Bulahdelah Sewage Treatment Plant

Environment Protection Licence #5305
The Bulahdelah sewage treatment plant Environment Protection Licence (# 5305) stipulates concentration limits for specific water quality parameters from treated effluent prior to discharge. The Bulahdelah licence has a range of concentration limits listed including 50 percentile, 90 percentile and 100 percentile limits. These limits relate to the monitoring of results throughout the licence period.

 

To meet a 90 percentile limit, the monitoring results must not exceed the specified concentration limit for 90% of the time during the monitoring period. Likewise, 50 percentile concentration limits are to be achieved for 50% of the results throughout the monitoring period. The 100 percentile limits are not to be exceeded, alternatively the maximum concentration.

 

The Bulahdelah licence monitoring period is reported upon annually with a 6th of December anniversary. As a condition of the licence the treated effluent is monitored monthly. Discharge concentration limits are specified for: biological Oxygen demand (BOD); total suspended solids (TSS); faecal coliforms (FC); total phosphorus (TP); ammonia; oxidised nitrogen and ph. The corresponding concentration limits stated in the licence for each of these parameters are listed in Table 1.  
 

Table 1.Bulahdelah licence effluent concentration limits for Biological Oxygen Demand, Total Suspended Solids, Total Phosphorus, Faecal Coliforms, Ammonia, Oxidised Nitrogen, pH, Oil and Grease.

Bulahdelah STP
EPA I.D point No 1.
Discharge to waters
BOD
TSS
TP
FC
Ammonia
Oxidised Nitrogen
pH
Oil & Grease
mg/L
mg/L
mg/L
cfu/100ml
mg/L
mg/L
pH units
mg/L
50%ile
Limit
8
10
0.3
90%ile
Limit
10
15
0.5
0.5
100%ile
Limit
20
30
1.0
200
1.0
10
6.5-8.5
10