1710 W MARINE VIEW DR 2024-01-03

Maintenance Standards . Remove sediment from the pond when it reaches 1 foot in depth. . Repair any damage to the pond embankments or slopes. BMP C250: Construction Stormwater Chemical Treatment Purpose This BMP applies when using chemicals to treat turbidity in stormwater by either batch or flow - through chemical treatment. Turbidity is difficult to control once fine particles are suspended in stormwater runoff from a con- struction site. BMP C241: Sediment Pond (Temporary) is effective at removing larger particulate matter by gravity settling, but is ineffective at removing smaller particulates such as clay and fine silt. Traditional Construction Stormwater BMPs may not be adequate to ensure compliance with the water quality standards for turbidity in the receiving water. Chemical treatment can reliably provide exceptional reductions of turbidity and associated pol- lutants. Chemical treatment may be required to meet turbidity stormwater discharge requirements, especially when construction proceeds through the wet season. Conditions of Use Formal written approval from Ecology is required for the use of chemical treatment, regardless of site size. See https://fortress.wa.gov/ecy/publications/SummaryPages/ecy07O258.htmI for a copy of the Request for Chemical Treatment form. The Local Permitting Authority may also require review and approval. When authorized, the chemical treatment systems must be included in the Con- struction Stormwater Pollution Prevention Plan (SWPPP). Chemically treated stormwater discharged from construction sites must be nontoxic to aquatic organ- isms. The Chemical Technology Assessment Protocol - Ecology (CTAPE) must be used to evaluate chemicals proposed for stormwater treatment. Only chemicals approved by Ecology under the CTAPE may be used for stormwater treatment. The approved chemicals, their allowable application techniques (batch treatment or flow -through treatment), allowable application rates, and conditions of use can be found at the Department of Ecology Emerging Technologies website: https:Hecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-permittee- guidance-resources/Emerging-stormwater-treatment-technologies Background on Chemical Treatment Systems Coagulation and flocculation have been used for over a century to treat water. The use of coagu- lation and flocculation to treat stormwater is a very recent application. Experience with the treatment of water and wastewater has resulted in a basic understanding of the process, in particular factors 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 396