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:'''Column G: Public outreach component'''. The user selects from a dropdown list with the options Yes or No. This applies to MS4 permittees who are attempting to meet Minimum Control Measures 1 or 2. | :'''Column G: Public outreach component'''. The user selects from a dropdown list with the options Yes or No. This applies to MS4 permittees who are attempting to meet Minimum Control Measures 1 or 2. | ||
− | Filling out this checklist fulfills permit requirements 22.3 and 22.4, as long as Columns B, C, D and E are completed. However, if the sources are not mapped, then an inventory (i.e. | + | Filling out this checklist fulfills permit requirements 22.3 and 22.4, as long as Columns B, C, D and E are completed and the source locations are mapped. However, if the sources are not mapped, then an inventory (i.e. addresses of bacteria source locations) needs to be documented. |
==Supporting information== | ==Supporting information== | ||
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===MS4 Infrastructure - Illegal dumping=== | ===MS4 Infrastructure - Illegal dumping=== | ||
− | + | RV dumping or leaking into the storm drains, particularly at vacation destinations, can contribute bacteria and pathogens to the storm sewer system, either by directly dumping into storm drains or by dumping onto impermeable surfaces that drain to the storm sewer system. Illicit RV dumping can be managed by providing public education on appropriate practices, publicizing RV dump locations, by proving a citizen’s reporting hotline, and by publicizing fines ([http://www.asce-pgh.org/Resources/EWRI/Pathogens%20Paper%20August%202014.pdf PATHOGENS in Urban Stormwater Systems]). For an example of an RV dumping brochure, see the brochure [http://www.sandiego.gov/thinkblue/pdf/rvdumpcard.pdf “Think Blue San Diego”]. | |
− | '''Where/when is this a concern''': There are limited direct bacteria sources associated with illegal dumping (e.g. diapers, pet waste). However, illegal dumping of organic material (e.g. yard waste, oil) can act as a food source for microbes in the storm sewer system. | + | :'''Where/when is this a concern''': There are limited direct bacteria sources associated with illegal dumping (e.g. diapers, pet waste). However, illegal dumping of organic material (e.g. yard waste, oil) can act as a food source for microbes in the storm sewer system. |
− | '''Management strategies''': | + | :'''Management strategies''': |
− | *Education, such as through schools and through community awareness groups, about the costs and dangers incurred by illegal dumping. | + | :*Education, such as through schools and through community awareness groups, about the costs and dangers incurred by illegal dumping. |
− | *Create safe, public-friendly waste disposal options and advertise them. | + | :*Create safe, public-friendly waste disposal options and advertise them. |
− | *Create laws that impose stiff fines for the perpetrators and advertise these stiff fines. | + | :*Create laws that impose stiff fines for the perpetrators and advertise these stiff fines. |
− | '''Suggested references''': No specific references recommended. Conduct a web search for more information. | + | :'''Suggested references''': No specific references recommended. Conduct a web search for more information. |
===MS4 Infrastructure - Street litter/decaying plant matter=== | ===MS4 Infrastructure - Street litter/decaying plant matter=== | ||
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Street litter and plant material indirectly contribute to bacteria loads by providing a food source and habitat for bacteria populations to survive and grow. A study in the [https://issuu.com/swwtwater/docs/minnehaha_creek_bacterial_source_id Minnehaha Creek Watershed], Minnesota, indicated organic material is an important contributor to bacteria in stormwater runoff. | Street litter and plant material indirectly contribute to bacteria loads by providing a food source and habitat for bacteria populations to survive and grow. A study in the [https://issuu.com/swwtwater/docs/minnehaha_creek_bacterial_source_id Minnehaha Creek Watershed], Minnesota, indicated organic material is an important contributor to bacteria in stormwater runoff. | ||
− | '''Where/when is this a concern'''<br> | + | :'''Where/when is this a concern'''<br> |
There are few studies that specifically focus on street debris as a source for bacteria. This is likely to be an important source during times of the year when organic debris is in streets and temperatures and moisture conditions are conducive to bacterial growth. Spring and early fall are therefore the most likely times for this to be an important source of bacteria. | There are few studies that specifically focus on street debris as a source for bacteria. This is likely to be an important source during times of the year when organic debris is in streets and temperatures and moisture conditions are conducive to bacterial growth. Spring and early fall are therefore the most likely times for this to be an important source of bacteria. | ||
− | '''Management strategies'''<br> | + | :'''Management strategies'''<br> |
Pollution prevention and source control practices, such as [https://stormwater.pca.state.mn.us/index.php?title=Street_sweeping street sweeping], are recommended to control street litter and plant material. [https://stormwater.pca.state.mn.us/index.php?title=Residential_prevention_practices_for_bacteria This table] provides a summary of additional practices for residential areas, many designed to control sources of organic material to the storm sewer system. | Pollution prevention and source control practices, such as [https://stormwater.pca.state.mn.us/index.php?title=Street_sweeping street sweeping], are recommended to control street litter and plant material. [https://stormwater.pca.state.mn.us/index.php?title=Residential_prevention_practices_for_bacteria This table] provides a summary of additional practices for residential areas, many designed to control sources of organic material to the storm sewer system. | ||
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[[File:IDDE Sample.jpg|500 px|right|thumb|alt=This image shows a person collecting a water sample from an outfall |<font size=2>Image of a person collecting a water sample from an outfall </font size>]] | [[File:IDDE Sample.jpg|500 px|right|thumb|alt=This image shows a person collecting a water sample from an outfall |<font size=2>Image of a person collecting a water sample from an outfall </font size>]] | ||
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The United States Environmental Protection Agency defines an illicit discharge as, “any discharge into a storm drain system that is not composed entirely of stormwater.” The Minnesota Municipal Separate Storm Sewer System (MS4) General Permit defines illicit discharge as any discharge to a municipal separate storm sewer that is not composed entirely of stormwater except discharges pursuant to a NPDES permit (other than the NPDES permit for discharges from the municipal separate storm sewer) and discharges resulting from firefighting activities. | The United States Environmental Protection Agency defines an illicit discharge as, “any discharge into a storm drain system that is not composed entirely of stormwater.” The Minnesota Municipal Separate Storm Sewer System (MS4) General Permit defines illicit discharge as any discharge to a municipal separate storm sewer that is not composed entirely of stormwater except discharges pursuant to a NPDES permit (other than the NPDES permit for discharges from the municipal separate storm sewer) and discharges resulting from firefighting activities. | ||
− | '''Where/when is this a concern'''<br> | + | :'''Where/when is this a concern'''<br> |
There are many potential illicit discharges to an MS4. The concern here are sources that contribute bacteria and pathogens, or that contribute pollutants that may promote bacteria and pathogen growth (e.g. organic sources). The most important potential sources are likely to be sanitary sewer connections, including broken sanitary sewer lines where septage seeps into a storm sewer line, cross-connections, and and straight pipe discharges. These sources contribute high concentrations of bacteria and pathogens to the storm sewer system. | There are many potential illicit discharges to an MS4. The concern here are sources that contribute bacteria and pathogens, or that contribute pollutants that may promote bacteria and pathogen growth (e.g. organic sources). The most important potential sources are likely to be sanitary sewer connections, including broken sanitary sewer lines where septage seeps into a storm sewer line, cross-connections, and and straight pipe discharges. These sources contribute high concentrations of bacteria and pathogens to the storm sewer system. | ||
− | '''Management strategies'''<br> | + | :'''Management strategies'''<br> |
Stormwater practitioners and managers covered under the MS4 General permit must develop and implement an illicit discharge detection and elimination (IDDE) program. Information on permit requirements [https://stormwater.pca.state.mn.us/index.php?title=MCM_3_Illicit_Discharge_Detection_and_Elimination is found here]. | Stormwater practitioners and managers covered under the MS4 General permit must develop and implement an illicit discharge detection and elimination (IDDE) program. Information on permit requirements [https://stormwater.pca.state.mn.us/index.php?title=MCM_3_Illicit_Discharge_Detection_and_Elimination is found here]. | ||
