Geosyntec will make a significant technical contribution at the California Stormwater Quality Association (CASQA) Annual Conference at the Riverside Convention Center in Riverside, California on October 15-17, 2018.

Geosyntec-led contributions include presentations and a panel discussion. A number of the presentations will be given in partnership with clients.

The CASQA Annual Conference offers an opportunity to interact with professionals in the stormwater field. Each year the conference draws members of the stormwater community including local, state, and federal decision makers, stormwater program coordinators, contractors, consultants, engineers, lawyers, scientists, and planners. Over 1,000 attendees and 60 exhibitors are expected for three days of training and discussions on the future of our stormwater programs.

The California Stormwater Quality Association (CASQA) is a professional member association dedicated to the advancement of stormwater quality management through collaboration, education, implementation guidance, regulatory review, and scientific assessment. CASQA has been a leader since 1989 when the field of stormwater management was in its infancy. CASQA's membership is comprised of a diverse range of stormwater quality management organizations and individuals, including cities, counties, special districts, industries, and consulting firms throughout the state. A large part of their mission is to assist California stormwater permittees in developing, implementing, and maintaining effective stormwater quality management programs, and to draw upon the collective experiences of its individual members.

Geosyntec Contributions

Panel Presentation

Title: OC Stormwater Tools: A Collaborative, Open-Source Web-App to Support the Lifecycle of Watershed Plan Implementation
Presenters: Cindy Rivers (OCPW) and Aaron Poresky (Geosyntec)
All Authors: Cindy Rivers (OCPW), Grant Sharp (OCPW), Aaron Poresky (Geosyntec), John Burns (Sitka Technology Group), Avery Blackwell (Geosyntec)
Session: Innovation in Data Track / Innovation Using Open Source Technology and Public Data Sharing
Time: 3:45 - 5:25 p.m. on Tuesday, October 16th
Abstract:
The South Orange County Watershed Management Area (WMA) is initiating implementation of its Water Quality Improvement Plan (WQIP), which describes priorities, goals, strategies, monitoring activities, and adaptive management approaches that will be implemented over the next 30 to 40 years.

To support key elements of the WQIP lifecycle, the South OC WMA is developing an open-source web application – the OC Stormwater Tools. The long-term purposes of the application include: (1) building and maintaining consistent BMP asset datasets, (2) supporting rapid BMP condition assessment and maintenance tracking, (3) supporting monitoring, assessment and adaptive management via integrated performance modeling and streamlined reporting, and (4) supporting new project development and funding, including integrated regional water management (IRWM) projects.

The first phase of this effort was initiated in December 2017 and will go into use in July 2018 to help MS4 Permittees improve asset inventories, conduct inspections, and track maintenance activities for BMPs ranging from trash capture screens to major regional IRWM projects. Users will include Permittee stormwater program managers, technical staff, field personnel, and maintenance contractors. Development of the application was supported by extensive user testing and individual Permittee interviews intended to detail existing workflows and build upon current datasets. Based on this input, custom workflows were integrated into the application to improve the simplicity of the user experience while improving the quality and completeness of collected data. The application supports approximately 15 typical stormwater BMP types and allows BMP types, observation types, and attributes to be added and configured by an administrative user. It also supports trash capture devices and "On Land Visual Trash Assessment."

The application is open source (GNU Affero General Public License). This means it can be freely redistributed and/or modified under the terms of the open source license. The Stormwater Tools application is derived from the Tahoe Regional Planning Agency's Lake Tahoe Info Stormwater Tools, with substantial additions and enhancements contributed to the source code as part of this project.

This presentation will focus on three key elements:

• The functionality of the OC Stormwater Tools application and the vision for how this will support WQIP implementation in South OC.
• The collaborative tool development process, including how user input was collected and used to define and prioritize application functionality.
• The factors that led Orange County to build this application in the open source domain, and how this creates opportunities for broader community engagement around this application.

