Durham Tech Facilities Building - SSW-SuppEZ_2018.09.17-1707

SAND FILTER1 Drainage area number1 Total coastal wetlands area (sq ft) - Parking / driveway (sq ft)47948 sfTotal surface water area (sq ft)62866 sf - Sidewalk (sq ft)2560 sfTotal drainage area (sq ft)1093052 sf - Roof (sq ft)13241 sfBUA associated with existing development (sq ft) - Roadway (sq ft)Proposed new BUA (sq ft)63749 sf - Other, please specify in the comment box below (sq ft) Percent BUA of drainage area6%Total BUA (sq ft)63749 sfDesign rainfall depth (in)1.0 inMinimum volume required (cu ft)776 cfDesign volume of SCM (cu ft)840 cf#1 Is the SCM sized to treat the SW from all surfaces at build-out? Yes#7 If applicable, with the SCM be cleaned out after construction?Yes#2 Is the SCM located on or near contaminated soils? No#8 Does the mainetenance access comply with General MDC (8)?Yes#3 What are the side slopes of the SCM (H:V)? n/a#9 Does the drainage easement comply with General MDC (9)?Yes#3 Does the SCM have retaining walls, gabion walls or other engineered side slopes? No#10 If the SCM is on a single family lot, does the plat comply with General MDC (10)?#4 Are the inlets, outlets, and receiving stream protected from erosion (10-year storm)? Yes#11 Is there an O&M Agreement that complies with General MDC (11)?Yes#5 Is there a a bypass for flows in excess of the design flow? Yes#12 Is there an O&M Plan that complies with General MDC (12)?Yes#6 What is the method for dewatering the SCM for maintenance?Pump (preferred)#13 Was the SCM designed by an NC licensed professional?Yes #1 SHWT elevation (fmsl)lower than 336.75' #3 Volume of stormwater from drainage area during design storm (cubic feet) 776 cf#1 Type of sand filter (open or closed) Closed #3 Total volume that can be stored above the sediment and sand chambers (cubic feet) 840 cf#1 If closed, describe if the filter will be pre-cast or pour-in-place: #3 Is this sand filter designed to attenuate peak flows? No#3 Elevation of the bypass device (fmsl) 337 ft#1 If closed, top of grate elevation (fmsl) 341 ft#2 Volume that can be retained in the sediment chamber (cubic feet) 420 cf#2 Will there be a permanent pool in the sediment chamber? Yes#2 Bottom of the sediment chamber (fmsl)331 ft#4 Ponding depth from the top of the sand to the bypass device (ft) 5 ft#2 Area of the sediment chamber (square feet)105 sf#2 Physical depth of the sediment chamber (inches) 90 in#2 Ponding depth in the sediment chamber, above any permanent pool (inches)54 in#2 Elevation of top of weir between chambers (fmsl)333 ft#2 Volume that can be retained in the sand chamber (cubic feet) 420 cf#2 Bottom of the sand chamber (fmsl) 331 ft #7 Depth above underdrain pipe (inches) 12 in#2 Area of the sand chamber (square feet)105 sf#8 Will the media be maintained to drain at least two inches per hour at the sand surface? Yes#2 Physical depth of the sand chamber (inches) 90 in #9 Is at least one clean-out pipe provided at the low point of each underdrain line? Yes#2 Ponding depth in the sand chamber, above any permanent pool (inches)54 in#9 Will clean-out pipes be capped? YesTHE DRAINAGE AREAGENERAL MDC FROM 02H .1050Break down of BUA in the drainage area (both new and existing):COMPLIANCE WITH THE APPLICABLE STORMWATER PROGRAMStormwater program(s) that apply (please specify):Phase II and Jordan Lake RulesPlease use this space to provide any additional information about this sand filter that you think is relevant to the review:SAND FILTER MDC FROM 02H .1056ADDITIONAL INFORMATIONWeir from Sediment chamber to Sand chamberpre-cast#3 Describe the bypass device:#5 Describe the mechanism for distributing flow over the sand surface:#6 Sand specification for sand chamber Cleaned, washed, coarse masonry sand, such as ASTM C33. The sand particles shall be less than 2mm average diameter.Splitter box with weir set at water quality elevationDurham Tech Facilites BuildingSand Filter13:47 PM 9/17/2018