Browsing by Author "Weiss, Peter T."

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Assessing and Improving Pollution Prevention by Swales
(St. Anthony Falls Laboratory, 2014-08) Gulliver, John S.; Ahmed, Farzana; Natarajan, Poornima; Weiss, Peter T.; Nieber, John L.
Roadside swales are drainage ditches that also treat runoff to improve water quality, including infiltration of water to reduce pollutant load. In the infiltration study, a quick and simple device, the Modified Philip Dunne (MPD) infiltrometer, was utilized to measure an important infiltration parameter (saturated hydraulic conductivity, Ksat) at multiple locations in a number of swales. The study showed that the spatial variability in the swale infiltration rate was substantial, requiring 20 or more measurements along the highway to get a good estimate of the mean swale infiltration rate. This study also developed a ditch check filtration system that can be installed in swales to provide significant treatment of dissolved heavy metals and dissolved phosphorous in stormwater runoff. The results were utilized to develop design guidelines and recommendations, including sizing and treatment criteria for optimal performance of the full-scale design of these filters. Finally, the best available knowledge on swale maintenance was combined with information obtained from new surveys conducted to develop recommendations for swale maintenance schedules and effort. The recommendations aim toward optimizing the cost-effectiveness of roadside swales and thus provide useful information to managers and practitioners of roadways. The research results and information obtained from this study can thus be used to design swale systems for use along linear roadway projects that will receive pollution prevention credits for infiltration. This will enable the utilization of drainage ditches to their full pollution prevention potential, before building other more expensive stormwater treatment practices throughout Minnesota and the United States.
Assessing and Improving Pollution Prevention by Swales
(Center for Transportation Studies, University of Minnesota, 2014-08) Ahmed, Farzana; Natarajan, Poornima; Gulliver, John S.; Weiss, Peter T.; Nieber, John L.
Roadside swales are drainage ditches that also treat runoff to improve water quality, including infiltration of water to reduce pollutant load. In the infiltration study, a quick and simple device, the Modified Philip Dunne (MPD) infiltrometer, was utilized to measure an important infiltration parameter (saturated hydraulic conductivity, Ksat) at multiple locations in a number of swales. The study showed that the spatial variability in the swale infiltration rate was substantial, requiring 20 or more measurements along the highway to get a good estimate of the mean swale infiltration rate. This study also developed a ditch check filtration system that can be installed in swales to provide significant treatment of dissolved heavy metals and dissolved phosphorous in stormwater runoff. The results were utilized to develop design guidelines and recommendations, including sizing and treatment criteria for optimal performance of the full-scale design of these filters. Finally, the best available knowledge on swale maintenance was combined with information obtained from new surveys conducted to develop recommendations for swale maintenance schedules and effort. The recommendations aim toward optimizing the cost-effectiveness of roadside swales and thus provide useful information to managers and practitioners of roadways. The research results and information obtained from this study can thus be used to design swale systems for use along linear roadway projects that will receive pollution prevention credits for infiltration. This will enable the utilization of drainage ditches to their full pollution prevention potential, before building other more expensive stormwater treatment practices throughout Minnesota and the United States.
Characterization of Runoff Quality from Paved Low-Volume Roads and Optimization of Treatment Methods
(Minnesota Department of Transportation, 2020-09) Natarajan, Poornima; Weiss, Peter T.; Gulliver, John S.
Vehicular traffic contributes a large fraction of the pollutant load in stormwater runoff from roadways. While runoff concentrations have historically been characterized for urban roads with high average daily traffic (ADT), the runoff quality from paved rural roads that have relatively low ADT is largely unknown. In this study, runoff from low-volume roads (ADT < 1500) in Minnesota was monitored at 10 locations during 174 rainfall events in 2018 and 2019. The initial concentrations of total suspended solids (TSS), total phosphorus (TP), nitrate+nitrite, and heavy metals in the runoff, and the relationship between measured concentrations and site-specific conditions were analyzed. Concentrations were strongly influenced by the surrounding land use and soil type. Sites with agricultural lands had higher mean TSS, TP, and zinc concentrations, and lower nitrite+nitrate concentrations than wooded sites, which can be related to the type of soil that would get transported onto the roadways. When compared to existing urban runoff quality data, the estimated event mean concentrations (EMCs) in rural road runoff were substantially lower for copper and zinc and marginally lower for TSS, TP and nitrate+nitrite. Based on detailed cost-benefit analysis of various roadside treatment options, roadside drainage ditches/swales are recommended for cost-effective treatment of runoff from low-volume roads over ponds, sand filters and infiltration basins. Example road widening projects were also modeled to determine how stormwater management requirements can be achieved using drainage ditches/swales.
