Na

Source: Lung, 1991.

Notes: (1) River miles are the distance measured from confluence of James River with Chesapeake Bay. (2) Petersburg is 10.8 miles upstream from the James River.

Notes: (1) River miles are the distance measured from confluence of James River with Chesapeake Bay. (2) Petersburg is 10.8 miles upstream from the James River.

gional treatment plants. In the early 1980s, all POTWs achieved secondary treatment levels except the Lambert's Point plant, which was considered at an advanced primary level (with phosphorus removal). Since the early 1980s, wasteload allocation studies have been prepared to recommend further reductions of the BOD5 loads in the upper estuary. Some of them, such as those in the Hampton Roads Sanitation District, achieved BOD5 concentrations in the effluent much lower than 30 mg/L.

A study by the Virginia SWCB showed that the phosphate detergent ban has resulted in reductions of total phosphorus concentrations of 34 percent for POTW influent and 50 percent for effluent (SWCB, 1990). The SWCB's analysis was based on the data collected from the POTWs operated in the Hampton Roads Sanitation District, which operates nine POTWs in the James River basin. The total phosphorus concentrations measured during different periods of the study are shown in Table 9-3.

It should be pointed out that the analysis shown in Table 9-3 was based on the POTWs that did not have phosphorus removal. The phosphate detergent ban would have no effect on the effluent phosphorus concentration from the POTWs that remove phosphorus. Eventually, when the POTWs remove phosphorus to meet the 2 mg/L requirement, the ban will reduce the costs of phosphorus removal by reducing the influent concentrations.

The upstream boundaries and tributaries of the watershed of the estuary account for approximately 94 percent of the drainage area measured below the confluence of the James and Chickahominy rivers. The area adjacent to the Appomattox and James

Figure 9-6 Locations of major point source discharges to the James estuary. Source: Lung and Testerman, 1989. Reprinted with permission of The American Society of Civil Engineers. Copyright 1989.
TABLE 9-3 Effect of Phosphate Detergent Ban: Hampton Roads Sanitation District

Time Period

Influent (mg/L)

Effluent (mg/L)

0 0

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