Following is the letter sent to SPU from the Ballard Stormwater Consortium’s Technical Advisor, Kim McDonald, listing the Consortium’s concerns:
24 November 2014
Betty Meyer, SEPA Responsible Official
Seattle Public Utilities
Seattle Municipal Tower, Suite 4900
PO Box 34018
Seattle, Washington 98124-4018
Re: Ballard “Natural Drainage Systems” 2015 SEPA Determination of Non-Significance
Dear Ms. Meyer:
The Ballard Stormwater Consortium grew out of neighbors concerns in how Seattle Public Utilities was addressing stormwater issues in the Ballard CSOs. Having worked with neighbors to resolve the malfunctioning rain gardens initially installed in 2010, Ballard Stormwater Consortium began building a collaborative relationship with Seattle Public Utilities to find productive and successful means to reduce and possibly eliminate CSO events from Ballard into Salmon Bay.
Since 2012, Ballard Stormwater Consortium has met with SPU staff and technical experts as SPU began looking to again site rain gardens in the Loyal Heights/Sunset Hill neighborhoods of Ballard. We have monitored soil testing, infiltration tests, observed testing of currently established rain gardens, and suggested effective modes of outreach. We were also instrumental in the establishment of a Citizen Advisory Council expanded to include the Greenwood, Fremont, Wallingford as well as Ballard neighborhoods. This CAC has representatives from the industrial areas along the Ship Canal, leadership of the Ballard District Council, Fremont and Wallingford Chambers of Commerce, and community centers, as well as a representative from the Ballard Stormwater Consortium. It is tasked with advising SPU as they proceed in developing recommendations for the Protecting Seattle’s Waterways plan.
While our concerns have been consistently discussed with representatives of Seattle Public Utilities, we are submitting these comments to the Determination of Non-Significance.
Our concerns are as follows:
1. The environmental checklist states that the combined sewer overflow problem for the Ballard CSO areas, is 15 million gallons. The rain gardens intended to be installed will, at best, detained or slow down flow, of only 96,000 gallons, meaning this project will assist in only addressing .64% of the problem. The cost-benefit is minimal.
2. The detailed analysis of the underlying soils continue indicate evidence of Vashon Glacial Till, essentially clay, which is impervious to infiltration at any rates sufficient to make the rain gardens function according to best management practices and Department of Ecology requirements. While the testing indicates area of higher infiltration rates, these areas are scattered throughout the target area and because of the lack of concentration, make the success of the rain gardens problematic.
3. The checklist indicates that SPU has not determined the flow of groundwater. Significant studies have indicated that infiltration or pit drain based rain gardens contribute significantly to groundwater and have been known to cause “perched water.” In addition, the while there is some evidence the rain gardens may “filter” toxics contained in the stormwater from street run off, significant testing done in rain gardens in Kirkland, Washington, have shown that greater particles of zinc, copper, and other toxics leech out of the rain gardens than seem to be inputted. Ground water will be significantly altered with rain garden leeching. In Ballard, stormwater flows into Shilshole and Salmon Bays. These rain gardens have a higher probability of contributing to toxic levels in those two important bodies of Puget Sound.
4. This checklist contains incorrect information. Best Management Practices for rain gardens require the bioretention soil to be removed every 5 years. The SEPA checklist indicates every 15 years. Where the toxic soil will be disposed was also not addressed in the SEPA checklist, bringing up questions of environmental justice in it’s disposal.
5. Apparently the goal of the project is to mimic natural groundwater hydrology prior to urbanization. It is a laudable goal. However, the reality is the city and specifically the Ballard area, is urbanized, and attempting to mimic pre-urbanized hydrology over small areas of land is creating a “display” rather than a functioning non-urbanized forested system.
6. The SEPA checklist admits that the bioretention soils create a toxic sludge. The recommendation in the checklist is to advise residents these rain gardens are not recreational sites. However, a number of the rain gardens will be sited next to an elementary school and a community center, both which provide critical programming to children in K-5 age groups. Few things are more attractive to children than mud and puddles. Children may have constant and consistent exposure to a number of toxic residues because of the location.
7. Rain gardens do in fact attract mosquitoes and water-attracted insects. Health issues regarding the concentration of those insects have been widely emphasized by the Seattle-King County Department of Health. While the rain gardens may be designed to drain within 72 hours, similarly designed rain gardens, those which replaced the malfunctioning rain gardens from Phase 1, have lingering and standing water in them and in the curb cuts, long after 72 hours from storms.
8. Nothing in the SEPA checklist addressed the modeling done by SPU for increased intensity and volume of storm events due to climate change.
Again, thank you for the opportunity to comment. Please advise us of any further developments in this project.
Technical Advisor, Ballard Stormwater Consortium