Characterization of Runoff Quality from Paved Low-Volume Roads and Optimization of Treatment Methods
(2020-09) Gulliver, John S.; Natarajan, Poornima; Weiss, Peter T.
Vehicular traffic contributes a large fraction of the pollutant load in stormwater runoff from roadways. While runoff concentrations have historically been characterized for urban roads with high average daily traffic (ADT), the runoff quality from paved rural roads that have relatively low ADT is largely unknown. In this study, runoff from low-volume roads (ADT < 1500) in Minnesota was monitored at 10 locations during 174 rainfall events in 2018 and 2019. The initial concentrations of total suspended solids (TSS), total phosphorus (TP), nitrate+nitrite, and heavy metals in the runoff, and the relationship between measured concentrations and site-specific conditions were analyzed. Concentrations were strongly influenced by the surrounding land use and soil type. Sites with agricultural lands had higher mean TSS, TP, and zinc concentrations, and lower nitrite+nitrate concentrations than wooded sites, which can be related to the type of soil that would get transported onto the roadways. When compared to existing urban runoff quality data, the estimated event mean concentrations (EMCs) in rural road runoff were substantially lower for copper and zinc and marginally lower for TSS, TP and nitrate+nitrite. Based on detailed cost-benefit analysis of various roadside treatment options, roadside drainage ditches/swales are recommended for cost-effective treatment of runoff from low-volume roads over ponds, sand filters and infiltration basins. Example road widening projects were also modeled to determine how stormwater management requirements can be achieved using drainage ditches/swales.
Climate Change Adaptation of Urban Stormwater Infrastructure
(Minnesota Department of Transportation, 2023-06) Erickson, Andrew J.; Herb, William R.; Gallagher, Noah D.; Weiss, Peter T.; Wilson, Bruce N.; Gulliver, John S.
The final analysis of historical (TP-40), current (Atlas 14), and future predicted storm events for three watersheds in Minnesota (Duluth, Minneapolis, Rochester) has shown that current design philosophy is not sufficient to prevent flooding from 10-year and larger design storm events and that flood depth and duration will increase given current climate projections. Several stormwater infrastructure adaptation strategies were assessed for reducing flood depth and duration: Baseline (existing conditions), adding rain gardens (aka, Infiltration Basins), adding new wet ponds, retrofitting existing stormwater ponds to be ?Smart Ponds, adding new Smart Ponds while also converting existing ponds into Smart Ponds, or upsizing of stormwater pipes to convey more water. In watersheds that are mixed urban, suburban, and rural like Rochester?s Kings Run or Duluth?s Miller Creek sub-watersheds, the most cost-effective climate change adaptation strategy was to build new stormwater wet ponds (Extra Ponds strategy) to treat the impervious surfaces not currently treated by existing wet ponds and other stormwater BMPs. In the fully developed urban 1NE watershed in Minneapolis, the most cost-effective (excluding land costs) climate change adaptation strategy was building wet ponds (Extra Ponds). Securing property for building new stormwater infrastructure in fully developed urban watersheds like 1NE may be a substantial cost compared to other watersheds. Smart Ponds do not require additional land for implementation and thus represent a relatively low-cost alternative that will be more beneficial in watersheds with numerous existing wet ponds.
Compost use in Post-Construction Stormwater Practices: A Systematic Review & Results from Listening Sessions
(St. Anthony Falls Laboratory, 2023-11-01) Erickson, Andrew J.; Weiss, Peter T.; Wang, Zihang; Arnold, William A.; Kocher, Megan; Lafferty, Meghan
The Compost Research and Education Foundation (CREF) and the University of Minnesota (U of M) embarked on research to better understand the best uses of compost in stormwater bioretention media and identify compost characteristics that are most impactful to the success of these systems. It is critical for manufacturers, specifiers, end users, and regulators to understand these best uses so users can understand what performs well, suppliers can make a high-quality compost product, and designers can specify and receive a product best suited for the application. This will improve bioretention performance and confidence from specifiers and end-users, minimize pollution potential, and ultimately increase acceptance and use of compost in critical green infrastructure stormwater best management practices.
