Figure 1. Water Basin of Bechtold Park Test Site StreamStats 2023 7 Figure 2. FABCO Stormwater Diversion Device 8 Figure 3. Upstream and Downstream Locations of the SENTRY System Sensors 9 Figure 4. Bechtold Park Water Levels 10 Figure 5. CCR results from SENTRY Biomonitoring device 11 Figure 6 Representative example of the relationship between water level and CCR 11 Table 1 Laboratory Analytical Techniques 10 Table 2 Influent and Effluent Sampling Results 12 4 ------- Acknowledgments Thank you to Jeff Szabo and Jim Goodrich for serving as reviewers for this Report. Thank you to Adam Lehman and the Hamilton County Conservation district for all the insight and help facilitating this project. 5 ------- Executive Summary This report summarizes efforts to detect contamination from rainfall events using online water quality sensors. Stormwater has long been an area of concern when it comes to contaminant monitoring and potential remediation. Combined Sewer Overflow (CSO) systems can collect rainwater and sanitary sewage, but heavy rainfall can overwhelm the treatment system and allow untreated stormwater and wastewater back into local streams and waterways, in the form of a CSO. Using online water quality sensors can allow researchers and water treatment officials to observe local waterways for potential CSOs in real time and provide warnings to the local population or install mitigation technology at the area of concern. This project took place at Cooper Creek in Bechtold Park located in Cincinnati, OH. The park is characterized by a mix of residential and commercial areas. Within the project site, a stormwater retrofit device was installed and packed with various media to test the efficacy of the water treatment materials. Bacteria levels were measured using a SENTRY real-time bacterial monitoring sensor (SENTRY™ Water Technologies, Inc., 65 Watts Avenue, Charlottetown, PE C1E 2B7, Canada). Flow levels were recorded via a VEGAPULS C 21 (VEGA AMERICAS, Inc., 3877 Mason Research Pkwy., Mason, OH 45036 U.S.). The VEGAPULS is a noncontact level sensor with a measuring range of up to 15 m (meters) and is accurate to within ±2 mm (millimeters). The biological monitoring system was able to record and present data on microbial levels on a minute-to- minute basis from a website hosted by the manufacturer. When comparing bacterial spikes to water levels recorded via the level sensor, the data suggest that stormwater discharges are not the sole contributor to higher coliform counts. The SENTRY system demonstrated its ability to monitor data remotely and remain functional while being submerged within a stream for an extended period. 6 ------- 1.0 Background Stormwater control has long been an area of concern, especially in areas that contain aging infrastructure and combined sewer systems. As a part of current research efforts, novel water quality sensors are being tested to see how they might assist researchers in identifying and mitigating potential contamination from stormwater. Nearly 80% of pollutants, biological or chemical, are found within the first flush of stormwater following precipitation events (Jean-Luc Bertrand-Krajewski, 1998) (Szabo, Buchberger, & Bishop, 2005). Finding a way to measure contamination from stormwater is an important first step in mitigating its effects. Bechtold Park and Cooper Creek Bechtold Park is located within Cincinnati, OH, and is used for a variety of recreational purposes. Cooper Creek is approximately 4 miles long and flows into Mill Creek, which connects to the Ohio River. The Cooper Creek watershed is 0.24 sq mi and characterized as a highly urbanized area (50% impervious) with commercial and industrial land use in the northeast corner and residential land use everywhere else (Fig. 1) Through a partnership with the Hamilton County Soil & Water Conservation District and the Cooper Creek Collaborative, it has been the site of several EPA projects. Various stormwater controls have been installed in Cooper Creek, and this same site served as the project location for this study. The Cooper Creek Collaborative has confirmed two CSOs near Cooper Creek, represented by red circles on Figure 1. One CSO is near the watershed's outlet and the other is just downstream of the confluence with Mill Creek Figure 1. Water Basin of Bechtold Park Test Site StreamStats 2023 On August 2019, the FABCO passive flow management device (FABCO Industries, 24 Central Drive, Farmingdale, NY 11735) was installed along Cooper Creek, represented by a black star on Figure I., The FABCO device is a water diversion structure that allowed for different contaminant-absorbing media to 7 ------- be installed (Fig. 2). Along with the FABCO, a dam was installed to limit the flow of water and ensure that any water passed through the media FABCO Fabguard, a proprietary stormwater media, was installed inside the FABCO device to serve as a filter media to reduce colifonn numbers. Although reducing the colifonn counts is not the focus of this report, it