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Assessing the effectiveness of drywells as tools for stormwater management and aquifer recharge and their groundwater contamination potential
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Assessing the effectiveness of drywells as tools for stormwater management and aquifer recharge and their groundwater contamination potential
Science Direct | May 24, 2016...
Summary
Drywells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas where drainage and diversion of...
Drywells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas where drainage and diversion of storm flows is problematic. Historically, drywells have predominantly been used as a form of stormwater management in locations that receive high volumes of precipitation; however the use of drywells is increasingly being evaluated as a method to supplement groundwater recharge, especially in areas facing severe drought.

Studies have shown that drywells can be an effective means to increase recharge to aquifers; however, the potential for groundwater contamination caused by polluted stormwater runoff bypassing transport through surface soil and near surface sediment has prevented more widespread use of drywells as a recharge mechanism. Numerous studies have shown that groundwater and drinking water contamination from drywells can be avoided if drywells are used in appropriate locations and properly maintained.

The effectiveness of drywells for aquifer recharge depends on the hydrogeologic setting and land use surrounding a site, as well as influent stormwater quantity and quality. These parameters may be informed for a specific drywell site through geologic and hydrologic characterization and adequate monitoring of stormwater and groundwater quality.

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Clean Water, Clean Beaches Water Quality Funding Measure*

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Clean Water, Clean Beaches Water Quality Funding Measure*
Los Angeles County Department of Public Works, Los Angeles County Flood Control District | September 21, 2012...
Summary
The Problem: Stormwater and runoff rushes down the street, picking up trash and toxic pollutants. On a rainy day, over 10 billion gallons...

The Problem: Stormwater and runoff rushes down the street, picking up trash and toxic pollutants. On a rainy day, over 10 billion gallons of contaminated stormwater flows directly — untreated — into rivers, creeks, lakes and our bay and coastal waters. Polluted stormwater and urban runoff include toxins and pathogens that can affect our health, drinking water supplies, and the health of marine life. Contaminants include: Industrial solvents, paints and chemicals; heavy metals like lead, mercury, chromium and arsenic; infection-causing bacteria; pesticides and fertilizers; and trash like plastics, cigarette butts, candy wrappers and syringes.

*The proposed solution, a parcel tax to fund stormwater remediation and capture projects, failed before the Los Angeles County Board of Supervisors in 2013.

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Estimating Monetized Benefits of Groundwater Recharge from Stormwater Retention Practices
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Estimating Monetized Benefits of Groundwater Recharge from Stormwater Retention Practices
U.S. Environmental Protection Agency (EPA) | February 4, 2016...
Summary
Stormwater impacts from development have been documented extensively in peer-reviewed literature and summarized in the National Research Council’s report titled Urban Stormwater Management...
Stormwater impacts from development have been documented extensively in peer-reviewed literature and summarized in the National Research Council’s report titled Urban Stormwater Management in the United States (National Research Council, 2009). To address these impacts, the U.S. Environmental Protection Agency (EPA) Office of Water (OW) evaluated several potential scenarios for managing stormwater from new development and redevelopment using small stormwater retention practices. The objective of these practices is to reduce runoff volume to simulate pre-development hydrology and protect water quality. These practices are often designed to infiltrate the retained water, which can provide groundwater recharge to help maintain predevelopment groundwater levels. For the purposes of this study, infiltration was assumed, whereas in practice capture-and-use or other methods also may be applied.

The purpose of the study is to inform valuation of groundwater recharge from stormwater retention in areas projected for new development and redevelopment. Retention practices can prevent the loss of natural recharge that may occur on a developed site without these practices. This study examined a simplified methodology for estimating recharge volume and used observed prices of water for monetary valuation.

Groundwater recharge is just one benefit within the larger context of the costs and benefits of stormwater retention practices. The full range of potential benefits were not addressed in this study, but the full suite of benefits should be considered when comparing to an estimated cost of implementation. Costs of implementing retention practices in areas of new and redevelopment also were not addressed in this study.

The estimates represent the groundwater recharge volume and value that would result if stormwater retention practices were implemented in areas within the contiguous U.S. not currently requiring stormwater retention. The stormwater retention practices were assumed to capture a specified depth of runoff, in the range of 0.5 to 2 inches (i.e. not large storm attenuation) with a goal of reducing runoff volumes to levels similar to those for pre-developed landscape conditions. This approach is commonly referred to as “green infrastructure” for stormwater management or low impact development (LID). While small storm retention that approximates predevelopment runoff could also be achieved with cisterns in those areas where infiltration is not desired or is not feasible, the option of cistern capture was not evaluated in this study. The timeframe selected for the purpose of the predictive study was the 20-year period of 2021 through 2040.

