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==Green Infrastructure benefits of harvest and reuse systems== | ==Green Infrastructure benefits of harvest and reuse systems== | ||
− | *Water quality: Installation of harvest and reuse systems prevents or reduces a sites’ total pollution runoff amount | + | *[https://stormwater.pca.state.mn.us/index.php?title=Water_quality_benefits_of_Green_Stormwater_Infrastructure '''Water quality''']: Installation of harvest and reuse systems prevents or reduces a sites’ total pollution runoff amount |
**Reduces downstream water treatment levels when water is stored on site | **Reduces downstream water treatment levels when water is stored on site | ||
**Wastewater treatment requirements may be reduced due to the incorporation of reuse systems that use on site water for functions such as urinal flushing, water features, and sprinkler systems | **Wastewater treatment requirements may be reduced due to the incorporation of reuse systems that use on site water for functions such as urinal flushing, water features, and sprinkler systems | ||
− | *Water quantity and hydrology: | + | *[https://stormwater.pca.state.mn.us/index.php?title=Water_quantity_and_hydrology_benefits_of_Green_Stormwater_Infrastructure '''Water quantity and hydrology''']: |
**Reduction in total water volume movement on the site through water retention techniques and retardation of peak flow from rainfall events at the site | **Reduction in total water volume movement on the site through water retention techniques and retardation of peak flow from rainfall events at the site | ||
**Harvest and reuse systems designed with storage containers are better able to withstand drought conditions than sites without them (Costs, Benefits, or Function? What Really Drives Water Reuse) | **Harvest and reuse systems designed with storage containers are better able to withstand drought conditions than sites without them (Costs, Benefits, or Function? What Really Drives Water Reuse) | ||
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**Harvest and reuse systems provide indirect energy savings through reduced water treatment and distribution required by outside sources | **Harvest and reuse systems provide indirect energy savings through reduced water treatment and distribution required by outside sources | ||
**Harvest and reuse systems used to irrigate vegetation that provide shade, trees and plants, reduce air conditioning and heating costs (Using Trees and Vegetation to Reduce Heat Islands | US EPA) | **Harvest and reuse systems used to irrigate vegetation that provide shade, trees and plants, reduce air conditioning and heating costs (Using Trees and Vegetation to Reduce Heat Islands | US EPA) | ||
− | *Air quality: | + | *[https://stormwater.pca.state.mn.us/index.php?title=Air_quality_benefits_of_Green_Stormwater_Infrastructure '''Air quality''']: |
**Air quality impact is minimal, most benefits are indirect through vegetation grown by the harvest and reuse system | **Air quality impact is minimal, most benefits are indirect through vegetation grown by the harvest and reuse system | ||
− | *Climate resiliency | + | *[https://stormwater.pca.state.mn.us/index.php?title=Climate_benefits_of_Green_Stormwater_Infrastructure '''Climate resiliency''']: |
**Site water containment in harvest and reuse systems offers some reduction in flooding during rainfall events | **Site water containment in harvest and reuse systems offers some reduction in flooding during rainfall events | ||
**Plant vegetation grown with reuse irrigation systems provide carbon sequestration | **Plant vegetation grown with reuse irrigation systems provide carbon sequestration | ||
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**Lower greenhouse gas emissions through reduced air conditioner use (Report Finds Onsite Water Reuse Can Boost Affordable Housing, Spread Climate Resilience – Texas Living Waters Project) | **Lower greenhouse gas emissions through reduced air conditioner use (Report Finds Onsite Water Reuse Can Boost Affordable Housing, Spread Climate Resilience – Texas Living Waters Project) | ||
**The promotion of vegetation and biota growth, vegetative filtering, soil adsorption, and gravitational settling of pollutants that would otherwise be moved by rainfall events and create toxic blooms such as the algae blooms in the Gulf of Mexico | **The promotion of vegetation and biota growth, vegetative filtering, soil adsorption, and gravitational settling of pollutants that would otherwise be moved by rainfall events and create toxic blooms such as the algae blooms in the Gulf of Mexico | ||
− | *Habitat improvement | + | *[https://stormwater.pca.state.mn.us/index.php?title=Wildlife_habitat_and_biodiversity_benefits_of_Green_Stormwater_Infrastructure '''Habitat improvement''']: |
**Reduction of soil erosion from water runoff and increased soil stability promotes vegetation growth | **Reduction of soil erosion from water runoff and increased soil stability promotes vegetation growth | ||
**Less of a temperature impact to streams and rivers that receive water discharge and serve as fish and wildlife habitats | **Less of a temperature impact to streams and rivers that receive water discharge and serve as fish and wildlife habitats | ||
− | *Community livability | + | *[https://stormwater.pca.state.mn.us/index.php?title=Social_benefits_of_Green_Stormwater_Infrastructure '''Community livability''']: |
**Harvest and reuse systems help to protect recreation sites for people by ensuring safe and healthy access to water sources and promotes on-site watering availability | **Harvest and reuse systems help to protect recreation sites for people by ensuring safe and healthy access to water sources and promotes on-site watering availability | ||
**Water harvest and reuse are adaptable to meet needs such as community gardening, water fountain structures, promoting healthy green spaces, and may be used for recreation purposes if water quality requirements are met | **Water harvest and reuse are adaptable to meet needs such as community gardening, water fountain structures, promoting healthy green spaces, and may be used for recreation purposes if water quality requirements are met | ||
**Water harvesting and reuse that promotes healthy landscaping can promote mental health improvements for those who frequent them (What are the physical and mental benefits of gardening? - MSU Extension) | **Water harvesting and reuse that promotes healthy landscaping can promote mental health improvements for those who frequent them (What are the physical and mental benefits of gardening? - MSU Extension) | ||
**Larger reuse systems involved with irrigation practices involving trees and other shade proving vegetation reduce temperature levels (Reducing Urban Heat Islands: Compendium of Strategies: Trees and Vegetation (epa.gov)) | **Larger reuse systems involved with irrigation practices involving trees and other shade proving vegetation reduce temperature levels (Reducing Urban Heat Islands: Compendium of Strategies: Trees and Vegetation (epa.gov)) | ||
− | *Health benefits: | + | *[https://stormwater.pca.state.mn.us/index.php?title=Social_benefits_of_Green_Stormwater_Infrastructure '''Health benefits''']: |