Oral Presentations

Title: Stormwater Public-Private Partnerships (P3s) as Potential Solutions for Meeting Stormwater Needs: A Summary of Perspectives from the 2018 National P3 Water Summit
Presenter and Author: Ken Susilo
Session: Dollars and Sense Track / Alternative Procurement and Delivery Methods
Time: 3:45 - 4:15 p.m. on Tuesday, October 16th
Abstract:
Interest in Public-Private Partnerships (or P3s) and Performance Based Contracting (PBC) for implementation of water quality and water resources projects has increased significantly of late in California. There remain a significant number of questions (and misconceptions), regarding the types of P3s, applicability for various agencies, implementation requirements (administrative, financial, and legal), risk transfer potential, benefits and drawbacks. Key to understanding issues raised by these questions is the establishment of a basic common language. The 2018 national P3 Water Summit included a focused series of roundtable and panel discussions on stormwater P3s. Specific attention was given to California-specific perceptions of P3s, MS4 (and TMDL) and Industrial General Permit requirements, financial considerations, water resources benefits, and the administrative challenges of implementation (and generally, of stormwater infrastructure elements). Summit panelists from around the country provided insightful examples of successful programs and lessons learned, critically helpful to any agency contemplating a P3-type framework as an alternative approach to implementation (particularly multi-benefit implementation) and project delivery.

Title: Innovations in Stormwater Capture Incentivization: LADWP's Plan for an Industrial Stormwater Rebate Program
Presenters: Art Castro (Los Angeles Department of Water and Power); Brandon Steets (Geosyntec)
Session: Industrial Track / Alternative Compliance and Incentives
Time: 1:20 - 1:50 p.m. on Wednesday, October 17th
Geosyntec Authors: Adam Questad, Brandon Steets
Abstract:
The Los Angeles Department of Water and Power (LADWP) recently developed a strategic plan to encourage and incentivize industrial stormwater dischargers through a rebate program to implement infiltration or capture/re-use projects in order to promote achievement of LADWP's stormwater capture and water supply goals. LADWP worked with Ortega Strategies Group, Geosyntec Consultants, and Waterkeeper to outline the framework for such a plan and program and to engage the Non-governmental organizations (NGO) and the industrial community while doing so. Key components to the development of this plan included outlining and implementing a communications and outreach strategy, evaluating the opportunities and constraints of the rebate program, identifying potential industrial stormwater dischargers that may be interested in the program, quantification of the potential water supply augmentation benefit available through the program, cost and rebate implication comparisons of hypothetical discharger site scenarios, stakeholder and regulatory outreach public meetings, and final synthesis of the gathered information and data into a cohesive strategic plan outlining how the plan will be implemented and how interested parties will apply.

The focus of this presentation will be on the technical evaluations performed including:

• an evaluation of the quantity of industrial stormwater sites (and their acreage) that may be eligible for the proposed rebate based on geophysical land categories identified in the LADWP stormwater capture master plan;
• a SMARTS data analysis to identify pollutants of concern that may exceed groundwater quality objectives even when accounting for pretreatment; and
• estimation of the water supply benefit available through the potential rebate program; and the cost comparison of hypothetical structural BMP planning options (e..g, infiltration basins, active and natural flow through treatment BMPs, treatment and injection drywells, capture/re-use, and offsite regional BMP contribution).

In addition to the above, additional constraints will also be identified along with potential mitigation strategies including provisions for verification and monitoring and groundwater and surface water protection. We believe that this presentation will be relevant and engaging to the industrial stormwater community as it presents an opportunity for those within LADWP's jurisdiction that may be in the middle of or beginning Level 2 Exceedance Response Action planning under the statewide industrial general permit and because many of the technical evaluations performed are relevant to other municipalities or water purveyors that may be considering means to promote alternative water sources.  This presentation ties directly into the conferences theme as LADWP is trying to capture every drop of water from "summit to sea" and provide innovative methods for encouraging infiltration and water reuse. 

LADWP staff will also be available to provide an overview of the program, a schedule for possible implementation, and answer technical and policy questions.