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LA Sustainable Water Project: Los Angeles City-Wide Overview

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LA Sustainable Water Project: Los Angeles City-Wide Overview
UCLA: Sustainable LA Grand Challenge | February 1, 2018...
Summary
This report assesses the potential to improve water quality standards while integrating complementary One Water Management practices that can increase potential local water...
This report assesses the potential to improve water quality standards while integrating complementary One Water Management practices that can increase potential local water supplies for the City of Los Angeles (the City). This final report summarizes the current practices and future opportunities at the City-owned Water Reclamation Plants and underlying groundwater basins and highlights the importance of considering all aspects of integrated water management even when dealing with water quality or supply-focused projects.

Implementing watershed-scale best management practice programs to meet stormwater permit requirements will significantly improve water quality in all watersheds. However, additional mechanisms such as increasing Low Impact Development implementation and comprehensive source tracking and source control mechanisms will be required to potentially eliminate water quality exceedances. There are multiple efforts occurring in the City and the region to increase the recharge of recycled water into the ground and the volumes of remediated groundwater extracted.

This research further assessed the impacts of potential water supply portfolios, with greater volumes of locally-supplied water, on GHG emissions and energy needs of supplying LA’s water. Conservation will be another powerful tool to decrease our dependence on imported water. This research demonstrates the complex interrelationships between all aspects of urban water management, including, for example, stormwater management and local water supply.

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LA Sustainable Water Project: Los Angeles River Watershed

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LA Sustainable Water Project: Los Angeles River Watershed
UCLA: Sustainable LA Grand Challenge | September 1, 2017...
Summary
The LA Sustainable Water Project: Los Angeles River Watershed report explores the potential to improve water quality standards while integrating complementary One Water...
The LA Sustainable Water Project: Los Angeles River Watershed report explores the potential to improve water quality standards while integrating complementary One Water Management practices that can increase potential local water supplies for the City of Los Angeles (the City) in the highly urbanized Los Angeles River (LAR) watershed.To assess the integrated water landscape in this watershed, the report also looks at current practices and future opportunities at the Donald C Tillman, LA Glendale, and Burbank Water Reclamation Plants (WRPs) and in the underlying Upper LA River Area (ULARA) adjudicated groundwater basins. Implementing watershed-scale best management practice programs to meet stormwater permit requirements will significantly improve water quality. However, additional mechanisms such as increasing Low Impact Development implementation and comprehensive source tracking and source control mechanisms will be required to potentially eliminate water quality exceedances. The 3 WRPs in the watershed currently discharge more than 30 million gallons per day of treated wastewater into the River; an increased focus on increasing local water supply could lead to a reduction in these discharges.

The combination of increased stormwater capture and increased use of recycled water in the LAR watershed could lead to lower flows in the LAR and impact habitat and recreational uses; further study is needed to characterize potential impacts and identify optimal flows for the future of the LAR. The City is leading efforts in ULARA to increase the recharge of recycled water into theground by 30,000 acre feet per year and increase the volumes of remediated groundwater extracted by around 120,000 acre feet per year. This research demonstrates the complex interrelationships between all aspects of urban water management, including stormwater management and local water supply.

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LADWP Stormwater Capture Master Plan
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LADWP Stormwater Capture Master Plan
Los Angeles Department of Water and Power (LADWP) | October 5, 2015...
Summary
To ensure a safe and reliable water supply for future generations of Angelenos, one of the City’s key strategies is to increase the...
To ensure a safe and reliable water supply for future generations of Angelenos, one of the City’s key strategies is to increase the local water supply and decrease the need to purchase imported water. However, in large part due to urbanization, the majority of precipitation that falls onto the City flows into storm drains and out to the ocean. In light of these conditions, stormwater is an increasingly viable supply.