Many illicit discharges occur during dry weather when storm flows are not contributing, or are intermittent. This may aid in detecting illicit discharges, since storm sewer discharges during dry weather or intermittent discharges may indicate the presence of illicit discharges. There are several techniques for detecting illicit discharges, including outfall monitoring, use of tracers (e.g. smoke, dye), and use of electronic equipment (e.g. cameras). More specific information on some illicit discharges and methods for identifying them are found in the sections on[https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Combined_sewer_overflows_.28CSOs.29 combined sewer overflows], [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Sanitary_sewer_overflows_.28SSOs.29 sanitary sewer overflows], [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Sanitary_sewer_inflow_and_infiltration_.28I.26I.29 inflow and infiltration], and [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Illicit_sanitary_connections_to_MS4s illicit connections to sanitary sewers]. | Many illicit discharges occur during dry weather when storm flows are not contributing, or are intermittent. This may aid in detecting illicit discharges, since storm sewer discharges during dry weather or intermittent discharges may indicate the presence of illicit discharges. There are several techniques for detecting illicit discharges, including outfall monitoring, use of tracers (e.g. smoke, dye), and use of electronic equipment (e.g. cameras). More specific information on some illicit discharges and methods for identifying them are found in the sections on[https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Combined_sewer_overflows_.28CSOs.29 combined sewer overflows], [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Sanitary_sewer_overflows_.28SSOs.29 sanitary sewer overflows], [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Sanitary_sewer_inflow_and_infiltration_.28I.26I.29 inflow and infiltration], and [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Illicit_sanitary_connections_to_MS4s illicit connections to sanitary sewers]. | ||
− | '''Suggested references'''<br> | + | :'''Suggested references'''<br> |
For more information, see the following documents. | For more information, see the following documents. | ||
*[https://www3.epa.gov/npdes/pubs/idde_manualwithappendices.pdf Illicit Discharge Detection and Elimination: A Guidance Manual for Program Development and Technical Assessments] - Center for Watershed Protection | *[https://www3.epa.gov/npdes/pubs/idde_manualwithappendices.pdf Illicit Discharge Detection and Elimination: A Guidance Manual for Program Development and Technical Assessments] - Center for Watershed Protection | ||
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[[File:Overwatering.jpg|300px|thumb|alt=image of overirrigating|<font size>Example of overirrigating (Image courtesy [http://mjslawn.com/proper-watering-taking-care-of-your-lawn/ Chesapeake Lawn Service])</font size>]] | [[File:Overwatering.jpg|300px|thumb|alt=image of overirrigating|<font size>Example of overirrigating (Image courtesy [http://mjslawn.com/proper-watering-taking-care-of-your-lawn/ Chesapeake Lawn Service])</font size>]] | ||
− | + | Irrigation runoff is an allowed discharge to storm sewer systems, provided there are no illicit pollutants in the discharge. Irrigation runoff can contribute bacteria and pathogens to runoff and mobilize sources within the storm sewer system. In particular, irrigation runoff is a potentially important source of dry weather flows in residential and commercial areas. A study in the [https://issuu.com/swwtwater/docs/minnehaha_creek_bacterial_source_id Minnehaha Creek Watershed], Minnesota, indicated over-irrigation and subsequent runoff from lawns was an important source of bacteria. | |
+ | :'''Where/when is this a concern'''<br> | ||
+ | A study in San Diego indicated a higher frequency of runoff in residential areas compared to commercial land uses. An Alabama study indicated wet-weather samples having mostly higher enterococci levels than E. coli, while dry weather source area samples (such as springs and irrigation runoff) had higher E. coli levels ([https://www3.epa.gov/npdes/pubs/sw_idde_bacteria.pdf Shergill and Pitt, 1984]). The contribution of dry weather inflows from irrigation runoff has also been known to foster in-situ bacterial growth (Geosyntec 2010). | ||
− | + | :'''Management strategies'''<br> | |
− | + | The primary focus on reducing inputs from irrigation should focus on reducing overirrigation. Effective methods to reduce irrigation runoff include development of educational outreach, increased inspections, fines for overwatering, tiered water rates, provide irrigation controller rebates or distribution of smart irrigation controllers and/or other financial incentive programs that decrease watering volume ([https://www.sandiego.gov/sites/default/files/sdrclrpupdate_0.pdf Geosyntec 2012]). A residential runoff study in Orange County conducted in five neighborhoods found dryweather runoff decreased by 50% in areas where weather-based irrigation controllers were installed ([https://pubs.usgs.gov/of/2004/1019/chap1.html IRWD and OCMWD 2004]). Berg et al. (2009) found dry-weather runoff reductions of 25% to 50% for a similar study of 4,100 Smart Timers installed in residential and commercial areas. Promoting better irrigation runoff management also reduces water waste and can improve water quality. | |
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− | '''Management strategies'''<br> | ||
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− | The primary focus on reducing inputs from irrigation should focus on reducing overirrigation. Effective methods to reduce irrigation runoff include development of educational outreach, increased inspections, fines for overwatering, tiered water rates, provide irrigation controller rebates or distribution of smart irrigation controllers and/or other financial incentive programs that decrease watering volume ([https://www.sandiego.gov/sites/default/files/sdrclrpupdate_0.pdf Geosyntec 2012]). A residential runoff study in Orange County conducted in five neighborhoods found dryweather runoff decreased by 50% in areas where weather-based irrigation controllers were installed ([https:// | ||
===MS4 Infrastructure - Biofilms/regrowth in MS4=== | ===MS4 Infrastructure - Biofilms/regrowth in MS4=== | ||
[[File:Biofilms.png|300px|thumb|alt=image of biofilm|<font size=3>Schematic of biofilm growth and dispersion. Image [https://www2.le.ac.uk/projects/vgec/highereducation/topics/microbial-genetics-1/infection/biofilms University of Leicester].</font size>]] | [[File:Biofilms.png|300px|thumb|alt=image of biofilm|<font size=3>Schematic of biofilm growth and dispersion. Image [https://www2.le.ac.uk/projects/vgec/highereducation/topics/microbial-genetics-1/infection/biofilms University of Leicester].</font size>]] | ||
− | + | Regrowth of bacteria in the storm sewer system has been documented but is poorly understood. Regrowth is problematic because it may negate upstream efforts to control bacteria and pathogens. | |
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− | + | :'''Where/when is this a concern'''<br> | |
+ | Regrowth typically occurs in biofilms. Biofilms are surface-attached communities of microorganisms that undergo cell attachment, growth, detachment, and sloughing. Biofilms are normally extremely diverse and include a wide variety of bacteria, including pathogenic bacteria. The pathogens E. coli O157:H7, Salmonella enterica, and Campylobacter jejuni are all known to form biofilms. Further, biofilm formation can favor the survival of all three of these organisms under both typical environmental conditions and under active disinfection. Biofilms act as a source of bacteria in stormwater runoff during periods of higher flow, which dislodges bacteria from the biofilms. | ||
+ | :'''Management strategies'''<br> | ||
Factors that commonly limit the survival of bacterial pathogens in biofilms include low levels of available nutrients and organic material, non-favorable oxygen concentrations, and the competitive, antagonistic and predatory activities of the indigenous microbial population. High stormflow rates cause detachment and sloughing of biofilms. Biofilms can develop in urban storm sewer piping and in streets. Some researchers have questioned the utility of using indicator bacteria in conditions favorable for biofilm growth, since indicator bacteria survive and grown in biofilms while many pathogenic bacteria do not. | Factors that commonly limit the survival of bacterial pathogens in biofilms include low levels of available nutrients and organic material, non-favorable oxygen concentrations, and the competitive, antagonistic and predatory activities of the indigenous microbial population. High stormflow rates cause detachment and sloughing of biofilms. Biofilms can develop in urban storm sewer piping and in streets. Some researchers have questioned the utility of using indicator bacteria in conditions favorable for biofilm growth, since indicator bacteria survive and grown in biofilms while many pathogenic bacteria do not. | ||
