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.~=i~uq;~ Pii!1?''- weir of the diversion vault. l=or units possessing a sizable depth below grade (depth to pipe}, a single manhole access point vrould aliavr both sump cleanout and access behind the screen. GDS Technologies Recommends The Follavring: NEW tNSTALLATfONS -Check the condition of the unit after every runoff event far the firs# 30 days. The visual inspection should ascertain that the unit is functioning properly (no blockages or abstractions to inlet andJor separation screen}, measuring the amount of solid materials that have accumulated in the sump,, the amount of fine sediment accumulated behind the screen, and determining the amount floating trash and debris in the separation chamber. This can be done with a calibrated "dip stick" so that the depth of deposition can be tracked. Schedules far inspections and cleanout should be based on storm events and pollutant accumulation. ONGC~ENG QPERATION - During fhe rainfall season, the unit should be inspected at least ante every 30 days. The fioatatles should be removed and the sump cleaned when the sump is 75-$5°1© full. If flaatables accumulate more rapidly than the settleable solids, the floatables should be removed using a vactar truck or dip net before the layer thickness exceeds one to two feet. Geeanout of the CD5 unit at the end of a rainfall season is recommended because of the nature of pollutants collected and the potential for odor generation from the decomposition of material collected and retained. This end of season cleanout will assist in preventing the discharge of pore water from the GDS unit during summer months. uSE C3F SQRBE1w1TS - It needs to be emphasized that the addition of sarbents is not a requirement for CDS units to effectively control oil and grease from storm vrater. The conventional oil baffle within a unit assures satisfactory oil and grease removal. However, the addition of sarbents is a unique enhancement capability special to CDS units, enabling increased oil and grease capture efficiencies beyond that attainable by conventional oil baffle systems. Under normal operations, GDS units wi11 provide effluent concentrations of oil and grease that are less than 15 parts per million (ppm} for all dry vreather spills where the volume is less than or equal to the spill capture volume of the GDS unit. During wet weather flows, the ail baffle system can be expected to remove bet<rreen 40 and 7d% of the free oil and grease from the storm water runoff. CDS Technologies only recommends the addition of sorbents to the separation chamber if there are specific land use activities in the catchment ~ratershed that could produce exceptionally large concentrations of oil and grease in the runoff, concentration levels well above typical amounts. If site evaluations merit an increased control of free oil and grease then oil sarbents can be added to the CDS unit to thoroughly address these particular pollutants of concern. Exhibit B-2