Reference Document MCU22/0102 Stormwater Management Plan

5.2. CAR WASH WASTE WATER TREATMENT SYSTEM
A detailed description of the Car Wash Waste Water treatment system is as follows;
2,000L Silt pits will be installed in the Automatic Wash Bays which will be connected into a series
(4 pits in total) of twin reclaim pits (~4,000L capacity each), which will be connected to the
Recycle System. To cater for of effluent overflow; the final reclaim pit will also be connected into
a minimum 12,000L Holding Pit. For effluent recycling from the Automatic Wash Bays to occur,
the recycle unit will be placed in the Plant Room (with duty and stand-by pumps). Refer to
Appendix D for details of the Reclaim unit.
2,000L Silt pits will be installed in each Self-Serve and Super Wash Bay which will discharge into
the minimum 12,000L Holding Tank. The Holding Tank will have a duty and standby pump to
pump the effluent water to the Oil Water Separator. The Oil Water Separator will treat the
effluent water to the acceptable level and then discharge via gravity into the site’s sewer
discharge location (TBC with Unity Water). The Oil Water Separator will be a Fox Environmental
FX10,000 unit that will operate at a 7,200 L/hr maximum treatment capacity. This FX10,000 unit
is an oversized unit (based on the expected maximum effluent volume to be treated) which has
been selected to ensure the minimum 12,000L Holding Tank will be required to store minimal
effluent- even when the site is functioning at its maximum potential.
All on-site sanitary/Dog Wash effluent water will connect into the sewer discharge pipe after the
Oil Water Separator. Each Dog Wash tub will be fitted with a suitable hair trap that is cleaned on
a weekly basis.
Particular attention to the Car Wash wash bay design has been given so that no waste water or
effluent escapes from the wash bay areas and discharges into the stormwater system. This is
achieved by giving all wash bays a 100-200mm minimum fall from the perimeter of the wash bay
to the silt pit in the centre of the respective bay. Also, the roofed areas over all Self-Serve and
Super Wash Bay areas have a suitable roof overhang (minimum of 1.0M) to prevent stormwater
from entering into the wash bays and thereafter into the sewer system. There is a strip drain
provided at the exit of the Automatic Wash Bays and the entry area of these wash bays is also
contained in a bunded and drained area (via 600L Silt Pits) to help with water from escaping
from this entry area. The silt pits between the Automatic Wash Bays and between the Self-Serve
Wash Bays and Super Bays will be interconnected with pipes to prevent any overflow of effluent
water escaping from these wash bays.
The car wash will operate as a five-star water rated Car Wash. The car wash equipment used at
this facility is rated under the Car Wash/State Government water rating scheme. A trade waste
discharge licence will be obtained from Unity Water prior to construction commencing.




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