Washington State Phase I county watershed-scale stormwater planning studies: a long term plan to identify stormwater management strategies to improve receiving waters

Washington State Department of Ecology’s 2013-2018 NPDES Municipal Stormwater permittees conducted detailed hydrologic modeling studies to demonstrate how planned development could be accommodated while restoring the beneficial and designated uses to the receiving waters in urbanized watersheds. The jurisdictions used modeling tools including HSPF hydrologic modeling, in-stream ecological targets, and cost optimization tool to determine the most cost effective set of infrastructure to achieve in-stream ecological targets). This talk focusses on the lessons learned from those plans, looking across the plans for similarities and differences. Each of the four counties (Snohomish, King, Pierce, Clark) selected a medium sized (10+ square mile) watershed which included urban growth areas designated pursuant to the Growth Management Act, and therefore known to be under pressure for development in the near future. Counties and cities in Washington are required to plan for and accommodate growth, cities are required to allow high intensity to meet growth targets dictated by the State of Washington. The watersheds had unique characteristics, but all are already partially urbanized. The counties created models to test a suite of strategies in various scenarios to see if water quality standards were, or could be, met. The modeling reports for the three plans submitted so far (King County will submit their plan in spring 2018) showed that current and future stormwater impacts caused by development in these watersheds result in receiving water bodies that do not meet water quality standards, and actions beyond site and subdivision scale of stormwater management will be needed to make receiving waters healthy in urbanized watersheds. The models in all of the watersheds projected that riparian restoration (for temperature) and large amounts of additional stormwater detention and infiltration are needed to improve receiving water conditions. Other in-stream projects (not associated with managing municipal stormwater discharges) were also modeled as having near-term and cost-effective positive outcomes on receiving water bodies. The anticipated costs to recover from these impairments is tens of thousands of dollars per acre for watersheds in Snohomish and Clark Counties. The costs per acre for these typical Puget lowland and lower Columbia developing watersheds are significantly lower than for more developed basins. (City of Kirkland’s Juanita Creek Study estimated costs were approximately $300,000 per acre). While this demonstrates that current permit requirements are having a significant impact, the modeled additional effort to recover the beneficial uses are still well beyond current funding programs and approaches. We encouraged counties to look at the spectrum of strategies available, including structural retrofits, land use strategies and education and outreach. While some of these strategies could not be modeled it was acknowledged that, if properly implemented, they could accelerate the recovery of the receiving water. The basis of the modeling included a hydrologic focus since those stormwater hydrologic impacts on streams have long been acknowledged as the primary loss of salmonid habitat (highest existing beneficial use) in urban receiving waters. Accordingly, some of the common strategies included structural stormwater controls geared towards flow control. For instance, traditional detention was a widely used strategy. Low Impact Development (LID), where feasible, provided a large lift on a smaller relative footprint. If the watershed has infiltrative soils, infiltrating stormwater facilities were the most cost effective. One important strategy that the counties did not highlight in their scenarios was changing the land use designation or zoning codes established as part of the land use comprehensive planning process under the Growth Management Act. Comprehensive planning, and stormwater management are regulated under different laws and overseen by different state and local departments with separate administrative and public processes. Despite knowing that such changes could help protect water quality without the high capital project costs identified by the models, these non-structural strategies are difficult to commit to doing in a short amount of time, are difficult to predict into the future, and receiving water habitat has not to date been a priority in growth management planning. It is difficult for stormwater managers to cross this boundary of authority and responsibility as part of an exercise required by the MS4 permit. Development stormwater infrastructure requirements in western Washington result in stormwater detention and treatment infrastructure that’s intended to mitigate (hydrologic and water quality) development impacts. Due to this construct, cities and counties typically have no design for what their stormwater infrastructure will be, or how it will impacts receiving waters in the future, on a watershed scale. They rely mostly on private investment in stormwater infrastructure improvements needed to have healthy urban receiving waters. Without better long range planning, and a funding source in addition to private investments, and in-stream and buffer improvements, with a focus on what a receiving water needs, the stormwater efforts currently underway will likely not result in healthy urban receiving waters

The perseveration of checking thoughts and mood–as–input hypothesis

This paper describes two experiments designed to investigate how a current model of task perseveration, the mood-as-input hypothesis, might be applied to activities relevant to compulsive checking. The mood-as-input hypothesis predicts that perseveration at an open-ended task will be determined by a combination of the “stop rules” adopted for the task, and the valency of the mood state in which the task is conducted. Experiment 1 required participants to generate items that should be checked for safety/security if they were leaving their home unattended. Experiment 2 used an analogue recall task, in which participants were asked to recall items from a comprehensive list of items that should be checked if they were to leave their home safe/secure. Both experiments found that perseveration at the tasks was determined by particular configurations of mood and stop rules for the task. Of most relevance to compulsive checking was the fact that facilitated perseveration occurred when participants were asked to undertake the tasks in a negative mood using “as many as can” stop rules. Implications for the factors that develop and maintain compulsive checking are discussed