Capturing and using stormwater on-site can offset potable water demand. Capturing and infiltrating stormwater into subsurface groundwater aquifers increases local groundwater reserves. Both infiltration and capture for direct use enhance the reliability of the City’s water supply. Projects to capture and conserve stormwater runoff comprise an important component of the City’s water supply portfolio. The City is a part of a complex multi-jurisdictional region. As such, implementing effective and comprehensive local stormwater capture projects involves a collaborative effort between several agencies including LADWP, the Los Angeles County Flood Control District (LACFCD), the Los Angeles Bureau of Sanitation (LASAN), the Los Angeles Bureau of Street Services (LABSS), the Los Angeles Bureau of Engineering (LABOE), and the US Army Corps of Engineers (USACE).

Additionally, LADWP partners with many community-based organizations to leverage their relationships with the residents of the City. Working together on projects that have multi-benefits for multiple agencies allows for the opportunity to cost-share and reduces the financial burden.

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Los Angeles Basin Study
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Los Angeles Basin Study
U.S. Bureau of Reclamation (USBR) | November 1, 2016...
Summary
Changing demographics, climate change, and competing interests for available water supplies all present long-term risks to the stability and reliability of the region’s...
Changing demographics, climate change, and competing interests for available water supplies all present long-term risks to the stability and reliability of the region’s imported water. The region recognizes that today’s challenges require an integrated water resources management approach.

For decades, this region has operated and maintained one of the most effective flood control systems in the world that protects millions of people from the impacts of flooding in the region. This system sends much of the stormwater runoff into the ocean, water that historically recharged local groundwater basins, making this region even more dependent on imported water supplies. As regulatory pressure to clean up polluted stormwater runoff continues and imported water resources diminish, this local source of water supply is becoming more and more attractive (GLAC IRWMP 2014).

Many of the region’s water management agencies have studied and planned for increasing use of local recycled and graywater supplies, ocean and brackish desalination, developing more groundwater, and implementing improved water conservation initiatives to extend existing supplies. Additionally, social trends and concerns also drive the emphasis on the use of local water supplies.

However, the one major local resource that has not been studied in-depth is stormwater and its opportunities to optimize the reliability of local supplies.

To enhance the capabilities of the existing stormwater conservation infrastructure within the Los Angeles Basin, the LACFCD began to investigate long-term projected needs and future climate conditions within the region. Given that local groundwater plays such a vital role in the region’s water supply portfolio, detailed scientific, engineering, and economic analyses were conducted to identify strategies for enhancing stormwater capture for groundwater recharge.

The LA Basin Study examined the region’s water supplies and demand, and impacts from projected population growth and changing climate in the watersheds of the Los Angeles region. The objectives of the study were to:

• Use state-of-the-art climate change analysis to develop projections of future water supply and demands in the Basin.
• Analyze how the Basin’s existing water infrastructure and its operations will perform in the face of changing water realities.
• Develop and highlight opportunities to adapt to current and future water demands.
• Conduct a trade-off analysis of identified opportunities.

Concepts ranged from enhancing the existing stormwater capture system and modifying existing facilities (including those capturing runoff for groundwater recharge), to developing new structural and nonstructural concepts that could help resolve future water supply and flood risk issues.
This Summary Report presents highlights of the critical tasks associated with this Basin Study and the results and findings produced throughout this collaborative study effort.

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Los Angeles Sustainable Water Project: Ballona Creek Watershed

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Los Angeles Sustainable Water Project: Ballona Creek Watershed
UCLA: Sustainable LA Grand Challenge | November 1, 2015...
Summary
Implementing integrated water management systems (IWM) that incorporate all components of the urban water cycle, including imported water, local groundwater, captured stormwater, greywater, and treated...
Implementing integrated water management systems (IWM) that incorporate all components of the urban water cycle, including imported water, local groundwater, captured stormwater, greywater, and treated wastewater is crucial to creating a sustainable water supply for the city of Los Angeles (City). The City has researched, written, and initiated implementation of recommendations from many reports critical to creating an IWM plan for the City as well as to defining the current capacity of the system. While work on this issue has been ongoing for many years, the extreme drought currently impacting water supplies throughout California has created a new urgency to increase the City’s ability to provide a secure water supply through local sources. In April 2015, Governor Brown directed the first-ever statewide mandatory cut of 25% in urban water use due to the continuing drought conditions.