Title: Development of New Statewide Guidance on Drywell Siting, Design, and Implementation
Presenters: Matthew Freese (SWRCB) and Ken Susilo (Geosyntec)
Session: Prioritize and Clarify Regulations Track / Prioritize Regulations to Improve MS4 Water Management Outcomes
Time: 10:20 - 10:50 a.m. on Tuesday, October 16th
Geosyntec Authors: Adam Questad, Brandon Steets, Ken Susilo, Aaron Poresky
Abstract:
The State Water Resources Control Board (SWRCB) is working with Geosyntec Consultants to develop statewide guidance for the siting, design, and implementation of drywells. Municipalities, developers, and commercial/industrial operators are increasingly turning to drywells as a cost-effective stormwater best management practice in order to protect downstream surface water quality, while also providing water supply benefit. In addition, drywells are a convenient solution when space is limited due to their small footprint and because they provide opportunities to infiltrate in deeper permeable soil layers when the surface infiltration may be limited. While these benefits are evident clear statewide guidance on how to safely implement drywells in order to protect groundwater quality and public health is lacking. The SWRCB and Geosyntec, along with a technical advisory committee (TAC) including industry, municipality, and institutional stormwater and groundwater practitioners, are beginning a study to evaluate what existing guidance exists, synthesize available water quality data, and identify modeling or data needs to understand how to safely implement drywells throughout California. 

The purpose of this presentation will be to provide an overview of the project, including the findings of our initial research and other progress, as well as a summary of work under development and potential future planning efforts. The framework of this guidance is still being developed but may include:  groundwater quality protection (including applicable standards and points of compliance), spill containment, clogging reduction, pretreatment selection (based on the preceding three factors), geotechnical risk avoidance, groundwater mounding characterization and impacts, infiltration rate estimation and sizing, existing soil or groundwater contamination, permitting, construction, monitoring and other aspects. According to the SWRCB and TAC priorities, contaminate fate and transport modeling, hydrogeology and geochemical condition evaluations to understand plume migration, and pollutant vadose zone modeling may be reviewed or performed to inform the final guidance. 

The audience will be invited to participate through a Q&A session to clarify how this guidance may relate to their past, ongoing, or future drywell projects. This presentation is directly related to the conference's theme of "Summit to Sea" as it is outlining guidance for a cost-effective tool capable of capturing and infiltrating stormwater runoff from upland watersheds, thus reducing pollutant discharges to downstream receiving water bodies, while also replenishing groundwater aquifers.

Title: Case Studies Implementing the CASQA IGP Non-Industrial Demonstration Manual (and Expanding Beyond Atmospheric Deposition)
Presenter: Brandon Steets
Session: Industrial Track / Compliance Strategies
Time: 9:10 - 9:40 a.m. on Wednesday, October 17th
Geosyntec Authors: Adam Questad, Maia Colyar, Jared Ervin, Brandon Steets
Abstract:
The CASQA industrial General Permit (IGP) subcommittee, in partnership with Geosyntec Consultants, developed a draft IGP Non-Industrial Demonstration Manual outlining steps for IGP dischargers to evaluate whether their numeric action level (NAL) exceedances are likely attributed to atmospheric deposition sources.  The manual also outlines steps for developing a sampling plan as part of the Level 2 Exceedance Response Action (ERA) Action Plan to demonstrate that these sources are the sole cause of NAL exceedances. This presentation will briefly summarize the flow chart in this manual outlining the evaluation steps along with a brief overview of sampling guidance.  The majority of this presentation will then discuss a real-world case study where the steps in the manual, or similar steps, have been implemented.  In addition, this presentation will provide an overview of other non-industrial and background sources such as parking lots, roadways, buildings, soil, etc., and tips for applying the concepts from the manual to demonstrate whether these sources may be causing NAL exceedances.

The case study will include Boeing's Santa Susana Field Laboratory (SSFL) located in eastern Ventura County. Stormwater discharges are regulated through an individual industrial NPDES permit that includes Water Quality Based Effluent Limits (WQBELs) for multiple pollutants. Despite the implementation of multiple stormwater treatment controls, monitoring results at some outfalls have occasionally exceeded WQBELs. In response, a study was developed to evaluate the contribution of non-industrial pollutant sources to stormwater runoff including solids deposited on paved parking lots and roads, sediments near treated wood utility poles, aerial deposition, and natural background soils.  The hypothesis-driven study will be outlined, including an explanation of how multiple lines of evidence were used to identify non-industrial sources such as dioxin congener fingerprinting and lead isotope analysis.  In addition, off-site sampling of stormwater, pavement solids, and soils near utility poles was also conducted to understand typical dioxins and lead concentrations in stormwater from these sources. The results of this case study, which are applicable to other urban and industrial areas, will be presented and include pavement solids and utility pole soils as potential sources of dioxins exceedances along with atmospheric deposition and pavement solids in high traffic areas as the potential sources of lead exceedances.

