Sewage treatment
63 Sewage treatment
Sewage treatment (the relevant activity) consists of—
operating 1 or more sewage treatment works at a site that have a total daily peak design capacity of at least 21EP; or
operating a sewage pumping station with a total design capacity of more than 40KL in an hour, if the operation of the pumping station is not an essential part of the operation of sewage treatment works to which paragraph (a) applies.
The relevant activity does not include—
carrying out works, other than operating a sewage pumping station mentioned in subsection (1)(b), involving only infrastructure for the collection of sewage, including, for example, pipes; or
carrying out works involving either of the following—
operating or maintaining composting toilets;
treating or recycling greywater; or
operating no-release works.
In the following table, the aggregate environmental score for the relevant activity is the score stated opposite the threshold within which the relevant activity is carried out.
| Threshold | Aggregate environmental score | 3 |
|---|---|---|
| 1 operating sewage treatment works, other than no-release works, with a total daily peak design capacity of— | ||
| (a) 21 to 100EP— | ||
| (i) if treated effluent is discharged from the works to an infiltration trench or through an irrigation scheme; or | 14 | |
| (ii) otherwise | 27 | C |
| (b) more than 100 but not more than 1,500EP— | ||
| (i) if treated effluent is discharged from the works to an infiltration trench or through an irrigation scheme; or | 27 | |
| (ii) otherwise | 53 | C |
| (c) more than 1,500 but not more than 4,000EP | 76 | C |
| (d) more than 4,000 but not more than 10,000EP | 89 | C |
| (e) more than 10,000 but not more than 50,000EP | 114 | C |
| (f) more than 50,000 but not more than 100,000EP | 125 | C |
| (g) more than 100,000EP | 145 | C |
| 2 operating a sewage pumping station mentioned in subsection (1)(b) | no score |
In this section—
daily peak design capacity, for sewage treatment works, means the higher EP for the works calculated using each of the following formulae—
EP = V / 200 where—
V is the volume, in litres, of the average dry weather flow of sewage that can be treated at the works in a day;
EP = M / 2.5 where—
M is the mass, in grams, of phosphorus in the untreated influent that the works are designed to treat as the inlet load in a day.
no-release works means sewage treatment works from which neither solid nor liquid contaminants are released to the environment, whether from inside or outside the works.
operating, sewage treatment works, includes—
collecting gas from the treatment works; and
operating a pump station or other works associated with the treatment works.
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