Irrigation runoff can contribute to formation of biofilms in storm sewers that can be an on-going source of bacteria discharged from the storm sewer system [https://www.denvergov.org/content/dam/denvergov/Portals/711/documents/greeninfrastructure/GI_Implementation-Section3.pdf Green Infrastructure Implementation Strategy] (2018). Other factors that may favor biofilm development include organic debris in streets, favorable surfaces for attachment within the storm sewer system (e.g. submerged aprons, particularly those constructed of concrete), and increased loading with natural sediments containing naturally occurring biofilms, stormwater enriched in bacteria. During prolonged periods between runoff events, environmental biofilms (i.e. naturally-occurring) appear to outcompete and replace biofilms consisting of bacteria originating from stormwater flows. Enhancing the storm sewer environment to favor environmental bacteria may be one approach to reducing loading of bacteria from stormwater flows. | Irrigation runoff can contribute to formation of biofilms in storm sewers that can be an on-going source of bacteria discharged from the storm sewer system [https://www.denvergov.org/content/dam/denvergov/Portals/711/documents/greeninfrastructure/GI_Implementation-Section3.pdf Green Infrastructure Implementation Strategy] (2018). Other factors that may favor biofilm development include organic debris in streets, favorable surfaces for attachment within the storm sewer system (e.g. submerged aprons, particularly those constructed of concrete), and increased loading with natural sediments containing naturally occurring biofilms, stormwater enriched in bacteria. During prolonged periods between runoff events, environmental biofilms (i.e. naturally-occurring) appear to outcompete and replace biofilms consisting of bacteria originating from stormwater flows. Enhancing the storm sewer environment to favor environmental bacteria may be one approach to reducing loading of bacteria from stormwater flows. | ||
+ | :'''Suggested references'''<br> | ||
For more information, see [http://www.asce-pgh.org/Resources/EWRI/Pathogens%20Paper%20August%202014.pdf Urban Water Resources Research Council] (2014), [https://www.stormh2o.com/bmps/article/13007108/when-bacteria-call-the-storm-drain-home Roberts] (2012), and [https://dspace.mit.edu/bitstream/handle/1721.1/82805/862116767-MIT.pdf;sequence=2 Burkhart] (2013). | For more information, see [http://www.asce-pgh.org/Resources/EWRI/Pathogens%20Paper%20August%202014.pdf Urban Water Resources Research Council] (2014), [https://www.stormh2o.com/bmps/article/13007108/when-bacteria-call-the-storm-drain-home Roberts] (2012), and [https://dspace.mit.edu/bitstream/handle/1721.1/82805/862116767-MIT.pdf;sequence=2 Burkhart] (2013). | ||
===MS4 Infrastructure - Leaky sewer pipes=== | ===MS4 Infrastructure - Leaky sewer pipes=== | ||
− | + | Leaky sewer pipes potentially can contribute very high concentrations of bacteria to storm sewer systems. | |
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+ | :'''Where/when is this a concern'''<br> | ||
+ | Leaking sewer systems are more common in areas with aging infrastructure, where contributions from leaking systems can be as high as 20 percent of annual flow in the sanitary sewer system. For a detailed discussion of contributions from leaking sewer systems, see [https://owl.cwp.org/mdocs-posts/sercu_2011_sewage_exfiltration_source/ Sercu et al.] (2011), [https://www.researchgate.net/publication/47690500_An_approach_to_identify_urban_groundwater_recharge Vasquez-Sune et al.] (2011), [https://www.researchgate.net/publication/226578714_Quantification_of_Groundwater_Recharge_in_the_City_of_Nottingham_UK Yang et al.] (1999), [https://www.semanticscholar.org/paper/Assessment-of-sewer-leakage-by-means-of-and-tests-Rutsch/9ccaadc8f9fe15e17c1d0d3eeb6b5c638701e65f Rutsch] (2006), and [https://www.researchgate.net/publication/51770136_Quantification_of_sewer_leakage_by_a_continuous_tracer_method Prigiobbe and Giulianelli] (2011). | ||
− | + | :'''Management strategies'''<br> | |
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For more information on potential effects of leaking sewer infrastructure, methods of detecting leaks, and management strategies, [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Illicit_sanitary_connections_to_MS4s see the section on illicit discharges] and [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Sanitary_sewer_inflow_and_infiltration_.28I.26I.29 the section on sanitary sewer inflow and infiltration]. | For more information on potential effects of leaking sewer infrastructure, methods of detecting leaks, and management strategies, [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Illicit_sanitary_connections_to_MS4s see the section on illicit discharges] and [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Municipal_Sanitary_Infrastructure_-_Sanitary_sewer_inflow_and_infiltration_.28I.26I.29 the section on sanitary sewer inflow and infiltration]. | ||
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[[File:Healthy lawns.JPG|thumb|300px|alt=image|<font size=3>Lawns can be an important source of bacteria during the growing season. Maintaining healthy lawns that improve water retention is an effective way to reduce runoff from lawns.</font size>]] | [[File:Healthy lawns.JPG|thumb|300px|alt=image|<font size=3>Lawns can be an important source of bacteria during the growing season. Maintaining healthy lawns that improve water retention is an effective way to reduce runoff from lawns.</font size>]] | ||
− | + | Permeable surfaces contribute to runoff when the rate of water application from precipitation, melting snow, or irrigation exceeds the infiltration capacity of the soil. Factors contributing to runoff from permeable surfaces include compacted soils, soils with naturally low infiltration rates (e.g D soils), saturated soils, frozen soils, and soils subject to over-irrigation. Sources of bacteria to permeable surfaces include birds, small mammals, dogs, etc. | |
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+ | :'''When/where is this a concern''' | ||
Urban lawns and other grass areas can be a source of bacteria and pathogens to stormwater runoff. Concentrations of indicator bacteria in runoff typically exceed water quality standards in all land uses, often by more than an order of magnitude, with concentrations tending to be higher from residential areas compared to commercial, industrial, and open space land uses ([https://stormwater.pca.state.mn.us/index.php?title=Concentrations_of_contaminants_found_in_stormwater Minnesota Stormwater Manual]). Grass swales and grass strips typically have higher concentrations of bacteria and enterococci in outflow water compared to inflow, although if these practices infiltrate water the total loading may be decreased by the practices ([https://www.waterrf.org/system/files/resource/2020-11/DRPT-4968_0.pdf International BMP Database]). Contributions of bacteria to runoff from grass areas is not well understood. [http://lshs.tamu.edu/docs/lshs/end-notes/evaluation%20of%20indicator%20bacteria%20export%20from%20an%20urban%20watershed-0796882443/evaluation%20of%20indicator%20bacteria%20export%20from%20an%20urban%20watershed.pdf Hathaway and Hunt] (2010) conducted a study of bacteria in runoff from residential areas in North Carolina and concluded the following. | Urban lawns and other grass areas can be a source of bacteria and pathogens to stormwater runoff. Concentrations of indicator bacteria in runoff typically exceed water quality standards in all land uses, often by more than an order of magnitude, with concentrations tending to be higher from residential areas compared to commercial, industrial, and open space land uses ([https://stormwater.pca.state.mn.us/index.php?title=Concentrations_of_contaminants_found_in_stormwater Minnesota Stormwater Manual]). Grass swales and grass strips typically have higher concentrations of bacteria and enterococci in outflow water compared to inflow, although if these practices infiltrate water the total loading may be decreased by the practices ([https://www.waterrf.org/system/files/resource/2020-11/DRPT-4968_0.pdf International BMP Database]). Contributions of bacteria to runoff from grass areas is not well understood. [http://lshs.tamu.edu/docs/lshs/end-notes/evaluation%20of%20indicator%20bacteria%20export%20from%20an%20urban%20watershed-0796882443/evaluation%20of%20indicator%20bacteria%20export%20from%20an%20urban%20watershed.pdf Hathaway and Hunt] (2010) conducted a study of bacteria in runoff from residential areas in North Carolina and concluded the following. | ||
*Concentrations of indicator bacteria are lower in winter compared to growing season months | *Concentrations of indicator bacteria are lower in winter compared to growing season months | ||
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*There was no or minimal first flush effect (i.e. bacteria loading is relatively constant throughout a rain event) | *There was no or minimal first flush effect (i.e. bacteria loading is relatively constant throughout a rain event) | ||
+ | :'''Management strategies'''<br> | ||
Practices or factors that potentially contribute to bacteria loading from grass areas include the following. | Practices or factors that potentially contribute to bacteria loading from grass areas include the following. | ||
*Over-watering/irrigating | *Over-watering/irrigating | ||
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===Municipal Sanitary Infrastructure - Combined sewer overflows (CSOs)=== | ===Municipal Sanitary Infrastructure - Combined sewer overflows (CSOs)=== | ||
− | + | Combined sewer systems (CSS) are sewers that are designed to collect rainwater runoff, domestic sewage, and industrial wastewater in the same pipe. When the capacity of the CSS is exceeded, excess water can bypass treatment and bypassed flow will be mixed with the treated water prior to disinfection and just prior to discharge to the receiving water. While both stormwater runoff and sanitary sewer discharges contain bacteria, concentrations are much higher in untreated sewage. Thus, CSOs can lead to very high concentrations of bacteria in water delivered to receiving waters. | |
+ | '''Where/when is this a concern''' | ||
+ | During wet weather conditions, the volume of stormwater runoff can exceed the capacity of the CSS infrastructure, including both the piping system and/or the treatment plant. This is common where where older CSS infrastructure is in place, combining sanitary and storm drain flows. | ||
