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Update on Jordan L,alce Nutrient Management Strategy <br />September 17, 2004 <br />Page 4 of 5 <br />Table 2. <br />Annual Mass Load Limits and Effective Concentrations <br />Currently Proposed By DWQ <br />Permitted Total N itrogen Total Phosphorus <br />Flow Mass Load Limit Concentration Mass Load Limit Concentration <br />MGD (Pounds) (mg/L (Pounds) (mg/L) <br />12.0 135,669 3..71 10,501 029 <br />14.5 135,669 3.07 10,501 0.24 <br />18.5 135,669 2.41 10,501 0.19 <br />22.5 135,669 1.98 10, 501 0.15 <br />The equivalent TN and TP concentration limits at future flows of 18..5 and 22.5 mgd <br />(which is the estimated ultimate orbuild-out flow for OWASA) shown in Tables 1 and 2 <br />represent the practical limits of current wastewater treatment technology. OWASA staff <br />remains confident that the improvements currently underway will enable the Mason Farm <br />Plant to meet the stringent new limits at flows of 14.5 mgd and probably beyond. This <br />will be further enhanced by the OWASA/UNC wastewater reuse system, which will <br />reduce the effluent volume -and therefore the total nutrient load -discharged to Morgan <br />Creek. <br />Under DWQ's proposed management strategy, all dischargers to the Upper New Hope <br />Arm of Jordan Lake (OWASA, Durham, Durham County, plus several small private <br />facilities) would be subject to the same equivalent concentration limits. Annual mass <br />load limits would vary with the maximum permitted flow (volume) for each respective <br />facility. Because of Jordan Lake's unique hydrology, and as reflected in results of the <br />Nutrient Response Model, wastewater dischargers in the Haw River arm of the watershed <br />would be subject to different (less stringent) nutrient limits.. <br />Enforcement of Point Source TN and TP Limits <br />DWQ has two principle approaches for administering and enforcing the amoral mass load <br />limits for point sources. One is to enforce the limits on afacility-by-facility basis, as is <br />currently done. The other is to enable point source dischargers to form a group <br />compliance partnership, and to issue the partnership a special "mnbrella" permit based on <br />the total allowable TP and TN mass loads for all the pazticipating facilities. Under that <br />approach, all dischargers would be considered in compliance as long as the group did not <br />exceed the allowed cumulative total. A group compliance approach has been <br />implemented in the Neuse River Basin, and participants believe that such an approach <br />offers flexibility and "insurance" in achieving the collective point source nutrient load <br />reduction targets for that basin <br />to <br />