We believe that the industrial and municipal CASQA audience will be very interested in this presentation as many permittees are considering background and non-industrial source demonstrations as part of the IGP ERA process.  Not only will this presentation provide guidance on how to develop a robust sampling plan, but it will also present preliminary results for dioxins and lead indicating some potential non-industrial sources, which may be useful if permittees are dealing with high levels of these parameters at their facilities. In addition, this abstract is in line with the conference's theme since identifying what sources of pollutants of concern need to be addressed as water travels from "summit to sea" is an important component of protecting our downstream receiving waters.

Title: What's in my MS4 Discharge? A New Procedure for Determining Groundwater-Based Flows in Dry Weather
Presenters: Joanna Wisniewska (San Diego County), Stacey Isaac (Geosyntec)
Session: Municipal Track / Dry Weather Flows
Time: 10:55 - 11:25 a.m. on Tuesday, October 16th
Geosyntec Authors: Jared Ervin, Stacey Isaac, Brandon Steets
Abstract:
Dry weather discharges into MS4s can occur due to a variety of sources and may contribute or mobilize pollutants such as bacteria and nutrients to receiving waters.  For example, these discharges may be attributed to sewage (e.g., overflows, sewer exfiltration, illicit connections), recycled water (e.g., distribution system leaks, irrigation), potable water (e.g., leaks, irrigation, wash water, pool draining), and/or natural waters (e.g., groundwater, springs).

The MS4 Permit for the San Diego Region requires permittees to eliminate most dry weather MS4 discharges. The County of San Diego (County) implements an illicit discharge detection and elimination (IDDE) program to identify and abate anthropogenic discharges including sewage, recycled (reclaimed) water, and potable water. However, naturally occurring groundwater seepage is an allowable non-stormwater discharge. Thus, efficient and conclusive differentiation of MS4 discharge water sources is critical to the County and other MS4 agencies for permit compliance demonstration.

The County wished to develop a methodology for identifying contributions to dry weather MS4 discharges that are caused by groundwater as opposed to the anthropogenic sources listed above. A literature review was first conducted on available methods for distinguishing such flows. Groundwater, potable water, and recycled water data were then compiled from various local sources and analyzed to identify analytes and associated concentration ranges that reflect each water source. Water quality data and watershed boundaries, groundwater basins, and water district service areas were analyzed using GIS to identify analytes that were more useful in certain areas within the County.

As a result, a Groundwater Detection Manual was developed describing sampling and analysis procedures for the identification of groundwater in MS4 discharges in the County. This Manual presents an approach for distinguishing groundwater discharges from other anthropogenic sources, using a tiered approach for sampling in which low-cost conventional methods are first used. These methods involve outfall sampling and comparing the results for basic analytes (i.e., fluoride, nitrate, boron, total residual chlorine, surfactants, and TDS) with expected ranges for the potential water sources. If the results for the low-cost conventional methods are not conclusive in determining the source of the discharge and further evidence is required, slightly more expensive analytes are considered (i.e., trihalomethanes), followed by more advanced ion analyses and then finally isotope analyses. This tiered approach allows for a cost-effective means of executing the Manual's procedures. Also, a field "cheat sheet" was created to concisely guide staff in the selection of sampling analytes and concentration ranges for each water source.

The County now has a robust, scientifically-based, and transparent methodology for determining the source of non-stormwater discharges across hundreds of MS4 outfalls, for demonstration of compliance with MS4 permit discharge prohibitions and other requirements. This approach may be reproduced for other agencies, using expected concentration ranges based on area-specific data.

This presentation will summarize the approach outlined in the Manual, including how the tiered approach allows for net cost savings. The interactive GIS tool to aid in execution of the Manual will also be presented.