− | ''' | + | :'''Management strategies''' |
+ | Where feasible, CSOs should be separated so that the different water sources do not mix. Because this is typically cost prohibitive, separation can be done strategically in steps, identifying high priority areas and retrofitting those first. Implementing stormwater runoff capture and infiltration may reduce the CSO problem by decreasing stormflow volumes. Diversions or upgrades to water treatment facilities are other options. | ||
− | + | :'''Suggested references''' | |
− | + | For more information, see [https://www.epa.gov/npdes/combined-sewer-overflows-csos], [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1257666/], [https://www3.epa.gov/npdes/pubs/sepa.pdf], [https://www3.epa.gov/npdes/pubs/altdis.pdf]. | |
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===Municipal Sanitary Infrastructure - Sanitary sewer overflows (SSOs)=== | ===Municipal Sanitary Infrastructure - Sanitary sewer overflows (SSOs)=== | ||
[[File:Sources of ssos.png|thumb|300px|alt=image of sources of SSOs|<font size=3>Sources of SSOs, from an EPA study of six communities ([https://www3.epa.gov/npdes/pubs/ssodesc.pdf]).</font size>]] | [[File:Sources of ssos.png|thumb|300px|alt=image of sources of SSOs|<font size=3>Sources of SSOs, from an EPA study of six communities ([https://www3.epa.gov/npdes/pubs/ssodesc.pdf]).</font size>]] | ||
− | + | Sanitary sewer systems collect and transport domestic, commercial, and industrial wastewater. Some sanitary sewer systems may contain limited amounts of stormwater and infiltrated ground water to treatment facilities, but they are designed to carry just sewage and industrial wastewater. Occasionally, sanitary sewers will release raw sewage. These types of releases are called sanitary sewer overflows (SSOs). SSOs that discharge to surface waters are considered point source discharges and are thus prohibited unless authorized by a NPDES permit. SSOs may be indicative of improper operation and maintenance of the sewer systems, and may violate NPDES permit conditions. | |
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'''Where/when is this a concern'''<br> | '''Where/when is this a concern'''<br> | ||
− | + | Possible causes of SSOs include blockages, line breaks, sewer defects that allow stormwater and groundwater to overload the system, power failures, improper sewer design, and vandalism. The adjacent image indicates line blockages appear to be an important cause of SSOs. An EPA survey indicated SSOs are most common during wet weather flows. | |
'''Management strategies'''<br> | '''Management strategies'''<br> | ||
− | + | Effective illicit discharge and elimination practices and programs minimize the occurrence and impacts from SSOs. Other management strategies include the following. | |
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*Sewer system cleaning and maintenance | *Sewer system cleaning and maintenance | ||
*Reducing infiltration and inflow through system rehabilitation and repairing broken or leaking service lines | *Reducing infiltration and inflow through system rehabilitation and repairing broken or leaking service lines | ||
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*Construction wet weather storage and treatment facilities to treat excess flows | *Construction wet weather storage and treatment facilities to treat excess flows | ||
+ | '''Suggested references'''<br> | ||
For more information, see [https://www.epa.gov/npdes/sanitary-sewer-overflows-ssos], [https://www3.epa.gov/npdes/pubs/ssodesc.pdf], [http://www.asce-pgh.org/Resources/EWRI/Pathogens%20Paper%20August%202014.pdf#%5B%7B%22num%22%3A680%2C%22gen%22%3A0%7D%2C%7B%22name%22%3A%22XYZ%22%7D%2C70%2C720%2C0%5D], [https://www.epa.gov/npdes/sanitary-sewer-overflow-sso-frequent-questions] | For more information, see [https://www.epa.gov/npdes/sanitary-sewer-overflows-ssos], [https://www3.epa.gov/npdes/pubs/ssodesc.pdf], [http://www.asce-pgh.org/Resources/EWRI/Pathogens%20Paper%20August%202014.pdf#%5B%7B%22num%22%3A680%2C%22gen%22%3A0%7D%2C%7B%22name%22%3A%22XYZ%22%7D%2C70%2C720%2C0%5D], [https://www.epa.gov/npdes/sanitary-sewer-overflow-sso-frequent-questions] | ||
===Municipal Sanitary Infrastructure - Sanitary sewer inflow and infiltration (I&I)=== | ===Municipal Sanitary Infrastructure - Sanitary sewer inflow and infiltration (I&I)=== | ||
[[File:I&I.png|300px|thumb|alt=image showing how to estimate I&I|<font size=3>Example of how to estimate inputs from infiltration and inflow ([https://www3.epa.gov/region1/sso/pdfs/Guide4EstimatingInfiltrationInflow.pdf]).</font size>]] | [[File:I&I.png|300px|thumb|alt=image showing how to estimate I&I|<font size=3>Example of how to estimate inputs from infiltration and inflow ([https://www3.epa.gov/region1/sso/pdfs/Guide4EstimatingInfiltrationInflow.pdf]).</font size>]] | ||
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Groundwater infiltration and rainfall derived inflow and infiltration, commonly referred to as inflow, are components of most sanitary sewer systems. These inputs, called I&I, should be a minor component of the sanitary sewer flow. However, infiltration and inflow may | Groundwater infiltration and rainfall derived inflow and infiltration, commonly referred to as inflow, are components of most sanitary sewer systems. These inputs, called I&I, should be a minor component of the sanitary sewer flow. However, infiltration and inflow may | ||
be considered excessive when it is the cause of overflows (SSO) or bypasses in the sanitary sewer system. In addition, I&I is treated at wastewater treatment plants even though it is relatively clean water, resulting in extra cost. | be considered excessive when it is the cause of overflows (SSO) or bypasses in the sanitary sewer system. In addition, I&I is treated at wastewater treatment plants even though it is relatively clean water, resulting in extra cost. | ||
+ | '''Where/when is this a concern'''<br> | ||
EPA provides guidance for estimating the input and importance of I&I in a sanitary sewer system. To assess extraneous water entering your system at least a year of influent flow data to the treatment facility should be examined. For infiltration analysis, flow data collected during the high groundwater periods is used. For inflow analysis, the Average Wet Weather (AWW) flow can be estimated from flow data for a | EPA provides guidance for estimating the input and importance of I&I in a sanitary sewer system. To assess extraneous water entering your system at least a year of influent flow data to the treatment facility should be examined. For infiltration analysis, flow data collected during the high groundwater periods is used. For inflow analysis, the Average Wet Weather (AWW) flow can be estimated from flow data for a | ||
one week period when there has been significant rain. If a single storm event is used to analyze wet weather inflow, it should be an event large enough to cause surface ponding and runoff. Other techniques can be used to determine the presence of I&I, including manhole testing and maintenance, dye tracing, smoke testing, use of cameras, and private property inspection for improper connections. Examples of improper connections include downspouts, groundwater sump pumps, foundation drains, drains from window wells and outdoor basement stairwells and drains from driveways. | one week period when there has been significant rain. If a single storm event is used to analyze wet weather inflow, it should be an event large enough to cause surface ponding and runoff. Other techniques can be used to determine the presence of I&I, including manhole testing and maintenance, dye tracing, smoke testing, use of cameras, and private property inspection for improper connections. Examples of improper connections include downspouts, groundwater sump pumps, foundation drains, drains from window wells and outdoor basement stairwells and drains from driveways. | ||
+ | '''Management strategies'''<br> | ||
Proper evaluation of I&I sources is necessary to manage them. Once detected, they can be eliminated or minimized. Several cities, for example, have programs and ordinances prohibiting illicit connections on private property. | Proper evaluation of I&I sources is necessary to manage them. Once detected, they can be eliminated or minimized. Several cities, for example, have programs and ordinances prohibiting illicit connections on private property. | ||
− | For more information, see [https://www3.epa.gov/region1/sso/pdfs/Guide4EstimatingInfiltrationInflow.pdf], [ | + | '''Suggested references'''<br> |
+ | For more information, see [https://www3.epa.gov/region1/sso/pdfs/Guide4EstimatingInfiltrationInflow.pdf], [https://inbound.envirosight.com/inflow-and-infiltration], [https://www.sehinc.com/news/6-ways-identify-ii-including-3-warning-signs], [https://metrocouncil.org/Wastewater-Water/Planning/Wastewater/Inflow-and-Infiltration.aspx] | ||
===Municipal Sanitary Infrastructure - Illicit sanitary connections to MS4s=== | ===Municipal Sanitary Infrastructure - Illicit sanitary connections to MS4s=== | ||
[[File:IDDE Sample.jpg|300 px|right|thumb|alt=This image shows a person collecting a water sample from an outfall |<font size=2>Image of a person collecting a water sample from an outfall </font size>]] | [[File:IDDE Sample.jpg|300 px|right|thumb|alt=This image shows a person collecting a water sample from an outfall |<font size=2>Image of a person collecting a water sample from an outfall </font size>]] | ||
