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The construction and operation of stormwater harvest and use systems can pose potential risks from the pollutants and toxins found in stormwater and harvest and use system materials. These risks are largely addressed via water quality standards, plumbing and building codes, stormwater rules and regulations, required signage, and the engineering review process. Stormwater harvesting is, however, an emerging practice in water resource management and existing regulations may not fully address the risks associated with harvest and use practices. | The construction and operation of stormwater harvest and use systems can pose potential risks from the pollutants and toxins found in stormwater and harvest and use system materials. These risks are largely addressed via water quality standards, plumbing and building codes, stormwater rules and regulations, required signage, and the engineering review process. Stormwater harvesting is, however, an emerging practice in water resource management and existing regulations may not fully address the risks associated with harvest and use practices. | ||
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===Managing risk=== | ===Managing risk=== | ||
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Potential risks must be managed through proper design, operation, and maintenance of stormwater harvesting systems-see table below. If potential risks cannot be addressed through cost-effective [http://stormwater.pca.state.mn.us/index.php/Design_criteria_for_stormwater_and_rainwater_harvest_and_use/reuse design] or [http://stormwater.pca.state.mn.us/index.php/Operation_and_maintenance_for_stormwater_and_rainwater_harvest_and_use/reuse operation and maintenance], the goals and objectives of the stormwater harvest and use system should be reconsidered in the [http://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_stormwater_and_rainwater_harvest_and_use/reuse&action=edit§ion=3 pre-design phase]. | Potential risks must be managed through proper design, operation, and maintenance of stormwater harvesting systems-see table below. If potential risks cannot be addressed through cost-effective [http://stormwater.pca.state.mn.us/index.php/Design_criteria_for_stormwater_and_rainwater_harvest_and_use/reuse design] or [http://stormwater.pca.state.mn.us/index.php/Operation_and_maintenance_for_stormwater_and_rainwater_harvest_and_use/reuse operation and maintenance], the goals and objectives of the stormwater harvest and use system should be reconsidered in the [http://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_stormwater_and_rainwater_harvest_and_use/reuse&action=edit§ion=3 pre-design phase]. | ||
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===Key resources=== | ===Key resources=== | ||
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*Chapter 5-Characterization and mitigating human health and environmental risks in: The National Academies of Sciences, Engineering, and Medicine (NAS). 2016. [https://www.nap.edu/read/21866/chapter/7 Using Graywater and Stormwater to Enhance Local Water Supplies: An Assessment of Risks, Costs, and Benefits]. Washington, DC: The National Academies Press. | *Chapter 5-Characterization and mitigating human health and environmental risks in: The National Academies of Sciences, Engineering, and Medicine (NAS). 2016. [https://www.nap.edu/read/21866/chapter/7 Using Graywater and Stormwater to Enhance Local Water Supplies: An Assessment of Risks, Costs, and Benefits]. Washington, DC: The National Academies Press. | ||
*United States Environmental Protection Agency. [https://www.epa.gov/risk Risk Assessment Webpage]. | *United States Environmental Protection Agency. [https://www.epa.gov/risk Risk Assessment Webpage]. | ||
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*Natural Resource Management Ministerial Council, Environment Protection and Heritage Council, and National Health and Medical Research Council. 2008. [http://www.environment.gov.au/system/files/resources/9e4c2a10-fcee-48ab-a655-c4c045a615d0/files/water-recycling-guidelines-augmentation-drinking-22.pdf Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 2) - Stormwater Harvesting and Reuse]. | *Natural Resource Management Ministerial Council, Environment Protection and Heritage Council, and National Health and Medical Research Council. 2008. [http://www.environment.gov.au/system/files/resources/9e4c2a10-fcee-48ab-a655-c4c045a615d0/files/water-recycling-guidelines-augmentation-drinking-22.pdf Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 2) - Stormwater Harvesting and Reuse]. | ||
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+ | ==Related pages== | ||
*[[Overview for stormwater and rainwater harvest and use/reuse]] | *[[Overview for stormwater and rainwater harvest and use/reuse]] | ||
*[[Design criteria for stormwater and rainwater harvest and use/reuse]] | *[[Design criteria for stormwater and rainwater harvest and use/reuse]] | ||
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*[[Calculating credits for stormwater and rainwater harvest and use/reuse]] | *[[Calculating credits for stormwater and rainwater harvest and use/reuse]] | ||
*[[Definitions for stormwater and rainwater harvest and use/reuse]] | *[[Definitions for stormwater and rainwater harvest and use/reuse]] | ||
+ | *[https://stormwater.pca.state.mn.us/index.php?title=Requirements,_recommendations_and_information_for_using_Harvest_and_re-use/cistern_as_a_BMP_in_the_MIDS_calculator Requirements, recommendations and information for using Harvest and re-use/cistern as a BMP in the MIDS calculator] | ||