The audience will be invited to participate through a Q&A session to discuss the utility of the Manual for other example applications. This presentation is directly related to the conference's theme as it outlines new available guidance for efficient and cost-effective MS4 discharge source determination, which is a highly effective means of protecting downstream receiving waters.

This presentation is intended to be second in a three-part series. Linked with:
Data to Doorsteps, Norris, Scott
Isotope Isolation, Messina, Alex

Title: Santa Barbara Beaches MST Study - Case Study on MST at High Use Beaches
Presenter: Brandon Steets
Session: Innovation in Data Track / Innovation in BMP Design and Effectiveness Tracking
Time: 2:30 - 3:00 p.m. on Wednesday, October 17th
Geosyntec Authors: Brandon Steets, Avery Blackwell, Jared Ervin
Abstract:
Elevated concentrations of fecal indicator bacteria (FIB) in receiving waters throughout California raise serious concerns for the protection of human health, and public agencies have spent millions of dollars implementing structural BMPs to address this problem. With the future price tag in the billions of dollars for the installation and maintenance of adequate structural BMPs to bring public agencies into compliance with FIB TMDLs, Microbial Source Tracking (MST) offers a cost-effective option to identify the highest priority bacteria sources (i.e., contributions from humans) and implement targeted source control and abatement BMPs.

The California Microbial Source Identification Manual is recognized by California regulators and USEPA as the leading guidance on MST. The Manual, co-authored by UCSB's Dr. Trish Holden with contribution from Geosyntec's Dr. Jared Ervin, is the result of the Source Identification Protocol Project (SIPP). For the SIPP, Dr. Ervin led one of four field demonstrations to test DNA markers in an urban watershed, resulting in a case study demonstrating successful identification and remedy of anthropogenic sources. During these studies, human markers were detected at three other Santa Barbara beaches, which Geosyntec and UCSB researchers used as the basis for a successful Clean Beaches Initiative research grant application. The objective of this project is to determine sources of human and/or other anthropogenic wastes at these beaches and prescribe targeted abatement remedies.

Geosyntec and UCSB, with feedback from local stakeholders, developed and implemented a comprehensive MST Monitoring Plan and Quality Assurance Project Plan to: (a) identify sources of human and non-human waste to Leadbetter Beach, East Beach at Sycamore Creek, and Goleta Beach and Slough, and (b) support local agencies in identification of management actions for improving beach water quality. The Plan was designed based on a hypothesis-driven and tiered investigation approaches. The Plan includes flexible milestones and offramps such that identified sources can be addressed immediately rather than waiting until study completion.

This presentation will discuss the implementation, findings, and conclusions stemming from the past three years of executing the MST Monitoring Plan, as well as provide practical connections and take-away guidance to assist MS4 managers throughout California. Nearly a dozen hypotheses (e.g., background sources, MS4 and sewer contributions, leaking or failing septic, WWTP effluent) were investigated (and conclusively eliminated) to identify sources of human bacteria persistently detected at these important local beaches. Through field investigations, numerous beach, slough, creek, storm drain outfalls, sewers, and boat areas were evaluated for human fecal contamination and other non-human sources. Where human waste markers were detected, they were tracked to their points of origin in combination with analytical and field investigation tools (e.g., CCTV, visual observations, sewer dye testing, groundwater sampling, etc.). Recent results directed investigations towards hypothesis testing of bather shedding and open defecation (e.g., by homeless persons) as potential sources. This State funded collaborative effort between Geosyntec and UCSB demonstrates a state of the science MST practical investigation to achieve meaningful public health benefits and to support the compliance efforts of permitted public agencies, which include both the MS4 agencies and local sanitation districts

The audience will be invited to participate through a Q&A session to discuss guidance for developing and implementing a hypothesis driven MST investigation specific to their watershed conditions. This presentation is directly related to the conference's theme as it describes how MST has been utilized to "connects the drops" between elevated FIB concentrations and the identification and abatement of human bacteria sources.

