03/10/2004 ZONING BOARD OF APPEALS Minutes

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Southside Realty Trust Engineering Review Page three 5. emergency shut-down for possible spill containment. There is no further mention of what the emergency shutdown procedure is or how the containment is handled. 6. Page 7, paragraph 4 indicates that riprap slope protection is to be used at certain points within the drainage system. It is not clear where these will be placed or how they are to be constructed. 7. Page 7, Stormwater Operation and Maintenance Post Construction: A maintenance plan as required by the DEP Stormwater Regulations is included. However, there is no mention of what entity will be responsible for the operation and maintenance of the drainage facility or if regular reports will be generated or to whom they might be submitted. If there is a spill or other routine maintenance is required who will do the work or notify the proper authority? 8. The drainage calculations include a determination of pre- construction runoff from the site as well as post-construction runoff from the finished project. Both sets of calculations were done using a generally accepted HydroCAD computer program. Plans of the watersheds are included in the report. Post development runoff calculations assume sources will be impervious surfaces, forest areas or grass. No mention is made of whether building roofs and drives are included in the numbers shown on the land coverage tables. The drainage area plan seems to indicate that they may be. Please verify. There is also no mention of those areas that would be covered in wood chips. • These areas would need a separate curve number and infiltration rate and should be figured into the calculations. Calculations indicate, however, that there is a significant increase in stormwater runoff from the site due to the increase in impervious surfaces. Surfaces not covered by forest or grass may increase runoff even further. 9. Drainage calculations indicate that infiltration is the primary source of stormwater disposal with a secondary disposal method being through the use of broad crested weirs. The infiltration uses bioretention facilities that include planting areas, gravel curtain overflows and grass filter strips. The infiltration depends on open, porous soil conditions for proper functioning. It is not clear where the broad crested weirs discharge or what the receptors are. There is a substantial concern that during winter months there will not be sufficient drainage through the natural soils to adequately handle the storm water runoff. This year has been exceptional for frozen ground conditions however it is quite possible that even a mild winter could have frozen ground for a period of time when infiltration is nearly zero. What provisions have been made to address potential flooding or runoff leaving the site under these conditions? There is a significant concern that the dramatic topography of this site will generate runoff at a rapid rate that cannot be handled by • bioretention methods only.