Contamination of Soil and Groundwater Due to Stormwater Infiltration Practices, A Literature Review
(St. Anthony Falls Laboratory, 2008-06-23) Weiss, Peter T.; LeFevre, Greg; Gulliver, John S.
Recently, there has been an increased interest in the use of infiltration as a method of managing stormwater. Infiltration practices promote groundwater recharge, reduce runoff peak flows and volumes, and can lessen the transport of non-point source pollutants to surface water bodies. However, because stormwater infiltration systems are designed to discharge runoff into the soil, there has been concern that pollutants present in stormwater could contaminate groundwater wells. Thus, to understand the relative risks and benefits of infiltration, the fate of stormwater pollutants must be well understood. The fate of contaminants infiltrated from stormwater runoff and the potential for groundwater contamination was investigated by reviewing literature published in peer-reviewed scientific and engineering journals. This review examines common stormwater infiltration techniques, priority pollutants in urban stormwater runoff, and investigates the fate of these pollutants after infiltration. Priority pollutants in urban stormwater runoff include nutrients (i.e. nitrogen and phosphorus), heavy metals (i.e. Pb, Zn, Cu, Cd), organics (e.g. petroleum hydrocarbons), pathogens, suspended solids, and salts. The potential for groundwater contamination is a complex function of soil and contaminant properties and the depth to the water table. Karst geology in particular can provide pathways for rapid and extensive groundwater contamination from infiltration systems.
The Cost and Effectiveness of Stormwater Management Practices Final Report
(St. Anthony Falls Laboratory, 2005-06) Weiss, Peter T.; Gulliver, John S.; Erickson, Andrew J.
With the implementation of the United States Environmental Protection Agency’s (USEPA) National Pollution Discharge Elimination Systems (NPDES) Phase I and II programs, strong interest has developed in the area of water quality treatment of stormwater runoff. While little is known about the cost effectiveness of available stormwater treatment technologies, called Stormwater Management Practices (SMPs) in this report, municipal agencies are now, or soon will be, required to meet certain pollutant removal criteria based on the Phase I and II regulations. Of primary concern are nutrients such as phosphorus (P) and nitrogen (N), which are just one of the pollutant categories being targeted for removal from stormwater runoff. Excess nutrients can initiate large algae blooms that generate negative aesthetic and eutrophic conditions in receiving lakes and rivers (USEPA, 1999a). In inland water bodies phosphorus is typically the limiting nutrient (Schindler, 1977) and can be contributed to stormwater from various sources such as fertilizers, leaves, grass clippings, etc. (USEPA, 1999a). Another pollutant of primary concern in stormwater is dirt, sand, and other solid particles which are commonly quantified by measuring the Total Suspended Solids (TSS) of a water sample. TSS can severely and negatively impact an aquatic environment. The solids increase turbidity, inhibit plant growth and diversity, affect river biota and reduce the number of aquatic species (Shammaa et al., 2002). Also, organic suspended solids can be biologically degraded by microorganisms in a process which consumes oxygen, which is important to the aquatic biota.
Design and Construction of Infiltration Facilities
(Minnesota Department of Transportation, 2021-06) Tecca, Nicholas P.; Gulliver, John S.; Nieber, John L.; Weiss, Peter T.
Infiltration stormwater control measures are an important structural practice to mitigate the impacts of urbanization on stormwater quality and quantity. Infiltration stormwater control measures help to mimic the natural processes of infiltration and evapotranspiration. Unfortunately, the failure rate of infiltration stormwater control measures has been observed to be between 10% and 50%. Two common causes of failure are addressed in this work, namely improper siting and improper characterization of saturated hydraulic conductivity. A procedure to calculate a preliminary infiltration rating (PIR) was developed in a geographic information system to identify areas where infiltration stormwater control measures are likely to be successful. The Modified Philip-Dunne infiltrometer, double ring infiltrometer, Turf-Tec IN2-W infiltrometer, and soil texture analysis were used to estimate infiltration capacity in three swales in the Twin Cities Metropolitan area. A correction factor was proposed for the Turf-Tec IN2-W infiltrometer. A protocol for assessing infiltration capacity was also proposed.
Enhanced Filter Media for Removal of Dissolved Contaminants from Stormwater
(St. Anthony Falls Laboratory, 2014-09) Erickson, Andrew J.; Gulliver, John S.; Weiss, Peter T.; Arnold, William A.