Title: Connecting Various Watershed Planning Requirement Drops Using the LPR Model
Presenters: Cathleen Garnand (Santa Barbara County) and Avery Blackwell (Geosyntec)
Session: Municipal Track / Implementation
Time: 2:45 - 3:15 p.m. on Tuesday, October 16th
Geosyntec Authors: Avery Blackwell, Stacey Isaac, Brandon Steets
Abstract:
Municipal agencies face a growing number of MS4 permit and watershed planning and compliance obligations. Many of these obligations require the quantification of expected runoff volumes and pollutant loads, as well as the runoff volume and pollutant load reductions estimated for planned or implemented BMPs. For example, the 2013 California Phase II General MS4 Permit (MS4 Permit) specifically requires a Program Effectiveness Assessment and Improvement Plan (PEAIP) to include "quantification of pollutant loads and pollutant load reductions achieved by the program as a whole" (Section E.14.a.ii.a.6). The MS4 Permit Draft Attachment G includes a TMDL implementation requirement to provide "a quantifiable numeric analysis that uses published BMP pollutant removal estimates, performance estimates, modeling, best professional judgment, and/or other available tools to demonstrate that the BMP selected for implementation achieved the MS4's wasteload allocation". The California Storm Water Resource Plan Guidelines require "a metrics-based and integrated evaluation and analysis of multiple benefits". The Water Code Section 13383 Orders to Phase II MS4 Permittees requires a plan demonstrating that controls will achieve Full Capture System Equivalency of the trash generated from all Priority Land Uses (or equivalent alternative land uses).

In 2015, the County of Santa Barbara, and the Cities of Buellton, Solvang, Goleta, and Carpinteria (jurisdictions), along with Geosyntec Consultants (Geosyntec), developed a baseline pollutant load quantification, catchment prioritization, and BMP reduction model (LPR Model) to address these requirements. The LPR Model is accessible from an easy to use Excel interface and consists of five main components: 1) calculating the MS4 Permit Area and watershed baseline wet weather annual average pollutant load/runoff volume; 2) prioritizing catchments for program improvements; 3) tracking BMP implementation details (e.g., type of BMP implemented, catchment(s) implemented on, applicable land uses, etc.); 4) estimating the BMP pollutant load/runoff volume reductions; and 5) summarizing and formatting all results for easy reporting.

In this presentation we will describe recent enhancements that expand the capabilities to the LPR Model, including analysis and incorporation of new local land use monitoring data, determination of BMP capture estimates based on BMP design and local rainfall/runoff hydrology, ability to adjust runoff volumes based on the hydrologic connectivity of outfalls, and incorporation of maintenance condition into BMP performance estimates. Additionally, a module is currently under development to evaluate trash capture scenarios for both Track 1 and 2 and to demonstrate ongoing progress towards 100 percent compliance with the Trash Provision.

Then we will provide brief case studies of how the LPR Model is being implemented by MS4 permittees across the State to successfully and efficiently fulfill various but connected watershed planning and compliance obligations directly applicable to the audience, including 1) the quantification of multiple benefits (pollutant load reductions, groundwater recharge, and flood management benefits) for dozens of projects included in SWRPs; 2) tracking, quantification, and prioritization of public and private stormwater retrofit projects to meet MS4 Permit PEAIP requirements, 3) forecasting long-term BMP implementation needs to meet TMDL Waste Load Allocations (WLAs), and 4) demonstration of full trash capture based on a combination of existing and planned BMPs (as project progress allows). The audience will be invited to participate through a Q&A discussion specifying how the LPR model may be implemented to address their watershed specific planning and compliance obligations.

Title: Broadway Neighborhood Greenway Project - Capturing the Water Rights
Presenters: Chris Repp (Los Angeles Department of Water and Power) and Mark Hanna (Geosyntec)
Session: Sustainability Track / Scaling Sustainability
Time: 9:45 - 10:15 a.m. on Wednesday, October 17th
Geosyntec Authors: Kevin Kopp, Mark Hanna
Abstract:
The award-winning Broadway Neighborhood Greenway Project is a regional stormwater and dry-weather runoff augmentation project developed to meet Los Angeles River water quality requirements with an auxiliary benefit of recharging approximately 41 acre-feet per year of water into the Central Basin. The Project, commissioned in 2016, has been actively collecting, treating, and infiltrating stormwater and dry weather runoff for over two years. The successful implementation of this Project was achieved through a partnership between the City of Los Angeles - Los Angeles Sanitation (LASAN, LADWP), the State Water Resources Control Board (SWRCB) - Stormwater Grant Program (SWGP), the Water Replenishment District of Southern California (WRD), The Council for Watershed Health (CWH), Santa Monica Bay Restoration Commission (SMBRC), Los Angeles Department of Public Works Bureau of Engineering (LABOE) and Geosyntec Consultants. Los Angeles Department of Water and Power (LADWP), under the advisory of WRD, has also started the first ever Water Augmentation Project Application for an increase to their annual groundwater pumping rights allocation from stormwater captured in the Broadway Neighborhood Greenway Project and recharged into the Central Basin.