− | + | The Municipal Separate Storm Sewer System (MS4) General Permit defines illicit discharge as "any discharge to a municipal separate storm sewer that is not composed entirely of stormwater except discharges pursuant to a NPDES permit (other than the NPDES permit for discharges from the municipal separate storm sewer) and discharges resulting from firefighting activities". Not all illicit discharges contain bacteria and pathogens, but examples of illicit discharge sources containing bacteria and pathogens include sewage and septage, washwater, irrigation water, and some commercial and industrial water. | |
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'''Where/when is this a concern'''<br> | '''Where/when is this a concern'''<br> | ||
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Illicit discharges to the storm sewer system can be classified as direct or indirect. Direct discharges are directly connected to the storm drain pipe through a sewage pipe, shop drain, or other kind of pipe. Direct discharges are typically continuous or intermittent and occur when two different kinds of “plumbing” are improperly connected. The three main situations where this occurs are sewage cross-connections, straight pipes, and industrial and commercial cross-connections. Indirect discharges are generated outside the storm drain system and enter through storm drain inlets or by infiltrating through the joints of the pipe. Generally, indirect discharges are intermittent or transitory, with the exception of groundwater seepage. Indirect discharges include groundwater seepage, spills, dumping, outdoor washing, and irrigation. | Illicit discharges to the storm sewer system can be classified as direct or indirect. Direct discharges are directly connected to the storm drain pipe through a sewage pipe, shop drain, or other kind of pipe. Direct discharges are typically continuous or intermittent and occur when two different kinds of “plumbing” are improperly connected. The three main situations where this occurs are sewage cross-connections, straight pipes, and industrial and commercial cross-connections. Indirect discharges are generated outside the storm drain system and enter through storm drain inlets or by infiltrating through the joints of the pipe. Generally, indirect discharges are intermittent or transitory, with the exception of groundwater seepage. Indirect discharges include groundwater seepage, spills, dumping, outdoor washing, and irrigation. | ||
Certain types of illicit discharges can be associated with specific land uses. For example, failing septic systems and irrigation sources are more common in residential areas, while in commercial areas important sources include washing, dumping, and spills. [https://www3.epa.gov/npdes/pubs/idde_chapter-1.pdf This EPA document] provides a table and discussion of likely sources for different land uses. | Certain types of illicit discharges can be associated with specific land uses. For example, failing septic systems and irrigation sources are more common in residential areas, while in commercial areas important sources include washing, dumping, and spills. [https://www3.epa.gov/npdes/pubs/idde_chapter-1.pdf This EPA document] provides a table and discussion of likely sources for different land uses. | ||
+ | '''Management strategies'''<br> | ||
For entities covered under municipal NPDES stormwater permits, [https://stormwater.pca.state.mn.us/index.php?title=MCM_3_Illicit_Discharge_Detection_and_Elimination Minimum Control Measure 3] requires establishment and maintenance of an illicit discharge detection and elimination (IDDE) program. The permit contains [https://stormwater.pca.state.mn.us/index.php?title=MCM_3_Illicit_Discharge_Detection_and_Elimination#MS4_General_Permit_requirements_for_MCM_3 specific items that are required] as part of an IDDE program. | For entities covered under municipal NPDES stormwater permits, [https://stormwater.pca.state.mn.us/index.php?title=MCM_3_Illicit_Discharge_Detection_and_Elimination Minimum Control Measure 3] requires establishment and maintenance of an illicit discharge detection and elimination (IDDE) program. The permit contains [https://stormwater.pca.state.mn.us/index.php?title=MCM_3_Illicit_Discharge_Detection_and_Elimination#MS4_General_Permit_requirements_for_MCM_3 specific items that are required] as part of an IDDE program. | ||
Techniques for detecting illicit discharges include techniques for detecting infiltration and inflow. These include monitoring, dye tracing, smoke detection, use of camera, and focused inspections. | Techniques for detecting illicit discharges include techniques for detecting infiltration and inflow. These include monitoring, dye tracing, smoke detection, use of camera, and focused inspections. | ||
+ | '''Suggested references'''<br> | ||
For more information see [https://www3.epa.gov/npdes/pubs/idde_chapter-1.pdf], [https://www.stormwaterpa.org/media/bmps/MCM3_idde.pdf], [https://www.tceq.texas.gov/assets/public/comm_exec/pubs/gbnep/ms4.pdf]. | For more information see [https://www3.epa.gov/npdes/pubs/idde_chapter-1.pdf], [https://www.stormwaterpa.org/media/bmps/MCM3_idde.pdf], [https://www.tceq.texas.gov/assets/public/comm_exec/pubs/gbnep/ms4.pdf]. | ||
===Other Human Sanitary Sources - Porta-potties (poorly maintained)=== | ===Other Human Sanitary Sources - Porta-potties (poorly maintained)=== | ||
[[File:Portable toilet.jpg|300px|thumb|alt=image portable toilet|<font size=3>Image of portable toilet. Wikipedia [https://creativecommons.org/licenses/by-sa/3.0/deed.en Creative Commons Attribution-Share Alike 3.0 Unported license].</font size>]] | [[File:Portable toilet.jpg|300px|thumb|alt=image portable toilet|<font size=3>Image of portable toilet. Wikipedia [https://creativecommons.org/licenses/by-sa/3.0/deed.en Creative Commons Attribution-Share Alike 3.0 Unported license].</font size>]] | ||
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'''Where/when is this a concern'''<br> | '''Where/when is this a concern'''<br> | ||
− | + | If properly placed and maintained, porta potties should not be a source of bacteria to the stormwater system. However, they have the potential to contribute high concentrations of bacteria and pathogens. In addition, cleaning of portable toilets may contribute other pollutants, such as disinfectants, to runoff. | |
'''Management strategies'''<br> | '''Management strategies'''<br> | ||
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There are numerous fact sheets and guidance documents concerning porta potties. Some useful links are provided below. Common practices for properly managing porta potties include the following. | There are numerous fact sheets and guidance documents concerning porta potties. Some useful links are provided below. Common practices for properly managing porta potties include the following. | ||
*Installation. Ensure that toilets | *Installation. Ensure that toilets | ||
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**If there is no secondary containment, or the spill breached the containment tray, use whatever BMP materials you have available to make sure the spill does not flow into the storm drain (using appropriate personal protective equipment), and call the porta-potty company to have them clean up the spill. | **If there is no secondary containment, or the spill breached the containment tray, use whatever BMP materials you have available to make sure the spill does not flow into the storm drain (using appropriate personal protective equipment), and call the porta-potty company to have them clean up the spill. | ||
+ | '''Suggested references'''<br> | ||
For more information, see [https://www.gotswppp.com/newsletters/The%20Monthly%20Dirt%20-%20Feb2015.pdf], [https://www.sandiegocounty.gov/content/sdc/dpw/watersheds/IndustrialCommercial/Portable_Toilets.html], [https://www.gwinnettcounty.com/static/departments/publicutilities/pdf/WQ-04%20Portable%20Toilet%20Management-%20Final.pdf], and [http://www.asce-pgh.org/Resources/EWRI/Pathogens%20Paper%20August%202014.pdf]. | For more information, see [https://www.gotswppp.com/newsletters/The%20Monthly%20Dirt%20-%20Feb2015.pdf], [https://www.sandiegocounty.gov/content/sdc/dpw/watersheds/IndustrialCommercial/Portable_Toilets.html], [https://www.gwinnettcounty.com/static/departments/publicutilities/pdf/WQ-04%20Portable%20Toilet%20Management-%20Final.pdf], and [http://www.asce-pgh.org/Resources/EWRI/Pathogens%20Paper%20August%202014.pdf]. | ||
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===Other Human Sanitary Sources - Trash cans=== | ===Other Human Sanitary Sources - Trash cans=== | ||
− | + | See the section on [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Other_Human_Sanitary_Sources_-_Dumpsters dumpsters]. Some of the practices suggested in that section will require modification. For example, garbage cans should be tied down to a solid structure so they cannot be overturned, and lids should be tight fitting, tied or weighted down to deny access to garbage. | |
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===Other Human Sanitary Sources - Garbage trucks=== | ===Other Human Sanitary Sources - Garbage trucks=== | ||
− | + | As discussed in the section on [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Other_Human_Sanitary_Sources_-_Dumpsters dumpsters], garbage is a source of bacteria. Trucks transporting this garbage are therefore potential sources of bacteria and pathogens if liquid or solid material escapes the truck. Several cases are documented ([https://scienceblogs.com/terrasig/2008/09/20/e-coli-in-fluid-dripping-from], [https://www.abcactionnews.com/news/local-news/tampa-homeowners-concerned-about-garbage-juice-dumped-along-their-street], [http://www.stormwaterok.net/Documents/News%20Bulletins%20&%20Fact%20Sheets/GCSA%20FS%202013-7%20Leaking%20Garbage%20Trucks.pdf]). | |
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'''Where/when is this a concern'''<br> | '''Where/when is this a concern'''<br> | ||