This report is the culmination of a 3-year research project titled, "Aqueous pollutant capture by enhanced filter media," which was funded by the Minnesota Pollution Control Agency through its Federal Clean Water Act Section 319 (Section 319) grant program, with Gregory Johnson as project manager. The purpose of this project was to research materials that could be used in new or renovated sand filters, infiltration systems, rain gardens, and buffer strips to capture significant amounts of dissolved heavy metals, phosphorus, and nitrogen that are typically found in urban and agricultural runoff. This was accomplished with five primary objectives, which have been organized into five representative Chapters that are described below. Chapter 1 consists of an extensive literature review that was used to not only inform and guide the project, but also to satisfy the first objective (Objective 1: Literature review and agent section). Through this literature review, enhancing materials were evaluated and some were selected for testing as part of this project. In addition, this literature prevented duplication of previous research efforts. The review incorporated performance by existing stormwater treatment practices for water quantity reduction and capture of dissolved heavy metals, phosphorous, and nitrogen and also investigated potential enhancements that capture dissolved heavy metals, phosphorus, and nitrogen. Chapter 2 discusses batch studies that were performed on enhancing materials selected in Chapter 1, which satisfies the second objective (Objective 2: Perform batch studies and agent selection). Batch studies involved mixing enhancing materials with synthetic stormwater laden with stormwater pollutants of concern: metals, phosphorus, and nitrogen. By collecting samples and measuring change in concentration, the sorption capacity of the enhancing materials was determined and compared for well-mixed conditions. From this comparison, several materials were selected to further investigation. Chapter 3 discusses column studies that were performed on a few enhancing materials selected from the literature review and batch studies, which satisfies the third objective (Objective 3. Perform column studies and develop descriptive models). Synthetic stormwater was added to these columns while samples were collected samples and flow rate was measured and controlled. Sorption capacity for flow-through conditions was estimated from the data collected. The Thomas model (Thomas 1948) is a well-known model in the chemistry field that describes breakthrough of pollutants in flow-through columns. When fit to the data collected in this project, the Thomas model was found to adequately describe the removal of pollutants by the enhancing materials selected. Chapter 4 discusses field verification studies that were performed on two enhancing materials, which satisfies the fourth objective (Objective 4. Field verification studies). River water was collected in lieu of natural stormwater and passed through a scaled enhanced media filter. The water was tested and supplemented as necessary to represent the target conditions for the experiment. Samples were collected and flow rate was measured to determine the sorption capacity that could be expected of the enhancing materials in a field application. Again, the Thomas model was fit to the data and found to adequately describe the removal of pollutants by the enhancing materials. Chapter 5 provides a summary of the project results and associated conclusions, which in addition to activities throughout the project, satisfies the fifth and final objective (Objective 5. Public Outreach/Public Participation and Deliverables).
Environmental Impacts of Potassium Acetate as a Road Salt Alternative (University of Minnesota evaluation)
(Minnesota Department of Transportation, 2022-07) Gulliver, John S.; Chun, Chan Lan; Weiss, Peter T.; Erickson, Andrew J.; Herb, William; Henneck, Jerry; Cassidy, Kathryn
Road salt (NaCl) is used predominantly across the state for winter road anti-icing (as brine) and de-icing (as a solid) operations. Road salt is used because it is inexpensive and effective, but the thousands of tons used annually have resulted in increasing chloride concentrations of surface water bodies throughout Minnesota. In many cases, chloride concentrations are above regulatory limits, which results in the loss of aquatic biota and the water body being labeled as impaired. Thus, there is a need for one or more road salt alternatives (RSAs) that are effective, relatively inexpensive, and environmentally friendly. This report investigates the environmental impacts of potassium acetate (Kac), which is effective at lower temperatures than most other potential RSAs and is also less corrosive to steel than conventional road salt. Field measurements indicate that current applications of KAc do not have a substantial influence on biochemical oxygen demand (BOD) and microbiological water quality in Lake Superior. However, KAc concentrations due to application to 25% of the roads in the Miller Creek watershed are predicted to be above the toxic limit for water fleas. We believe that KAc could be used in the most precarious winter driving safety locations, but not over all watershed roads or for all storms. Acetate could be used as a general organic anti-icer, but in combination with another cation, such as sodium or magnesium.
The Impact of Stormwater Infiltration Practices on Groundwater Quality
(St. Anthony Falls Laboratory, 2014-07) Nieber, John L.; Arika, Caleb; Lahti, L.; Gulliver, John S.; Weiss, Peter T.
