801 E CASINO RD 2025-07-25 - Laserfiche WebLink

Table 1: Impervious Area Calculations Existing Impervious Proposed Permeable Proposed Impervious Area Areas(sf) Surface(sf) Impervious Area Reduction from with LID Credit(sf) Existing Conditions (sf) 46,394 65,746 32,873 13,521 Based on Table 1, there is a 13,521 square-foot reduction in impervious areas from existing to proposed conditions. Subsequently, the project is not subject to Minimum Requirements #6 through#9 since the following thresholds have not been exceeded: • Creates or adds 5,000 square feet or more of new, replaced, or total of new plus replaced pollutant generating impervious surfaces. • Creates or adds 5,000 square feet or more of new impervious surfaces. • Converts'/4 acres,or more,of native vegetation to lawn or landscape areas. • Converts 2.5 acres,or more,of native vegetation to pasture. The project is subject to Minimum Requirements #1 through #5 based on the following thresholds: • Creates or adds 2,000 square feet, or greater, of new, replaced, or total of new plus replaced impervious surface area. • Has land-disturbing activity of 7,000 square feet or greater. 3.2 Minimum Requirements 3.2.1 M.R.#1 —Storm water Site Plan Preparation The Construction Documents include both existing and proposed drainage plans with associated grading (See Appendix B). The Stormwater Site Plan also includes the contents of this report. 3.2.2 M.R.#2— Construction Storm water Pollution Prevention The project will incorporate erosion and sedimentation control systems to address specific site conditions during construction in accordance with the 2010 Stormwater Management Manual. Because more than 1 acre of area will be disturbed, a Construction Stormwater General Permit will be obtained from the Washington State Department of Ecology. Perimeter control of the construction area will be provided using silt fencing to reduce the risk of sediment transport into adjacent roads and neighboring downstream properties. Ground cover measures and sedimentation tanks are also incorporated into the erosion control design. The full erosion and sediment Technical Information Report Cascade High School—Track Replacement Project 3 Integrityworks Consulting Engineers,LLC Project No.212104