− | + | The potential for garbage trucks to contribute to bacteria loads in stormwater runoff are greatest where old and/or poorly maintained equipment is used, during transfer of garbage from a dumpster or can to the truck, and where garbage collection staff have not been properly trained or guidance is not in place. | |
'''Management strategies'''<br> | '''Management strategies'''<br> | ||
− | + | New technologies have led to improvements in truck design, including separation of fluids in trucks and sensors. In addition to equipment, proper training of garbage collectors and a garbage management plan or ordinance are effective in minimizing spills and leaks. | |
'''Suggested references'''<br> | '''Suggested references'''<br> | ||
− | + | For more information, see [https://www.gsa.gov/cdnstatic/Waste_Management_Desk_Guide.pdf] and [http://www.stormwaterok.net/Documents/News%20Bulletins%20&%20Fact%20Sheets/GCSA%20FS%202013-7%20Leaking%20Garbage%20Trucks.pdf]. | |
===Domestic pets - Dog parks=== | ===Domestic pets - Dog parks=== | ||
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*Rimming the downslope edge(s) of dog parks with conventional BMPs that show promise at removing bacteria (e.g., infiltration-dependent facilities). | *Rimming the downslope edge(s) of dog parks with conventional BMPs that show promise at removing bacteria (e.g., infiltration-dependent facilities). | ||
− | For more information, see | + | For more information, see [https://www.nps.gov/goga/learn/management/upload/-1565-Dog-Park-bacteria-report.pdf], [http://www.ruekertmielke.com/blog/2018/6/12/improving-storm-water-runoff-at-community-dog-parks], and [https://stormwater.cob.org/tour-squalicum-creek-park/site-dog-park-infiltration-basin/]. |
===Domestic pets - Dogs, cats, etc. residential=== | ===Domestic pets - Dogs, cats, etc. residential=== | ||
− | + | [[File:Dog photo.png|300px|thumb|alt=image of dogs]] | |
− | + | Domestic pets, particularly dogs and to a lesser extent cats, are sources of bacteria in urban environments. Median fecal coliform concentrations in dogs and cats, respectively, are 7.9 and 23 million MPN (most probable number) per g of feces. Other domestic animals include ferrets, pigs, horses, chickens, and goats. In a survey of Chesapeake Bay residents, it was found that about 40% of households own a dog. Just about half of these dog owners actually walked their dog in public areas. Of the half that did walk their dog, about 60% claimed to pick up after their dog. Men were found to be less prone to pick up after their dog than women (State of Rhode Island, Department of Environmental Management). A study in the Minnehaha Creek Watershed, Minnesota, showed that domestic pets were a relatively small contributor to bacteria loads in runoff, likely due to fairly aggressive efforts to have dog owners pick up after their dog. | |
+ | '''Where/when is this a concern'''<br> | ||
+ | The following are reported in the literature. | ||
+ | *In urban areas, concentrations of fecal indicator bacteria in stormwater runoff correlates with higher animal densities and activity | ||
+ | *Bacteria concentrations in runoff are greater in warmer months | ||
+ | *Wet-weather samples have mostly higher enterococci levels than E. coli, while dry weather source area samples (such as springs and irrigation runoff) have higher E. coli levels | ||
+ | *Feral pets, particularly cats, may represent significant sources of bacteria to storm sewers | ||
− | ''' | + | '''Management strategies'''<br> |
+ | A mix of public education and regulations have been shown to be effective in reducing impacts from domestic animals. Education practices focus on relating impacts of pet waste to water quality and include the following. | ||
+ | *Brochures | ||
+ | *Public service announcements | ||
+ | *Signs in public parks | ||
+ | Regulations are largely in the form of ordinances. Regulations should be accompanied by appropriate fines for failing to follow the ordinance. | ||
− | + | In addition to education and regulation, effective practices include establishing waste receptacles and providing dog bags. | |
+ | For information on dog parks, [https://stormwater.pca.state.mn.us/index.php?title=Support_document_for_Checklist_for_bacteria_source_inventory#Domestic_pets_-_Dog_parks link here]. | ||
'''Suggested references'''<br> | '''Suggested references'''<br> | ||
− | + | *[https://dem.ri.gov/ri-stormwater-solutions/take-action/simple-steps/pet-care.php State of Rhode Island, Department of Environmental Management] | |
+ | *[https://megamanual.geosyntec.com/npsmanual/petwastemanagement.aspx Massachusetts Clean Water Toolkit] | ||
===Urban wildlife - Rodents/vectors=== | ===Urban wildlife - Rodents/vectors=== | ||
− | + | This category differs from open space sources primarily due to proximity to the storm sewer system. This includes rats, raccoons, squirrels, opossums and rabbits. These animals often live directly within the storm sewer system or are in frequent contact with directly connected impervious surfaces. They therefore have a high potential for contributing bacteria to stormwater runoff. | |
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+ | '''Where/when is this a concern''' | ||
+ | *Similar to domestic pets, contributions from wildlife occurs primarily during wet weather conditions | ||
+ | *Conditions that attract wildlife, such as poor waste management, easy access to storm sewers, and poor sewer maintenance, increase contributions from these sources | ||
+ | *Some studies suggest there may be seasonal variation in contributions based on animal activity and density | ||
'''Management strategies'''<br> | '''Management strategies'''<br> | ||
− | + | *Minimize conditions likely to attract animals, particularly racoons. Of prime importance is eliminating or minimizing food sources, such as trash cans. | |
+ | *Implement regular maintenance of areas within a storm sewer system likely to attract animals, such as sumps, and junction areas within the system. | ||
+ | *Install storm drain inlet/outlet controls through grates and trash rack. | ||
+ | *If feasible and practical, trap and relocate wildlife. | ||
'''Suggested references'''<br> | '''Suggested references'''<br> | ||
− | + | *[https://www.asce-pgh.org/Resources/EWRI/Pathogens%20Paper%20August%202014.pdf#%5B%7B%22num%22%3A680%2C%22gen%22%3A0%7D%2C%7B%22name%22%3A%22XYZ%22%7D%2C70%2C720%2C0%5D Urban Water Research Council. 2014] | |
− | + | *[https://pubmed.ncbi.nlm.nih.gov/17540431/ Ram et al., 2007] | |
+ | *[https://pubmed.ncbi.nlm.nih.gov/31229001/ Hassel et al., 2019] | ||
===Urban wildlife - Birds/bird congregation areas (gulls, geese, pigeons)=== | ===Urban wildlife - Birds/bird congregation areas (gulls, geese, pigeons)=== | ||
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==Related pages== | ==Related pages== | ||
+ | |||
+ | <noinclude> | ||
+ | [[Category:Level 2 - Pollutants/Bacteria and pathogens]] | ||
+ | </noinclude> |
The MPCA, working with stakeholders, developed a checklist for conducting an inventory of bacteria sources. The checklist is not a permit requirement but may be used to meet permit requirements 22.3 and 22.4. This page provides guidance and supporting information for the checklist.
Link to the checklist: File:Checklist for bacteria source inventory.xlsx
The checklist contains four worhsheets.
These are discussed below.
This sheet provides basic general information about the checklist.
This is the sheet where users enter information. Column A contains different categories of bacteria sources and specific sources within each category. The categories include the following.
Columns B through G are where users input information.
Filling out this checklist fulfills permit requirements 22.3 and 22.4, as long as Columns B, C, D and E are completed and the source locations are mapped. However, if the sources are not mapped, then an inventory (i.e. addresses of bacteria source locations) needs to be documented.
This section provides some basic information about each of the potential sources included in the checklist. Where appropriate we include links where additional information can be found.
Runoff from impervious surfaces typically contains high concentrations of bacteria. The impervious surface, however, is not the source of the bacteria; it is the conveyance mechanism.
Ultimately the source of bacteria in urban stormwater is animal waste. Identifying the specific source is more challenging and likely varies with location and land use. Typical sources include domestic pets and wildlife, particularly birds. Sources of bacteria to receiving waters include urban stormwater runoff, leaking sewer lines, sewer overflows, septic systems, landfills, marinas and pumpout facilities, poorly operating packing plants, and other illicit discharges.
Some general observations from the literature are summarized below.
Land use | Median (MPN/ml) | Maximum (MPN/ml) |
---|---|---|
Commercial | 6900 | 350000 |
Industrial | 9700 | 290000 |
Residential | 20000 | 600000 |
Rooftop | 1250 | |
Open space | 4500 | |
Forested | < 100 |
Sewage typically contains fecal coliform concentrations in excess of one million most probable number per 100 milliliter (MPN/100 ml). This is about two orders of magnitude greater than urban stormwater concentrations. General indicators of bacteria sources include the following.
A complicating factor is that bacteria can survive and grow both within the storm sewer system and within receiving waters. Growth within the storm sewer systems includes both the surface and subsurface conveyances. For example, coliform bacteria have been found to survive and grow in moist soils and leaf piles. A recent study in Minneapolis indicated that catch basins are an important source, largely as a result of growth within the catch basin.