Establishing enhanced infiltration sites for the control of stormwater runoff in developed areas is becoming a common practice among municipalities, departments of transportation, other government entities, and private entities. One of the purposes of enhanced filtration is to control the volume and rate of runoff from developed areas in order to keep the level of runoff close to that of undeveloped conditions. Another purpose is to capture the stormwater so that contaminants contained in the stormwater will be treated through the process of water infiltrating and flowing through the soil profile. With the increasing adoption of enhanced infiltration practices there is a growing concern that these practices might be putting the quality of the groundwater resources underlying some of these practices in jeopardy. In recent years there have been some efforts to quantify the potential for degradation of groundwater resources by infiltrated stormwater. The study described in this report is an effort to quantify the potential for contaminants to reach the groundwater resources in the Twin Cities Metropolitan Area, Minnesota. A literature review was first conducted to identify concerns with regard to groundwater contamination and the extent of the research that has been completed with regard to these issues. The field study was then conducted over a period of 18 months in which three sites containing enhanced infiltration practices were monitored to quantify the amount of contaminants reaching depths large enough to infer that the contaminants would eventually reach the underlying surficial aquifer. The sites investigated included an infiltration basin near the St. Paul campus of the University of Minnesota (referred to as the Sheep Pasture, SP), a large infiltrating rain garden located within Como Park (referred to as the Hamline-Midway Ave. site, HM), and an infiltration gallery constructed in a formerly industrial area located at Beacon Bluff (referred to as BB) in the eastern side of St. Paul. These sites were selected from a number of potential sites based on the criteria: 1) should have been functioning long enough to contain contaminants; (2) be local for convenience of access; and (3) represent one of the infiltration practices that are of primary concern with regard to groundwater pollution.
Iron Enhanced Sand Filters Performance and Maintenance Meta-Analysis
(2025-04-15) Burrows, Levi J.; Gulliver, John S.; Erickson, Andrew J.; Weiss, Peter T.
Monitoring an Iron-Enhanced Sand Filter for Phosphorus Capture from Agricultural Tile Drainage
(2017-06) Erickson, Andrew J.; Gulliver, John S.; Weiss, Peter T.
Monitoring an Iron-Enhanced Sand Filter Trench for the Capture of Phosphate from Stormwater Runoff
(2015-09) Erickson, Andrew J.; Gulliver, John S.; Weiss, Peter T.
This monitoring project was performed on an iron enhanced sand filtration (IESF) trench in the City of Prior Lake. Water from the pond and IESF trench discharges into a wetland that ultimately drains into Upper Prior Lake. In 2002, Upper Prior Lake was listed on Minnesota’s 303(d) List of Impaired Waters for nutrient/eutrophication biological indicators with aquatic recreation being impaired. Water quality has been reduced due to excessive phosphorus loading. According to the TMDL implementation plan developed for Spring Lake and Upper Prior Lake, the total phosphorus load must be reduced by 83% and 41%, respectively, to meet water quality goals. Overall, for 28 monitored natural rainfall/runoff events from 2013-2015, the IESF trench removed 26% of the phosphate mass load it received, though after non-routine maintenance in August 2014 the performance improved to 45% phosphate mass load reduction. These results indicate the importance of maintenance. A newer installation was previously monitored, and found to retain 71% of the phosphate (Erickson and Gulliver 2010). Most of the overall phosphate load reduction was achieved during larger events that had comparatively high influent phosphate concentrations (32.3 – 125.2 μg/L) and mass loads. Many small events in this investigation with low influent phosphate concentrations (3.8 – 38.4 μg/L) or mass loads exhibited negative removal (i.e., effluent mass load > influent mass load). The high effluent phosphate concentrations are suspected to be caused by the degradation of floating plants (primarily duckweed) that were deposited on the surface of the filter trench. As mentioned above, nonroutine maintenance to remove this material resulted in substantial performance improvement. After this maintenance, positive removal was observed for influent concentrations ranging from 6.3 – 44.1 μg/L. Detailed results, maintenance activities, design and operating & maintenance recommendations, and lessons learned are given within this report.
Permeable Pavements in Cold Climates: State of the Art and Cold Climate Case Studies
(Center for Transportation Studies, University of Minnesota, 2015-06) Weiss, Peter T.; Kayhanian, Masoud; Khazanovich, Lev; Gulliver, John S.