does serve to help quantify the health of the stream (EPA, 2023). Figure 2. FABCO Stormwater Diversion Device 2.0 SENTRY Biomonitoring System and VEGAPULS C 21 Level Sensor As a part of an overarching goal to monitor and treat urban/residential contamination within stormwater, a novel water quality sensor containing IoT (Internet of Tilings) technology was installed within the Bechtold Park project site. The SENTRY system works by using a bioelectrode to measure the Carbon- Consumption Rate (CCR) of the microbes in the water source. Biofilm is grown on the surface of the sensor to which a constant voltage is applied. As the biofilm oxidizes the organic matter and uses energy, the induced current will change (Sentry Water Tech - Clean Water Applications). This current is measured and converted into a CCR measurement that is ultimately reported back to a real time graph that is displayed via the SENTRY Biomonitoring website. As a part of the installation at Bechtold Park, two CCR sensors and a data management panel were installed alongside the FABCO unit on June 24, 2020, and remained in place until October 24, 2021. Sensor EPA01 was installed upstream of the FABCO dam and Sensor EPA02 was installed downstream of the dam (Fig. 3). Both EPA01 and EPA02 are distinct sensor units that report back to one SENTRY unit. The sensors' positions were switched on August 12, 2021, to rule out any biases that the individual sensors may have been exhibiting. Readings were taken every minute during the deployment. 8 ------- Figure 3. Upstream and Downstream Locations of the SENTRY System Sensors The VEGAPULS C 21 radar sensor (VEGA) was installed behind the diversion device in August 2019. The VEGA is a noncontact level sensor with well documented ability to measure flow in open-channel waterways. Data from this device were collected via the NEXSENS data collection system (NexSens Technology, Inc., Fairborn, OH 45324) and displayed via iChart. Level data was compared to microbial readings to determine if there was a correlation between increased rainfall and higher CCR levels. 3.0 QA/QC The objective of this report is to compare measurements obtained by novel IoT water quality technology to measurements obtained via traditional industry standard technology. CCR data obtained from the SENTR Y system were compared to a grab sample obtained from both upstream and downstream of the FABCO unit on 7/27/2021. Grab samples were obtained by hand and were refrigerated until analysis could be performed. Protocols for analyses done on grab samples are outlined in the table below. Parameter Instrument or Procedure Analytical Method Total Nitrogen (TN) Spectrophotometer (Hach DR6000, Loveland, CO) Hach Method 10208 Total Phosphorus (TP) Spectrophotometer (Hach DR6000, Loveland, CO) Hach Method 10210 Total Suspended Solids (TSS) Dry/Weigh Standard Methods for the Examination of Water and Wastewater-2540 SOLIDS Total Dissolved Solids (TDS) F i Iter/'Dry/'Weigh Standard Methods for the Examination of Water and Wastewater-2540 SOLIDS 9 ------- E. coli IDEXX (Westbrook, ME) Standard Methods for the Examination of Water and Wastewater-9223 ENZYME SUBSTRATE COLIFORM TEST Turbidity Turbidimeter (Hach 2100, Loveland, CO) Standard Methods for the Examination of Water and Wastewater - 2130 TURBIDITY Table 1 Laboratory Analytical Techniques The IoT devices installed at the project site were able to upload data to an external cloud that could be accessed by EPA researchers in real time. Comparing data obtained via the SENTRY system to grab samples collected and tested via traditional means can identify potential connections between E. coli levels and CCR readings. 4.0 Results Both the VEGA level sensor and SENTRY system performed with minimal interruptions for the duration of the study. The battery on the SENTRY died 7/25/21 but was replaced the next day, and no performance issues were observed. No other maintenance was needed for either device. Water levels increased at the Bechtold park site during local precipitation events except for four events that showed an increase in water level with no corresponding precipitation event (see arrows below in Fig. 4). NEXSENS tech notogy Data Graph Bechtold Park Water Level Data 7/22/21 8/21/21 9/20/21 10/20/21 00:00 00:00 00:00 00:00 Date Water level, ft Figure 4. Bechtold Park Water Levels 10 ------- SENTRY data show an increase in CCR corresponding to increases in water levels, meaning there are elevated bacteria levels every time there is a discharge into the creek, whether it be from stormwater or another source. The CCR was higher on the upstream portion of the dam starting approximately July 20, running contrary to expected results of lower microbial activity from the FABCO water diversion device. On August 12 (green arrow), the probes were switched to rule out any potential bias or malfunctioning. The results remained the same with the upstream sensor, CCR EPA02, reading higher than the downstream sensor (Fig. 5). EPA01 upstream EPA02 downstream 12 Aug. Probes were swapped A EPAQ1 downstream EPA02 upstream -CCR EPA02 -CCREPA01 t- - nM 1 ^ , .