The Broadway Neighborhood is highly urbanized and one of the most densely developed areas of the South Los Angeles region. The neighborhood is south of the I-10 and east of I-110 Freeways. Runoff from the Broadway Neighborhood discharges to the Los Angeles River, an impaired water body due to stormwater and dry weather runoff from dense clusters of commercial, industrial, and residential developments and urban activities. The Project is directly improving LA River water quality, augmenting local water supplies in the Central Basin, and assisting with urban flood management within the neighborhood through the deployment of Low Impact Development (LID) and Stormwater Control Measures (SCMs).

The Broadway Neighborhood Stormwater Greenway Project diverts flows from a 220-acre watershed area for stormwater capture and infiltration through four levels of LID/SCM constructed in private properties, road ends and a under a parking lot. During the initial monitoring period, 96 percent of the equivalent runoff from the Project design area was captured and infiltrated. Additional volume from the upstream tributary area was also captured and infiltrated over the course of the monitoring period, increasing the equivalent capture efficiency to well-beyond 100% of the design capture efficiency. Results of the past two years of monitoring are in progress and will be discussed in the future. In addition, the residential component of the Project continues to help residents conserve water by reducing irrigation demands through turf replacement using drought-tolerant rain gardens, native landscaping, and mulching. The Project provided open space benefits and pedestrian friendly green connections within the community throughout the residential neighborhoods and the commercial district. This Project effectively shows how stormwater and urban runoff is captured and treated on site using the system of LID/SCMs installed, thereby reducing the overall pollutant load from the Project's watershed area and providing a new source of sustainable water to augment the local water supply in the Central Basin.

Title: Nutrient Source Tracking to Support Modification of an Algae TMDL in the LA Region
Presenter: Charles Genkel (Ventura County Environmental Health), Jared Ervin (Geosyntec)
Session: Total Maximum Daily Loads Track / TMDL Compliance Strategies
Time: 2:30 - 3:00 p.m. on Wednesday, October 17th
Geosyntec Authors: Stacey Isaac, Jared Ervin, Brandon Steets
Abstract:
Statewide, TMDL responsible parties are exploring means of modifying TMDL requirements based on new information. In the Ventura River Watershed (Watershed), an Algae TMDL identifies responsible parties including MS4s, general stormwater permittees, ranching, agriculture, and onsite wastewater treatment systems (OWTS). Working closely with the Regional Water Board, the Ventura County Environmental Health Division (VCEHD) sought to pursue a precedent-setting study to spatially define the primary contributing nitrogen sources in the watershed, to support TMDL modification. This study establishes a model for other regulators and dischargers to follow to achieve TMDL modification, and in particular when accounting for hydrologically complex groundwater-surface water interaction-based pathways.

In the Watershed, there are over 2,000 single family residential OWTS, most of which are permitted by the VCEHD. OWTS typically release treated wastewater effluent into unsaturated soil via leach fields, which disperse contaminants prior to reaching groundwater. However, this can potentially impact receiving waters if systems are not maintained or functioning properly, and can also contribute nitrate even when systems properly function. Nitrates can persist in shallow groundwater, which can then flow into surface waters and impact surface water quality.