This document is an extensive review of full-depth permeable pavements including porous asphalt, pervious concrete, and permeable interlocking concrete pavers (PICP). Also included is a brief section on articulated concrete blocks/mats. The main topics, which have been divided into chapters, include structural and mix design, hydrologic design, hydraulic performance (i.e. infiltration capacity), maintenance needs/frequency/actions, the impact of permeable pavement on water quality, results of a highway shoulder feasibility study, knowledge gaps, and several cold climate case studies from the United States and Canada. While progress has recently been made with the relatively new permeable pavement technology, researchers have also identified many unresolved issues that are not well understood. These include a methodology to measure subgrade infiltration rates, filling data gaps related to structural integrity, construction, and related issues associated with permeable pavements, determining what maintenance activities are most effective on various pavement types and how frequently specific maintenance actions should be performed, a better understanding of the processes involved in the observed reduction of contaminant concentrations in stormwater flowing through permeable pavements, and a better understanding of the performance of permeable pavements over a time frame that better corresponds with a life-span of 20 years.
Phosphorus Release from Sediments in Lake Winona
(2009-02) Wang, Hong; Weiss, Peter T.; Gulliver, John S.
Stormwater BMP Inspection and Maintenance Resource Guide
(Minnesota Department of Transportation, 2024-06) Erickson, Andrew J.; Gulliver, John S.; Weiss, Peter T.
Stormwater treatment practices, often referred to as stormwater best management practices (BMPs), require a substantial commitment to maintenance, including regular inspections and assessments. Existing regulations require governmental units to develop a systematic approach for ongoing inspection and maintenance to ensure that they are achieving their desired treatment goals. A lack of maintenance will lead to a decrease in BMP performance and will often result in expensive rehabilitation or rebuild. In 2009, SRF Consulting produced a maintenance guide for the Local Road Research Board (LRRB) (Marti, et al. 2009). In 2023, the LRRB commissioned the University of Minnesota St. Anthony Falls Laboratory to update this guide to reflect new best practices. The Stormwater BMP Inspection and Maintenance Resource Guide (the Guide) is a supplement to the Minnesota Stormwater Manual (MPCA 2023) and will help the reader plan for recommended long-term maintenance activities through guidance on visual inspection, testing, and monitoring methods for identifying what maintenance is needed, and when it is needed. The Guide describes inspection and maintenance for constructed stormwater ponds (both dry and wet) and wetlands, underground sedimentation practices, infiltration practices, filtration practices, bioretention practices, permeable pavements, and stormwater harvesting. In addition, the Guide includes a section on Meeting Stormwater Management Objectives, which provides information on achieving reductions for sediment, phosphorus, nitrogen, metals, chloride, pathogens, and organic chemicals. The Guide also includes Field Inspections Resources, which contains inspection checklists and maintenance activity recommendations for all of the practices listed above.
Stormwater Treatment: Assessment and Maintenance
(St. Anthony Falls Laboratory, 2010-06) Erickson, Andrew J.; Weiss, Peter T.; Gulliver, John S.
During the 2005 – 2007 biennium, the Minnesota Pollution Control Agency (MPCA) provided funding to the University of Minnesota for “Assessment of Stormwater Management Practices on the Water Quality of Runoff.” One of the primary deliverables of the project was the Manual, “Assessment of Stormwater Best Management Practices,” (Gulliver and Anderson, 2007). Funding for this work was continued in the 2007 – 2009 biennium with Phase II of the project, titled “Assessment and Maintenance of Stormwater Best Management Practices” which culminated in the publication of the on-line manual, “Stormwater Treatment: Assessment and Maintenance” at http://stormwaterbook.safl.umn.edu/ in 2010.
Total Daily Maximum Daily Load Demonstration Study
(St. Anthony Falls Laboratory, 2011-08) Weiss, Peter T.; Gulliver, John S.; Erickson, Andrew J.
The P8 watershed water quality model was used to model performance of stormwater best management practices (BMPs) in the Lake Como watershed. Lake Como has a draft TMDL that will require 60% retention of the phosphorus that is currently discharging into the lake. The model indicates that current stormwater BMPs are retaining 32% of phosphorus discharge, if properly maintained. This will fall to 21% if sufficient maintenance is not performed. The ponds in the Lake Como watershed do not have as much of a decrease in performance if maintenance is not performed, but also do not remove as high a percent of the incoming phosphorus. To achieve the draft TMDL goals, approximately 20.5 acre-ft of infiltration practices or enhanced sand filters will need to be strategically placed in the watershed.

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