Laserfiche WebLink
IFIengineering <br /> By definition within the Volume 1 of the Everett SWMM, "converted vegetation areas"means any <br /> native vegetation,pasture,scrub/shrub,or unmaintained non-native vegetation that are converted to <br /> lawn or landscape areas. Since the existing field is currently maintained and there are no other <br /> native vegetation areas,there is no converted vegetation areas associated with the project. <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 Plan <br /> (SWPPP) (MR2) <br /> The preliminary CSWPPP 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 /> Everett SWMM that will require the use of source control measures. Stormwater is not anticipated <br /> to come into contact with pollutants within the project area. Also Refer to MR6 description. <br /> Minimum Requirement#4—Preservation of Natural Drainage Systems and Outfalls <br /> (M R4) <br /> In the existing conditions, stormwater for the field area is collected by underdrain system that <br /> generally flows to a catch basin in centerfield,which flows to combined sewer system. The <br /> combined sewer system takes flow off the site near the northeast corner of the site. In the proposed <br /> conditions,the proposed underdrain system will not alter this pattern.The drainage path will <br /> remain unchanged.Refer to the Offsite Analysis section of this report for a description of the <br /> existing downstream drainage course from the field area. <br /> Minimum Requirement#5—On-Site Stormwater Management(MR5) <br /> The synthetic turf field area has been considered as an On-site Stormwater Management Best <br /> Management Practice(BMP). Both the synthetic turf material itself and the aggregate base layers <br /> beneath the field surface are all highly permeable and no surface runoff is anticipated from the <br /> synthetic turf surface. Refer to the field sections shown on Sheet F-2.1,provided within Appendix <br /> A. The synthetic turf material includes a tufted fiber and woven synthetic backing that is <br /> perforated to allow a minimum infiltration rate of 20 inches per hour.The synthetic turf is infilled <br /> with a mixture of rounded sand particles and granulated rubber that do not interlock and are also <br /> highly permeable,with a minimum vertical infiltration rate of 20 inches per hour.Below the <br /> synthetic turf surface is a top course and base course constructed of a specially graded sand and <br /> gravel mixture that results in a permeable aggregate sub-base. The vertical infiltration rates are <br /> tested by an independent third party testing agency after manufacture of the turf. Testing of the <br /> permeable aggregate occurs on site after placement and compaction. <br /> LPD Engineering, PLIC Page 4 Everett Memorial Stadium Baseball Field Replacement <br /> Storm Drainage Report, September 15, 2017 <br />