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111 <br /> engineering p c <br /> The project proposes more than 2,000 square feet but less than 5,000 square feet of new plus <br /> replaced hard surface;therefore, based on Figure I-2.4.1, Minimum Requirements#1 -#5 will <br /> apply. Based on this determination, water quality and flow control will not be required, but the <br /> project will be subject to meeting requirements for On-Site Stormwater Management(OSM). <br /> Below is a description of each of the minimum requirements that apply to this project. <br /> Minimum Requirement#1 — Preparation of Stormwater Site Plans(MRI) <br /> This document is the Stormwater Site Plan. It outlines the existing and proposed site and drainage <br /> conditions, describes the stormwater management system, and presents the stormwater analysis. <br /> Minimum Requirement#2—Construction Stormwater Pollution Prevention (SWPP) <br /> (MR2) <br /> The Construction Stormwater Pollution Prevention Plan is included in Appendix C of this report. <br /> Minimum Requirement#3 —Source Control of Pollution (MR3) <br /> There will be no proposed or applicable activities matching those listed within Volume IV of the <br /> 2014 SWMMWW that will require the use of source control measures. Stormwater is not <br /> anticipated to come into contact with pollutants within the project area. <br /> Minimum Requirement#4—Preservation of Natural Drainage Systems and Outfalls <br /> (MR4) <br /> The existing downstream drainage path will not be altered or adversely affected as a result of this <br /> project. The existing on-site storm drainage system will remain in-place,thus not altering any of <br /> the natural drainage systems. <br /> Minimum Requirement#5—On-Site Stormwater Management(MRS) <br /> On-site Stormwater Management Best Management Practices (BMPs)will be evaluated per chapter <br /> V-5 of Volume V of the 2014 SWMMWW. <br /> OFFSITE ANALYSIS <br /> A field inspection was conducted by LPD on February 2,2019 to verify the on-site conditions, <br /> downstream drainage paths, and upstream basins. The following Offsite Analysis was based on the <br /> City of Everett's "Map Everett"interactive mapping tool and the site investigation. <br /> From the project site, the drainage map is as follows; <br /> 1. Stormwater collected by onsite drainage systems is conveyed and discharged to a catch <br /> basin on the east side of the proposed portable location, where it then flows northwest 117 <br /> LF through a private 12-inch corrugated metal pipe to an existing storm catch basin. <br /> 2. The flow is then conveyed 158 LF westerly though a private 12-inch corrugated metal pipe <br /> to a manhole located outside of the fence at the southwest corner of the play area. <br /> 3. From there,the water is discharged into a swale located west of the project area via 40 LF <br /> of 21-inch corrugated metal pipe. <br /> LPD Engineering, PLLC Page 4 Horizon Elementary School — Classroom Portable Installation <br /> Storm Drainage Report,June 5, 2019 <br />