**Reduction of downstream buildup of nutrients, pathogens, metals, TSS, and phosphorus among others as an indirect, off site benefit | **Reduction of downstream buildup of nutrients, pathogens, metals, TSS, and phosphorus among others as an indirect, off site benefit | ||
**Increased longevity for fish and wildlife in the area through the reduction of compounds that wash into waterways as rain runoff | **Increased longevity for fish and wildlife in the area through the reduction of compounds that wash into waterways as rain runoff |
Harvest and reuse is the practice of collecting and/or storing stormwater on site to be used in water applications as needed. Harvest and reuse systems use collected water from various sources, treats them, and then reuses this water on site for different purposes such as irrigation or water features. This practice mitigates the users cost for water, reduces the site's stormwater runoff, and prevents pollution runoff.
Sites containing these systems are not regulated by the EPA but may be regulated by the state through the Safe Drinking Water Act or the Clean Water Act. Water harvest and reuse systems are regulated in Minnesota by Minnesota Rules Section 4714, chapter 17.
Rainwater harvesting is categorized into two types of harvest:
Both categories of rainwater harvesting follow the same principles for stormwater reuse. When the rainwater falls onto the site the water is collected through a series of conveyance systems into a storage system, the water is then treated and stored, and the user applies it to their site through a distribution system for the designed purpose. Some designed purposes include;
Harvest and reuse systems are excellent stormwater treatment practices due to the pollutant removal mechanisms they can be paired with such as vegetative filtering, settling, evaporation, infiltration, transpiration, biological and microbiological uptake, and soil adsorption. Additionally, the pollutants stay on site instead of being flushed downstream. These systems are particularly effective when used for irrigation on C and D soils where traditional infiltration practices are less effective.
Benefit | Effectiveness | Notes |
---|---|---|
Water quality | Can be used in a variety of settings, including low permeability soils. | |
Water quantity/supply | Benefit depends on the amount of water that can be stored. Use of ponds or multiple dispersed systems can provide significant volume reduction. | |
Energy savings | Savings associated with reductions in potable water usage. | |
Climate resiliency | Depending on design, may provide energy and water savings. | |
Air quality | ||
Habitat improvement | Benefits are associated with how the system is used (e.g. in vegetated applications). | |
Community livability | Provides water-related benefits; can be used for indoor applications. | |
Health benefits | ||
Economic savings | Cost savings associated with water use and decreased use of potable water. | |
Macroscale benefits | Individual practices are typically microscale, but multiple practices, when incorporated into a landscape design, can provide macroscale benefits. | |
Level of benefit: ◯ - none; ◔ - small; ◑ - moderate; ◕ - large; ● - very high |
Green infrastructure (GI) encompasses a wide array of practices, including stormwater management. Green stormwater infrastructure (GSI) encompasses a variety of practices primarily designed for managing stormwater runoff but that provide additional benefits such as habitat or aesthetic value.
There is no universal definition of GI or GSI (link here fore more information). Consequently, the terms are often interchanged, leading to confusion and misinterpretation. GSI practices are designed to function as stormwater practices first (e.g. flood control, treatment of runoff, volume control), but they can provide additional benefits. Though designed for stormwater function, GSI practices, where appropriate, should be designed to deliver multiple benefits (often termed "multiple stacked benefits". For more information on green infrastructure, ecosystem services, and sustainability, link to Multiple benefits of green infrastructure and role of green infrastructure in sustainability and ecosystem services.
Maximizing specific green infrastructure (GI) benefits of constructed areas requires design considerations prior to installation. While site limitations cannot always be overcome, the following recommendations are given to maximize the GI benefit of water harvesting and reuse.
Note: Harvest and reuse systems are a good stormwater treatment practice when used in a treatment train. Under the Minnesota Construction Stormwater Permit GI, if Class D soils are present on the site infiltration practices cannot be used. Class A soils are the most desirable for infiltration but infiltration can also be successful with B or C soils. These notes are not mandates nor are they a complete list of what is the best practice for each site, site consideration needs will be addressed by the building design team.
--- Maybe add a chart indicating soil penetrability of different HSG groups —
The Pollution Control Agency allows for infiltration to be used as a credit source when meeting pollutant budgets for Total Suspended Solids (TSS) and Total Phosphorus (TP). The methodology for counting credits can be found here.
Additional Information: Water harvest and reuse systems are effective for use in class C and D soils Harvest and reuse systems can be incorporated in a useful and beneficial manner to site owners. An example of a well designed harvest and reuse system that serves multiple purposes can be found in Thailand at the Chulalongkorn University