The following table provides a summary of data from the literature. Maximum concentrations are included to illustrate the tremendous variability that may occur in bacteria concentrations. The values represent a compilation of data from several sources (see references at the bottom of this page).
The following links go to tables providing management strategies for different bacteria sources.
RV dumping or leaking into the storm drains, particularly at vacation destinations, can contribute bacteria and pathogens to the storm sewer system, either by directly dumping into storm drains or by dumping onto impermeable surfaces that drain to the storm sewer system. Illicit RV dumping can be managed by providing public education on appropriate practices, publicizing RV dump locations, by proving a citizen’s reporting hotline, and by publicizing fines (PATHOGENS in Urban Stormwater Systems). For an example of an RV dumping brochure, see the brochure “Think Blue San Diego”.
Street litter and plant material indirectly contribute to bacteria loads by providing a food source and habitat for bacteria populations to survive and grow. A study in the Minnehaha Creek Watershed, Minnesota, indicated organic material is an important contributor to bacteria in stormwater runoff.
There are few studies that specifically focus on street debris as a source for bacteria. This is likely to be an important source during times of the year when organic debris is in streets and temperatures and moisture conditions are conducive to bacterial growth. Spring and early fall are therefore the most likely times for this to be an important source of bacteria.
Pollution prevention and source control practices, such as street sweeping, are recommended to control street litter and plant material. This table provides a summary of additional practices for residential areas, many designed to control sources of organic material to the storm sewer system.
The United States Environmental Protection Agency defines an illicit discharge as, “any discharge into a storm drain system that is not composed entirely of stormwater.” The Minnesota Municipal Separate Storm Sewer System (MS4) General Permit defines illicit discharge as any discharge to a municipal separate storm sewer that is not composed entirely of stormwater except discharges pursuant to a NPDES permit (other than the NPDES permit for discharges from the municipal separate storm sewer) and discharges resulting from firefighting activities.
There are many potential illicit discharges to an MS4. The concern here are sources that contribute bacteria and pathogens, or that contribute pollutants that may promote bacteria and pathogen growth (e.g. organic sources). The most important potential sources are likely to be sanitary sewer connections, including broken sanitary sewer lines where septage seeps into a storm sewer line, cross-connections, and and straight pipe discharges. These sources contribute high concentrations of bacteria and pathogens to the storm sewer system.
Stormwater practitioners and managers covered under the MS4 General permit must develop and implement an illicit discharge detection and elimination (IDDE) program. Information on permit requirements is found here.
Many illicit discharges occur during dry weather when storm flows are not contributing, or are intermittent. This may aid in detecting illicit discharges, since storm sewer discharges during dry weather or intermittent discharges may indicate the presence of illicit discharges. There are several techniques for detecting illicit discharges, including outfall monitoring, use of tracers (e.g. smoke, dye), and use of electronic equipment (e.g. cameras). More specific information on some illicit discharges and methods for identifying them are found in the sections oncombined sewer overflows, sanitary sewer overflows, inflow and infiltration, and illicit connections to sanitary sewers.
For more information, see the following documents.
Irrigation runoff is an allowed discharge to storm sewer systems, provided there are no illicit pollutants in the discharge. Irrigation runoff can contribute bacteria and pathogens to runoff and mobilize sources within the storm sewer system. In particular, irrigation runoff is a potentially important source of dry weather flows in residential and commercial areas. A study in the Minnehaha Creek Watershed, Minnesota, indicated over-irrigation and subsequent runoff from lawns was an important source of bacteria.
A study in San Diego indicated a higher frequency of runoff in residential areas compared to commercial land uses. An Alabama study indicated wet-weather samples having mostly higher enterococci levels than E. coli, while dry weather source area samples (such as springs and irrigation runoff) had higher E. coli levels (Shergill and Pitt, 1984). The contribution of dry weather inflows from irrigation runoff has also been known to foster in-situ bacterial growth (Geosyntec 2010).
The primary focus on reducing inputs from irrigation should focus on reducing overirrigation. Effective methods to reduce irrigation runoff include development of educational outreach, increased inspections, fines for overwatering, tiered water rates, provide irrigation controller rebates or distribution of smart irrigation controllers and/or other financial incentive programs that decrease watering volume (Geosyntec 2012). A residential runoff study in Orange County conducted in five neighborhoods found dryweather runoff decreased by 50% in areas where weather-based irrigation controllers were installed (IRWD and OCMWD 2004). Berg et al. (2009) found dry-weather runoff reductions of 25% to 50% for a similar study of 4,100 Smart Timers installed in residential and commercial areas. Promoting better irrigation runoff management also reduces water waste and can improve water quality.
Regrowth of bacteria in the storm sewer system has been documented but is poorly understood. Regrowth is problematic because it may negate upstream efforts to control bacteria and pathogens.
Regrowth typically occurs in biofilms. Biofilms are surface-attached communities of microorganisms that undergo cell attachment, growth, detachment, and sloughing. Biofilms are normally extremely diverse and include a wide variety of bacteria, including pathogenic bacteria. The pathogens E. coli O157:H7, Salmonella enterica, and Campylobacter jejuni are all known to form biofilms. Further, biofilm formation can favor the survival of all three of these organisms under both typical environmental conditions and under active disinfection. Biofilms act as a source of bacteria in stormwater runoff during periods of higher flow, which dislodges bacteria from the biofilms.
Factors that commonly limit the survival of bacterial pathogens in biofilms include low levels of available nutrients and organic material, non-favorable oxygen concentrations, and the competitive, antagonistic and predatory activities of the indigenous microbial population. High stormflow rates cause detachment and sloughing of biofilms. Biofilms can develop in urban storm sewer piping and in streets. Some researchers have questioned the utility of using indicator bacteria in conditions favorable for biofilm growth, since indicator bacteria survive and grown in biofilms while many pathogenic bacteria do not.
Irrigation runoff can contribute to formation of biofilms in storm sewers that can be an on-going source of bacteria discharged from the storm sewer system Green Infrastructure Implementation Strategy (2018). Other factors that may favor biofilm development include organic debris in streets, favorable surfaces for attachment within the storm sewer system (e.g. submerged aprons, particularly those constructed of concrete), and increased loading with natural sediments containing naturally occurring biofilms, stormwater enriched in bacteria. During prolonged periods between runoff events, environmental biofilms (i.e. naturally-occurring) appear to outcompete and replace biofilms consisting of bacteria originating from stormwater flows. Enhancing the storm sewer environment to favor environmental bacteria may be one approach to reducing loading of bacteria from stormwater flows.
For more information, see Urban Water Resources Research Council (2014), Roberts (2012), and Burkhart (2013).
Leaky sewer pipes potentially can contribute very high concentrations of bacteria to storm sewer systems.
Leaking sewer systems are more common in areas with aging infrastructure, where contributions from leaking systems can be as high as 20 percent of annual flow in the sanitary sewer system. For a detailed discussion of contributions from leaking sewer systems, see Sercu et al. (2011), Vasquez-Sune et al. (2011), Yang et al. (1999), Rutsch (2006), and Prigiobbe and Giulianelli (2011).
For more information on potential effects of leaking sewer infrastructure, methods of detecting leaks, and management strategies, see the section on illicit discharges and the section on sanitary sewer inflow and infiltration.
Permeable surfaces contribute to runoff when the rate of water application from precipitation, melting snow, or irrigation exceeds the infiltration capacity of the soil. Factors contributing to runoff from permeable surfaces include compacted soils, soils with naturally low infiltration rates (e.g D soils), saturated soils, frozen soils, and soils subject to over-irrigation. Sources of bacteria to permeable surfaces include birds, small mammals, dogs, etc.
Urban lawns and other grass areas can be a source of bacteria and pathogens to stormwater runoff. Concentrations of indicator bacteria in runoff typically exceed water quality standards in all land uses, often by more than an order of magnitude, with concentrations tending to be higher from residential areas compared to commercial, industrial, and open space land uses (Minnesota Stormwater Manual). Grass swales and grass strips typically have higher concentrations of bacteria and enterococci in outflow water compared to inflow, although if these practices infiltrate water the total loading may be decreased by the practices (International BMP Database). Contributions of bacteria to runoff from grass areas is not well understood. Hathaway and Hunt (2010) conducted a study of bacteria in runoff from residential areas in North Carolina and concluded the following.
Practices or factors that potentially contribute to bacteria loading from grass areas include the following.
Practices to reduce bacteria inputs from grass areas include the following.
Combined sewer systems (CSS) are sewers that are designed to collect rainwater runoff, domestic sewage, and industrial wastewater in the same pipe. When the capacity of the CSS is exceeded, excess water can bypass treatment and bypassed flow will be mixed with the treated water prior to disinfection and just prior to discharge to the receiving water. While both stormwater runoff and sanitary sewer discharges contain bacteria, concentrations are much higher in untreated sewage. Thus, CSOs can lead to very high concentrations of bacteria in water delivered to receiving waters.