In addition to statewide efforts, many policies and plans have been created on a local level within the City that address urban water management, integrated resources planning, stormwater capture, and groundwater management. The Los Angeles Mayor’s Office recently set strong goals to increase the sustainability of the City’s water supply over the next several years. The goals included completing a comprehensive sustainability plan containing objectives for water supply and demand in the City, which was released in April 2015 (Sustainable City pLAn). In an emergency drought directive released in October 2014, the Mayor identified additional accelerated water goals including reducing per capita potable water use by 20% by 2017 (from 2014 base-line of 130 gallons per capita per day (GPCD) to 104 GPCD), reducing the City’s reliance on MWD water by 50% by 2025, and converting 85% of public golf course acreage to recycled water by 2017.

Through building upon regional research and reports that have been generated on potential components of the local water supply portfolio (e.g., groundwater, recycled water, and stormwater), as well as gathering and analyzing current data on flows of water and wastewater throughout the City systems and environment, this project further identifies and refines opportunities to implement integrated water management throughout the City. As water quality regulation in the Los Angeles area currently drives much of the current water management practices, we examined greater water self-reliance through this lens. Therefore, the City has been divided by watershed to assess Total Maximum Daily Load (TMDL) compliance alongside integrated water management opportunities and challenges that exist and must be addressed in order to meet water quality compliance requirements and maximize local water supply. This first report focuses on the Ballona Creek Watershed and the Hyperion Service Area; following reports will focus on the Dominguez Channel and Los Angeles River watersheds.

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Modeling Cost, Energy, and Total Organic Carbon Trade-Offs for Stormwater Spreading Basin Systems Receiving Recycled Water Produced Using Membrane-Based, Ozone-Based, and Hybrid Advanced Treatment Trains

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Modeling Cost, Energy, and Total Organic Carbon Trade-Offs for Stormwater Spreading Basin Systems Receiving Recycled Water Produced Using Membrane-Based, Ozone-Based, and Hybrid Advanced Treatment Trains
American Chemical Society (ACS) | January 31, 2019...
Summary
To address water scarcity, cities are pursuing options for augmenting groundwater recharge with recycled water. Ozone-based treatment trains comprising ozone and biologically activated...
To address water scarcity, cities are pursuing options for augmenting groundwater recharge with recycled water. Ozone-based treatment trains comprising ozone and biologically activated carbon potentially offer cost-effective alternatives to membrane-based treatment, the standard process for potable reuse in numerous countries. However, regulations in multiple states effectively limit the extent to which ozone-based treatment alone can produce recycled water for groundwater recharge. To investigate the trade-offs between treatment costs and regulatory constraints, this study presents methods for modeling and optimizing designs for (1) producing recycled water using membrane-based treatment, ozone-based treatment, and hybrid treatment trains comprising ozone-based treatment with a membrane sidestream, and (2) delivering that water to stormwater spreading basins. We present a case study of Los Angeles, CA, to demonstrate the model’s application under realistic conditions, including regulations that limit spreading recycled water based on its concentration of total organic carbon and the extent of dilution. While the membrane-based treatment train exhibits economies of scale, we demonstrate how regulatory constraints create a diseconomies of scale effect for hybrid treatment systems because larger scales necessitate a higher proportion of recycled water undergo membrane treatment. Nevertheless, relative to membrane-based treatment, we identify opportunities for ozone-based or hybrid treatment trains to reduce treatment costs and energy use by up to 62% and 59%, respectively, for systems with up to 1 m³/s (23 million gallons per day) mean water recycling rate, potentially lowering the barrier for decentralized water recycling systems. This modeling approach could inform planning and policy regarding recycled water projects for groundwater recharge through spreading basins and, with additional modification, other potable reuse applications.

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Moving Toward a Multi-Benefit Approach for Water Management

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Moving Toward a Multi-Benefit Approach for Water Management
Pacific Institute | April 11, 2019...
Summary
There is broad recognition that adapting to climate change, coupled with the need to address aging infrastructure, population growth, and degraded ecosystems, will require rethinking programs and...
There is broad recognition that adapting to climate change, coupled with the need to address aging infrastructure, population growth, and degraded ecosystems, will require rethinking programs and policies and investing in our natural and built water systems. There are a variety of strategies for addressing water challenges, from watershed restoration and efficiency improvements to vegetated swales and green roofs. Because water is deeply linked with economic, environmental, and community wellbeing, many of these strategies can also provide other benefits, such as reducing energy use and greenhouse gas emissions, providing wildlife habitat, and enhancing community livability.

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