<*¦ - Figure 5. CCR Results from SENTRY Biomonitoring Device. Probes Were Switched on Aug. 12, Indicated with a Green Arrow Figure 6 plots both the CCR levels from sensor EPA01 and the water levels from a representative rain event on 6/30/2021. As the water level increased throughout the beginning of the rain event, CCR increased as well until the initial microbial load had passed the sensor. CCR and Water Level 180 160 140 120 oe 100 u u 80 60 40 20 3.5 3 2.5 2 1.5 1 0.5 0 0 6/30/2021 16:486/30/2021 18:006/30/2021 19:126/30/2021 20:246/30/2021 21:366/30/2021 22:48 7/1/2021 0:00 7/1/2021 1:12 Axis Title CCR •Water Level Figure 6 Representative Example of the Relationship Between Water Level and CCR 11 ------- A grab sample was taken on 7/27/2021 on either side of the FABCO dam, obtaining both influent and effluent water quality from the FABCO (Table 1). While the E. coli data cannot be compared directly with CCR data, it is a good indication of the number of bacteria on either side. E. coli levels were 5.49 x 104 CFU/100 mL on the upstream/influent side of the dam, and at the time of sampling the SENTRY reported a CCR level of 73.55. On the downstream/effluent side of the dam, the E. coli levels were 2.13 x 104 CFU/100 mL, and during sampling the SENTRY reported a CCR reading of 33.67. Sample Date 7/27/2021 ANALYSIS UNITS 9:15 9:18 Turbidity NTU 4.33 4.05 Escherichia coli (E. coli) CFU/100 mL 5.49 x 104 2.13 x 104 Total Suspended Solids (TSS) mg/L 4 4 Total Dissolved Solids (TDS) mg/L 666 567 Total Nitrogen (TN) mg/L 8.16 6.09 Total Phosphorus (TP) (PO43) mg/L 0.845 0.693 Orthophosphate (PO43 P) mg/L 0.276 0.226 Table 2 Influent and Effluent Sampling Results 5.0 Discussion and Conclusions The SENTRY System was generally helpful in monitoring the microbial activity in Cooper Creek. The sensor remained functional throughout the life of the study and transmitted data with no mechanical errors. The only interruption was a result of human error: not replacing a dying battery in time. Data show that CCR levels were higher on the sensor upstream of the FABCO stormwater diversion device for multiple data points, but this may be due to the location of the sensor rather than the efficacy of the FABCO. In Figure 3, sensor EPA02 was placed directly on the downstream side of the dam rather than at the end of the outflow pipe, which could have resulted in water backflowing and sitting stagnant, allowing bacteria levels to build back up. When comparing the CCR data to data obtained via a grab sample, there are higher CCR values and E. coli concentrations upstream than downstream. The microbial activity associated with CCR cannot be explicitly explained by E. coli levels, but the potential for a correlation exists. However, more samples would need to be taken to establish such a relationship. These data help support the efficacy of the SENTRY system. Most of the observed water level increases correspond to rainfall events in the area. However, there are several instances that the water levels increased during dry periods and may indicate unregulated releases into Cooper Creek. On September 13, water levels rose while the CCR levels dropped to zero and remained there for several days, pointing to some sort of discharge that inhibited microbial growth into the stream. The increase in discharge may be due to effluent from a local swimming pool. At the end of the season, the pool filters were backwashed, and the effluent discharged into Cooper Creek that morning. 12 ------- Future research could include new sites, potentially in unmodified waterways, and more consistent collection of grab samples so that the SENTRY results can be better compared to more traditional methods of water quality analysis. The methods established here can be reproduced in any watershed potentially allowing for real time monitoring and control for elicit discharges during dry weather and CSOs during wet weather. Understanding microbial activity in real time can better inform operation and maintenance of storm water facilities. 13 ------- 6.0 References EPA. (2023). Revised Total Coliform Rule. Retrieved from epa.gov: https://www.epa.gov/dwreginfo/revised-total-coliform-rule-and-total-coliform-rule Jean-Luc Bertrand-Krajewski, G. C. (1998). Distribution of pollutant mass vs volume in stormwater discharges and the first flush phenomenon. Water Research, 2341-2356. Performance of Wet Weather Treatment Facility for Control of Combined Sewer Overflows: Case Study in Cincinnati, Ohio. (n.d.). Sentry Water Tech - Clean Water Applications. (2023, March 1). Retrieved from Sentry Water Tech: https://www.sentrvwatertech.com/energy-optimization/clean-water-applications Szabo, J., Buchberger, S., & Bishop, P. (2005). Performance of Wet Weather Treatment Facility for Control of Combined Sewer Overflows: Case Study in Cincinnati, Ohio. Journal of Environmental Engineering, 131. 14 ------- |