*[[Links for stormwater and rainwater harvest and use/reuse]] | *[[Links for stormwater and rainwater harvest and use/reuse]] | ||
*[[References for stormwater and rainwater harvest and use/reuse]] | *[[References for stormwater and rainwater harvest and use/reuse]] | ||
*[[Technical support for stormwater and rainwater harvest and use/reuse]] | *[[Technical support for stormwater and rainwater harvest and use/reuse]] | ||
+ | </noinclude> |
The construction and operation of stormwater harvest and use systems can pose potential risks from the pollutants and toxins found in stormwater and harvest and use system materials. These risks are largely addressed via water quality standards, plumbing and building codes, stormwater rules and regulations, required signage, and the engineering review process. Stormwater harvesting is, however, an emerging practice in water resource management and existing regulations may not fully address the risks associated with harvest and use practices.
Therefore, a risk assessment should be completed during the pre-design phase to ensure that potential risks are properly managed through system design, operation and maintenance. According to U.S. EPA, there are two types of risk assessments:
The following factors should be considered when assessing human health and ecological risks of stormwater harvesting and use systems (NAS, 2016):
Potential human health and environmental risks of stormwater harvest and use systems, and ways to manage those risks through design, operation and maintenance are summarized briefly below. For further guidance, refer to Chapter 5 of Using Graywater and Stormwater to Enhance Local Water Supplies: An Assessment of Risks, Costs, and Benefits (NAS, 2016) and the US EPA Risk Assessment webpage.
Specific guidelines for addressing health and environmental risks associated with stormwater harvest and use systems have been developed in Australia. See Figure 1.1 on page 6 of the Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 2), Stormwater Harvesting and Reuse for a flow-diagram guide to their risk assessment approach.
Human health risks include any adverse health effects in humans who may be exposed to chemicals in contaminated environmental media, now or in the future. Potential hazards to human health from stormwater harvest and use systems include:
The main health concern with harvest and use of stormwater is exposure to pathogenic microorganisms. Studies have consistently reported high concentrations of fecal indicator microorganisms across different source areas of stormwater; however, the occurrence and fate of human pathogens in stormwater is not well characterized (NAS, 2016). The nature and severity of human health effects depend on the type of exposure (skin contact, ingestion, inhalation, etc.) as well as the duration and magnitude of exposure (Table 1). Treatment requirements will be stricter for beneficial use applications which have a high chance of exposure compared to those which have a low risk of exposure. Additional information on exposure and dose-response assessments can be found on the EPA Human Health Risk Assessment webpage. This webpage also provides detailed guidance on how to complete the following steps of a human health risk assessment:
Examples of potential exposure types and pathways
Link to this table
Exposure Types | Exposure Pathways |
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Skin contact |
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Direct ingestion |
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Indirect ingestion |
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Inhalation |
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Ecological risks include any impact on the environment from the result of exposure to one or more environmental stressors such as chemicals, land change, disease, invasive species and climate change. Potential ecological risks from stormwater harvest and use systems include impacts to the following.
Potential risks must be managed through proper design, operation, and maintenance of stormwater harvesting systems-see table below. If potential risks cannot be addressed through cost-effective design or operation and maintenance, the goals and objectives of the stormwater harvest and use system should be reconsidered in the pre-design phase.
Elements of design, operation, and maintenance that address potential risks associated with stormwater harvesting and use
Link to this table
Risk Type | Design Considerations | O & M Considerations |
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Human Health Risks | ||
Source area pollutants |
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Hazardous spills in the source area, including sudden air releases of hazardous substances that could deposit in the collection and storage systems |
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Metals and other chemicals from roofing materials (link to table 4 in WQ considerations) |
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Bacteria, viruses |
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Mosquito and other vector-borne illnesses |
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Ecological Risks | ||
Plant communities |
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Soils |
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Aquatic ecosystems |
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Local hydrology |
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Equipment degradation |
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