Bioretention Monitoring - Six Full Scale Bioretention Swales

The City of Redmond is in search of a bioretention soil media design standard that can demonstrate good stormwater runoff treatment for wide scale use prior to discharge to surface water or to groundwater. The treatment performance goals: - For discharge to surface waters, remove dissolved copper, dissolved zinc, and total suspended solids. - For discharge to groundwater that is used as a drinking water resource, remove nitrogen. - For discharge to phosphorous sensitive lakes, remove phosphorous. - Remove oils and grease. Bioretention soil must also: - be easy to specify, - be readily available, - be nonproprietary and economical, and - support plant growth. A previous study in Redmond showed poor treatment performance for the Ecology standard mix design of 60% sand and 40% compost. Redmond received a grant from Ecology to perform monitoring of six new full scale bioretention swales using the Technology Assessment Protocol – Ecology (TAPE) , that is used in Washington State for evaluation of emerging technologies for stormwater treatment. The objective of this project is to use TAPE to prove that bioretention can be an effective nonproprietary method of removing pollutants from stormwater runoff. Redmond constructed six swales, each sized to Ecology standards. Each swale was constructed in such a way that stormwater influent and effluent can be monitored. The mix designs to be studied are: - 60/40 Mix. Repeat the 2012 study to see if Redmond got a “bad batch” of compost in that study. - Loamy Sand. Loamy sand is hard to specify, but is commonly used on other parts of the country in bioretention. - Loamy Sand 2. Obtain loamy sand from a second source to identify some variability in performance - Redmond BSM. 60% sand, 15% compost, 15% biochar, 10% shredded bark - Redmond BSM 2. Replicate the Redmond BSM swale. - Redmond BSM 3 (saturated) Replicate the Redmond BSM swale, but incorporate a saturated underdrain zon

Characterization of pollutant flushing from a newly installed bioretention system: 185th Ave NE, Redmond, WA

From February 2012 through September 2013, we conducted hydrologic and water quality monitoring of a bioretention stormwater filtration system at 185th Ave NE in Redmond, Washington. This monitoring was conducted to obtain data that will be used to evaluate if bioretention swales could be used to treat runoff prior to infiltration within a drinking water aquifer recharge area. The study bioretention swale was constructed using the Washington Department of Ecology specified soil mix that consisted of 40 percent compost and 60 percent sand. Eighteen inches of soil mix was installed on top of a six-inch sand blanket underlain by gravel that housed a perforated underdrain pipe. The entire system was lined with an impermeable plastic liner which isolated the underdrain flow from interflow and groundwater entering the swale. Flow weighted composite samples of runoff were collected at an inlet to the swale and from the underdrain. During the first year of study significant export from the bioretention system was observed for all measured nutrients, chloride, hardness, total copper, dissolved copper, and total lead. Bioretention system export during the second year was also characterized by non-significant increases in total Kjeldahl nitrogen, hardness, chloride, and dissolved copper. In addition, one grab sample indicated a large export of methylene chloride in excess of the state groundwater quality standard. During the first six months of operation, the study system exported nitrate+nitrite concentrations in excess of the state groundwater quality standard. The groundwater criterion for fecal coliform bacteria was exceeded at the effluent station during every sampled storm event, even though the study system had a high degree of fecal coliform bacteria removal. No other measured parameters with applicable groundwater criteria were found to exceed criteria in the effluent of the study system. Water extractions of soil mix ingredients (compost, sand, potting soil installed with the plants, and bark mulch) indicated that the compost was the greatest source of nutrients, zinc, and copper, while the sand also contributed levels of concern for zinc and copper. Future bioretention projects should attempt to use sand with lower metals concentrations and composts with lower nutrient and metals content

A Synthesis of Bioretention Performance in the Pacific Northwest

This presentation summarizes and discusses the data from five studies that have been implemented in the Puget Sound region to evaluate the hydraulic and water quality treatment performance of 19 various bioretention soil mixes (BSMs). Bioretention is currently classified in the Stormwater Management Manual for Western Washington (SWMMWW) as a basic (solids removal) and enhanced (copper and zinc removal) treatment best management practice (BMP). However, findings from three studies in 2010-2013 found that bioretention systems built with compost based medias were actually exporting copper as opposed to reducing it. These findings called into question bioretention’s enhanced classification and precipitated further studies of bioretention performance in the region and a look at alternate BSMs. In this synthesis we look at the hydraulic and water quality performance of BSMs classified into four categories 1. 60/40 (sand/compost), 2. 60/40 + Additives, 3. Loamy Sand, 4. Sand/Coir + Additives. The most commonly exported pollutants were copper, nitrogen, and phosphorus. All BSMs performed well for TPH, fecal coliform, and zinc removal. Of the 19 BSMs evaluated in this study, the 60/40 mix was, on average, the worst performing in terms of pollutant flushing and pollutant reduction. Conversely, on average, the best performing BSMs were those that contained Sand/Coir + Additives. Flushing results indicate that by one water year the majority of BSMs have completed their equilibration/flushing period. However, the BSMs with compost tend to export relatively high levels of total phosphorus, nitrate + nitrite, and dissolved copper for at least three water years. A high degree of dissolved pollutant removal is achievable at infiltration rates that exceed the current 2-12 in/hr requirement; however, solids removal suffers at the same high flow rates. It is recommended that compost not be used in BSMs with underdrains and that sand/coir mixes be considered instead