The Algae TMDL requires all OWTS in the Watershed to reduce total nitrogen loading by 50%. Further, the entire Watershed is initially identified as requiring an Advanced Protection Management Program (APMP), which would require all OWTS to be upgraded to advanced treatment or connected to sanitary sewer, options that potentially represent high costs to private homeowners. However, the TMDL also allows for local agencies to perform an investigation to determine which OWTS are contributing nutrient loading to surface waters. Areas found not to be contributing could be removed from the APMP.
The objective of this State grant-funded study is to define the geographic extent of OWTS that are contributing substantive nutrient loads to the River. More specifically, the study investigates if groundwater nitrogen levels are elevated downgradient of OWTS areas, if those areas are also impacted by sewage indicators that would further support OWTS as a source, and if those impacted groundwaters are also impacting surface water nitrogen levels at upwelling locations.

These questions are addressed by sampling groundwater and instream surface water at representative areas downgradient of OWTS, in addition to control sites. It is anticipated that non-contributing OWTS may be removed from the APMP and no longer require enhanced nitrogen removal, as implemented through a future TMDL reconsideration.

GIS analysis and advanced forensic tools are used, including analysis of chemical sewage indicators and stable nitrate isotopes. Using a tiered approach, lower cost nitrogen compounds are first more broadly screens for, then advanced forensic tools receive targeted use. Results from representative areas are then extrapolated throughout the watershed based on relative risk of OWTS nitrogen impact to surface waters. The end product is a GIS map delineating high risk areas and recommendations for the management of OWTS in the Watershed.
The presentation will include an overview of the study objectives and approach, followed by sampling results and initial conclusions. The study design will be presented as a model for others to follow to similarly define the geographic sources of surface water pollutants through groundwater.
The audience will be invited to participate through a Q&A session on the utility of the study design for other example applications. This presentation is directly related to the conference's theme as it outlines precedent for more targeted pollutant source identification and management, which is a cost-effective means of protecting downstream receiving waters.

Title: Practical Findings from Supplier Surveys, Material Testing, and Column Studies to Improve Biofiltration Media Specifications
Presenters: Aaron Poresky (Geosyntec) and Myles Gray (Geosyntec)
Session: Making Stormwater BMPs Work Track / Media Science
Time: 8:35 - 9:05 a.m. on, Wednesday, October 17th
Geosyntec Authors: Aaron Poresky, Myles Gray
Abstract:
Biofiltration (aka bioretention with underdrains) has emerged as a preferred stormwater treatment option in California and has been demonstrated to meet many stormwater management goals. However, substantial questions remain about biofiltration media specifications for specific pollutants and site conditions. Additionally, field scale monitoring studies have indicated the potential for export of pollutants from biofiltration.  Finally, the cost and quality of materials can vary regionally, which is of specific importance in updates of standard biofiltration specifications that will go into widespread use. 

Recent efforts to improve biofiltration soil specifications in California have included material surveys from regional suppliers, testing of media components, column studies of individual components and combinations, and full-scale design and monitoring projects. Information from these studies, as well as review of past studies in the International Stormwater BMP Database, has provided the basis for updated specifications and/or alternative specifications to achieve higher and more consistent performance for specific pollutants while reducing risks of pollutant export. Through regional supplier surveys, the ability for contractors to supply materials meeting enhanced specifications is inherently vetted.

This presentation will provide a summary of recent and ongoing efforts, including the practical findings that can be transferred to municipalities and project proponents in California. Project examples that will be presented include:
•           Recent media supplier availability and cost surveys and media component testing conducted in the San Diego and Los Angeles Region for municipal and private clients
•           Updates to standard biofiltration media specifications developed as part of three Southern California BMP Design Manuals
•           A column study for a land development project to develop and support an alternative biofiltration media specification

This presentation will summarize recent research findings and lessons learned about putting these findings into practice. The intended audience includes municipal stormwater managers and specifying engineers.

Poster Presenters

Title: Working to Achieve NALs: A Pilot Study Evaluating Use of Flocculant to Reduce Total Suspended Solids and Total Iron Concentrations at a Southern California Landfill
Presenter: Julie Riggio (Geosyntec)
Author: Julie Riggio

More Information

Learn more about the conference: https://www.casqa.org/events/annual-conference.
Read the Journal or Learn more at: CASQA Conference Agenda.
For consultation regarding stormwater planning or quality, contact Ken Suslio at This email address is being protected from spambots. You need JavaScript enabled to view it..