Where/when is this a concern During wet weather conditions, the volume of stormwater runoff can exceed the capacity of the CSS infrastructure, including both the piping system and/or the treatment plant. This is common where where older CSS infrastructure is in place, combining sanitary and storm drain flows.
Where feasible, CSOs should be separated so that the different water sources do not mix. Because this is typically cost prohibitive, separation can be done strategically in steps, identifying high priority areas and retrofitting those first. Implementing stormwater runoff capture and infiltration may reduce the CSO problem by decreasing stormflow volumes. Diversions or upgrades to water treatment facilities are other options.
For more information, see [3], [4], [5], [6].
Sanitary sewer systems collect and transport domestic, commercial, and industrial wastewater. Some sanitary sewer systems may contain limited amounts of stormwater and infiltrated ground water to treatment facilities, but they are designed to carry just sewage and industrial wastewater. Occasionally, sanitary sewers will release raw sewage. These types of releases are called sanitary sewer overflows (SSOs). SSOs that discharge to surface waters are considered point source discharges and are thus prohibited unless authorized by a NPDES permit. SSOs may be indicative of improper operation and maintenance of the sewer systems, and may violate NPDES permit conditions.
Where/when is this a concern
Possible causes of SSOs include blockages, line breaks, sewer defects that allow stormwater and groundwater to overload the system, power failures, improper sewer design, and vandalism. The adjacent image indicates line blockages appear to be an important cause of SSOs. An EPA survey indicated SSOs are most common during wet weather flows.
Management strategies
Effective illicit discharge and elimination practices and programs minimize the occurrence and impacts from SSOs. Other management strategies include the following.
Suggested references
For more information, see [7], [8], [9], [10]
Groundwater infiltration and rainfall derived inflow and infiltration, commonly referred to as inflow, are components of most sanitary sewer systems. These inputs, called I&I, should be a minor component of the sanitary sewer flow. However, infiltration and inflow may be considered excessive when it is the cause of overflows (SSO) or bypasses in the sanitary sewer system. In addition, I&I is treated at wastewater treatment plants even though it is relatively clean water, resulting in extra cost.
Where/when is this a concern
EPA provides guidance for estimating the input and importance of I&I in a sanitary sewer system. To assess extraneous water entering your system at least a year of influent flow data to the treatment facility should be examined. For infiltration analysis, flow data collected during the high groundwater periods is used. For inflow analysis, the Average Wet Weather (AWW) flow can be estimated from flow data for a
one week period when there has been significant rain. If a single storm event is used to analyze wet weather inflow, it should be an event large enough to cause surface ponding and runoff. Other techniques can be used to determine the presence of I&I, including manhole testing and maintenance, dye tracing, smoke testing, use of cameras, and private property inspection for improper connections. Examples of improper connections include downspouts, groundwater sump pumps, foundation drains, drains from window wells and outdoor basement stairwells and drains from driveways.
Management strategies
Proper evaluation of I&I sources is necessary to manage them. Once detected, they can be eliminated or minimized. Several cities, for example, have programs and ordinances prohibiting illicit connections on private property.
Suggested references
For more information, see [11], [12], [13], [14]
The Municipal Separate Storm Sewer System (MS4) General Permit defines illicit discharge as "any discharge to a municipal separate storm sewer that is not composed entirely of stormwater except discharges pursuant to a NPDES permit (other than the NPDES permit for discharges from the municipal separate storm sewer) and discharges resulting from firefighting activities". Not all illicit discharges contain bacteria and pathogens, but examples of illicit discharge sources containing bacteria and pathogens include sewage and septage, washwater, irrigation water, and some commercial and industrial water.
Where/when is this a concern
Illicit discharges to the storm sewer system can be classified as direct or indirect. Direct discharges are directly connected to the storm drain pipe through a sewage pipe, shop drain, or other kind of pipe. Direct discharges are typically continuous or intermittent and occur when two different kinds of “plumbing” are improperly connected. The three main situations where this occurs are sewage cross-connections, straight pipes, and industrial and commercial cross-connections. Indirect discharges are generated outside the storm drain system and enter through storm drain inlets or by infiltrating through the joints of the pipe. Generally, indirect discharges are intermittent or transitory, with the exception of groundwater seepage. Indirect discharges include groundwater seepage, spills, dumping, outdoor washing, and irrigation.
Certain types of illicit discharges can be associated with specific land uses. For example, failing septic systems and irrigation sources are more common in residential areas, while in commercial areas important sources include washing, dumping, and spills. This EPA document provides a table and discussion of likely sources for different land uses.
Management strategies
For entities covered under municipal NPDES stormwater permits, Minimum Control Measure 3 requires establishment and maintenance of an illicit discharge detection and elimination (IDDE) program. The permit contains specific items that are required as part of an IDDE program.
Techniques for detecting illicit discharges include techniques for detecting infiltration and inflow. These include monitoring, dye tracing, smoke detection, use of camera, and focused inspections.
Suggested references
For more information see [15], [16], [17].
Where/when is this a concern
If properly placed and maintained, porta potties should not be a source of bacteria to the stormwater system. However, they have the potential to contribute high concentrations of bacteria and pathogens. In addition, cleaning of portable toilets may contribute other pollutants, such as disinfectants, to runoff.
Management strategies
There are numerous fact sheets and guidance documents concerning porta potties. Some useful links are provided below. Common practices for properly managing porta potties include the following.
Suggested references
For more information, see [18], [19], [20], and [21].
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Dumpsters may contain materials that are direct sources of bacteria and pathogens (e.g. diapers, pet waste bags) and may attract wildlife that contribute bacteria and pathogens. Leaking dumpsters can therefore be a source of bacteria to the stormwater system. Concentrations of bacteria are typically very high from dumpsters, particularly from dumpster washdowns, which can constitute an important dry weather source of bacteria.
Practices to reduce bacteria from dumpsters include the following.
For more information see [22], [23], [24], and [25].
See the section on dumpsters. Some of the practices suggested in that section will require modification. For example, garbage cans should be tied down to a solid structure so they cannot be overturned, and lids should be tight fitting, tied or weighted down to deny access to garbage.
As discussed in the section on dumpsters, garbage is a source of bacteria. Trucks transporting this garbage are therefore potential sources of bacteria and pathogens if liquid or solid material escapes the truck. Several cases are documented ([26], [27], [28]).
Where/when is this a concern
The potential for garbage trucks to contribute to bacteria loads in stormwater runoff are greatest where old and/or poorly maintained equipment is used, during transfer of garbage from a dumpster or can to the truck, and where garbage collection staff have not been properly trained or guidance is not in place.
Management strategies
New technologies have led to improvements in truck design, including separation of fluids in trucks and sensors. In addition to equipment, proper training of garbage collectors and a garbage management plan or ordinance are effective in minimizing spills and leaks.
Suggested references
For more information, see [29] and [30].
Dog parks represent an obvious potential source of bacteria and pathogens. Recommended practices for minimizing bacteria loading from dog parks include the following.
For more information, see [31], [32], and [33].
Domestic pets, particularly dogs and to a lesser extent cats, are sources of bacteria in urban environments. Median fecal coliform concentrations in dogs and cats, respectively, are 7.9 and 23 million MPN (most probable number) per g of feces. Other domestic animals include ferrets, pigs, horses, chickens, and goats. In a survey of Chesapeake Bay residents, it was found that about 40% of households own a dog. Just about half of these dog owners actually walked their dog in public areas. Of the half that did walk their dog, about 60% claimed to pick up after their dog. Men were found to be less prone to pick up after their dog than women (State of Rhode Island, Department of Environmental Management). A study in the Minnehaha Creek Watershed, Minnesota, showed that domestic pets were a relatively small contributor to bacteria loads in runoff, likely due to fairly aggressive efforts to have dog owners pick up after their dog.
Where/when is this a concern
The following are reported in the literature.
Management strategies
A mix of public education and regulations have been shown to be effective in reducing impacts from domestic animals. Education practices focus on relating impacts of pet waste to water quality and include the following.
Regulations are largely in the form of ordinances. Regulations should be accompanied by appropriate fines for failing to follow the ordinance.
In addition to education and regulation, effective practices include establishing waste receptacles and providing dog bags.
For information on dog parks, link here.
Suggested references
This category differs from open space sources primarily due to proximity to the storm sewer system. This includes rats, raccoons, squirrels, opossums and rabbits. These animals often live directly within the storm sewer system or are in frequent contact with directly connected impervious surfaces. They therefore have a high potential for contributing bacteria to stormwater runoff.
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This page was last edited on 25 February 2023, at 03:27.