TagACC(1531)

Placeholder page for Exhibit 2203, AR 034782.02, indicating the document was not present at the time of scanning. No substantive content available; administrative record reference only.

Exhibit 2202, AR 034782.01, was not present at the time of scanning. This is a placeholder page indicating a missing document in the administrative record. No content is available for this exhibit.

This document presents a Water Resources Analysis Schedule, displayed as a Gantt-style project timeline chart. It outlines the sequencing and duration of various technical tasks related to water resources analysis, including data collection, feasibility studies, treatment evaluations, and report preparation. The schedule appears to track project milestones and dependencies across multiple phases of a water resources planning effort.

This document outlines Washington State Department of Ecology's presumed policy positions on stormwater mixing zones, addressing when stormwater becomes regulated state water and how mixing zones should be calculated. It details recommended design storms for acute and chronic mixing zones, critical receiving water flow conditions, and background concentration requirements. The document also discusses circumstances under which mixing zone size criteria exceedances may be permitted under state regulations.

This document contains hydrological flow data for Miller Creek, including a ranked frequency analysis of the lowest monthly mean streamflows recorded between August and May from 1948 to 1995, alongside modeled daily and hourly stream flow outputs from 2-year/72-hour and 2-year/2-hour storm events simulated in August 1996. The analysis identifies a 5-year mean low flow of approximately 0.60 cubic feet per second for the lowest month in the August–May period. Acute and chronic water quality standards are also evaluated in relation to effluent and receiving water flows during the storm event.

National Research Council publication by the Committee on Mitigating Wetland Losses, Board on Environmental Studies and Toxicology, and Water Science and Technology Board titled ‘Compensating for Wetland Losses Under the Clean Water Act.’ AR034586, Exhibit-2178. Covers mitigation compliance standards including jurisdictional hydrology, wetland delineation, hydrological performance standards, design standards for mitigation sites, USACE wetland filling

This document presents a statistical analysis of ambient water conditions and effluent discharge at a location designated 3RWN, examining the joint probability of stream flow and discharge occurring simultaneously. It includes a 3D probability surface chart, a data table showing dilution factors ranging from 3.6 to 5,294 at various probability levels, and a distribution curve of ambient stream discharge measured in cubic feet per second. The analysis notes that effluent is present approximately 38% of the time, with the 7Q10 flow of 0.16 cfs corroborating the 1st percentile and the 5Q30 flow of 0.15 cfs corroborating the 0.9th percentile.

Exhibit 2141 was not present at time of scanning. Administrative Record number AR 034564.02. No substantive content available; placeholder page only.

This Washington State administrative regulation establishes rules for 'mixing zones,' which are designated areas in bodies of water where pollutant discharges are allowed to mix and dilute before meeting water quality standards. The rules set strict size limits for mixing zones in rivers, estuaries, lakes, and ocean waters, and require that dischargers apply all available pollution-reduction technology before a mixing zone is approved. Special provisions are also included for storm water discharges and combined sewer overflows.

This technical document from a March 25 meeting discusses stormwater mixing zone analysis for proposed outfalls around Seattle-Tacoma International Airport (STIA). Because standard stream flow conditions (7Q10 and 30Q5) are extremely unlikely to coincide with stormwater discharge events, Parametrix proposed a site-specific approach using higher-probability rainfall-based discharge combinations instead. The analysis found that reasonable dilution of 14- to 24-fold could occur within about 15 to 20 meters downstream, though complete mixing requirements would exceed standard regulatory width and flow percentage criteria, prompting a request for exceptions under WAC 173-201A-100.