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STORMWATER SITE PLAN 8/18/2023 <br /> SOUTHWEST STORAGE YARD 6 <br /> Along the western flow path,the ditch line along the dike to the north would also be engaged by storage volumes during <br /> an event. LiDAR indicates the ditch bottom is in the 2-4 elevation range, similar to the storage area to the south.This <br /> would indicate that both sub basins would benefit from the additional storage. <br /> See Figure 5: Downstream Elevations for the layout. <br /> An SCS Unit Hydrograph was used to estimate the volume difference in runoff between the current conditions (Pasture) <br /> vs the proposed conditions (Impervious).The print out of the basin and results is included in Appendix B,the results are <br /> summaries as follows: <br /> 100 year Existing Basin Runoff Volume: 21,232 cf <br /> 100 year Developed Basin Runoff Volume: 25,730 cf <br /> The difference is 4,498 cf. <br /> The grading for the previous Sea Con project to the east provided 78,000 cf of additional storage as part of its mitigation. <br /> The site only utilized 50,600 cf, leaving an additional unclaimed 27,400 cf.Thisis more than adequate to compensate for <br /> the 4,498 cf increase. <br /> MR 8: WETLANDS PROTECTION <br /> There are no wetlands on or near the development site. <br /> MR 9: OPERATION AND MAINTENANCE MANUAL <br /> An Operations and Maintenance Manual is provided under separate cover. <br /> P:\Work\Projects\2021\21-162 Sea Con\CE\DOCS\STORMWATER SITE PLAWSMALL.doa <br />