S8.E requires Phase I Municipal Stormwater Permittees to measure the effectiveness of stormwater management
actions or practices. The intent of this monitoring program is to investigate whether or
not a specific action is making difference in achieving the goals of the
stormwater program. This component requires Permittees to design a
monitoring program to answer effectiveness questions, identify an action or
suite of actions, identify a targeted environmental outcome and include a
hypothesis about the study.
Ecology required Phase I Permittees to develop Quality Assurance Project Plans (QAPPs). The following describes each Phase I Permittee’s effectiveness study with links to each QAPP.
King County is evaluating the effectiveness of a ditch retrofit program to improve stormwater quality. The County is evaluating a low impact development (LID) Best Management Practices (BMP) for reducing peak flows of stormwater to streams and other surface waters. The County is also evaluating cost effectiveness of tested BMP designs as an alternative to more traditional stormwater treatment.
Snohomish County is evaluating the effectiveness of a Pet Waste Campaign to determine its effectiveness for reducing fecal coliform bacteria to the urban stormwater system. The County is conducting stormwater monitoring and surveying behavior change. The goal of this study are to detect a 50% difference in the seasonal or annual geometric mean of fecal coliform concentrations in stormwater with 90% confidence based upon outreach efforts conducted after the first year of sampling.
Clark County is evaluating the effectiveness of a public educational campaign focused in high density residential areas. The County’s campaign will educate residents to reduce fertilizer and pesticide use. This action evaluates collection of pesticide, herbicide and nutrient stormwater data coupled with a pre- and post- behavior survey. This study is conducted in two neighborhoods with one neighborhood serving as the control. Data will be analyzed to determine whether the campaign is reducing fertilizer and pesticide use. Results from the study will help determine whether residential users can reduce pollutant loads to stormwater by maintaining right-of-ways.
Pierce County is investigating the use of sodium chloride (salt) for roadway snow and ice control and its possible effects on adjacent waterbodies. Pierce County will concurrently assess the corrosion effects salt may have on vehicles and roadway infrastructure. Monitoring information from this study will be used to inform Pierce County’s Road Program and staff responsible for applying salt to roadways. This study will help determine standard operating procedures needed to address the use of chloride applications in the County. The County is also evaluating whether salmon carcass placement activities are beneficial to salmon populations and associated stream biological health. Results of the study will help guide the development and implementation of similar carcass placement projects in other streams in Pierce County. The County will evaluate relationships between BIBI scores and the benefits of re-establishing ocean nutrients from active salmon carcass placement in streams.
City of Tacoma
The City of Tacoma is evaluating their basin-wide storm system cleaning approach in the Thea Foss drainage area. This study focuses on cleaning stormwater conveyances and catch basins to determine whether this action achieves reductions in contaminant concentrations. The City is evaluating this effort (basin-wide cleaning) in conjunction with their source control program to enhance sediment quality discharged into the Thea Foss Waterway.
City of Seattle
The city of Seattle is determining pollutant loading reduction from use of regenerative-air street sweepers. The city is also measuring the distribution of pollutants removed by particle grain size fractions. The results from this study will provide a tool for evaluating sweeping as an operational control versus a capital improvement project (stormwater treatment). Seattle is performing analysis to increase their understanding of the distribution of contaminants by various grain size fractions for each waste stream: street dirt, sweeper waste, and catch basin sediment. The data results will help the city develop a tool to predict a relative targeted annual load reduction for varying conditions (sweeping frequency, road surface condition, and parking enforcement compliance). This study will build upon the Seattle Street Sweeping Pilot Study that was conducted in 2006. The Street Sweeping Pilot Study was conducted to investigate whether street sweeping can be effective in reducing the effect of city outfalls on sediment quantity and quality in the offshore receiving environment. The study found that street sweeping is effective in reducing the amount of sediment and associated pollutants discharged from city streets and served as the catalyst for an expanded street sweeping program in Seattle. For the follow up to the pilot study, see the Program Effectiveness Report: Street Sweeping for Water Quality:
Port of Tacoma
The Port of Tacoma is evaluating the effectiveness of increased source control and training efforts. The focus is evaluating the effectiveness of a training program for employees and an educational program for drayage trucking customers. The results from this study may improve Port maintenance activities, help to prioritize areas for additional stormwater controls, enhance enforcement actions for an anti-idling policy to reduce diesel particulates from drayage trucks and improve employee training and education and outreach for customers.
Port of Seattle
The Port of Seattle is analyzing the effectiveness of their tenant education program and monitoring the effectiveness of improved maintenance. This study evaluates behavior change by distributing educational materials to Port tenants. The Port hopes to improve tenant understanding of stormwater permit requirements, potential impacts from stormwater discharges to receiving waters, and methods for minimizing and eliminating illicit and non- stormwater discharges. The Port will also monitor the effectiveness of improved sweeping and catch basin cleaning. These activities will be evaluated for their net benefit to water quality enhancement. The results will be used to improve the Port’s annual maintenance program.
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