WasteWater
For further information
please contact:
Christchurch City Council
City Water & Waste Unit
Technical Services Team
PO Box 237
Ph: (03) 941-8830
Fax: (03) 941-8384
Email: [email protected]
http://www.ccc.govt.nz/TradeWaste
May 2003
TRADEWASTE
TWI 11
Washdown
Area > 15 m2 with
Separation System
Washdown Area > 15 m2
with Separation System
Drawing 11E
WHY
do we need it?
The runoff from surfaces like roofs, yards, roads, driveways
and other waterproof surfaces is channelled into the
stormwater pipes through stormwater grates in road
gutters, yards and parking lots. The stormwater pipes carry
this runoff away to discharge into the nearest stream, lake,
underground soakhole or beach. This means that any wastes
that get into stormwater pipes will end up in our streams
or groundwater aquifers, and can cause:
•
Direct threat to wildlife and ecological systems
•
Release of toxic or poisonous fumes in the sewer
•
Fire and explosion
•
Water quality degradation used for domestic water
supplies and stock watering.
WHO
needs to install it?
All commercial premises that wash down cars or other
equipment frequently. Examples of such premises are car
yards, mechanical workshops, car groomers, fuel stations
and vehicle/other wash facilities.
1
Notes (Sheet 11E)
1. The model of EL-O-MATIC actuator used is dependent
upon water pressure available.
- Less than 3.5 bar use model ED200.
- More than 3.5 bar use model ED100.
2. Mount the control box in a position readily accessible to
the operator. The switch MAIN VALVE is to be exposed to
view at all times and to have permanent, easily read labels
as shown.
3. Install in a position readily accessible and free from the
likelihood of mechanical damage.
4. The bleed should drain to a position that will not endanger
the electrical controls.
5. The BURKERT interface and electric solenoid valve should
be mounted together in a suitable enclosure, which may
be attached to the electrical control box.
6. The MAIN VALVE ON/OFF switch may be replaced with
a timer adjusted to suit the wash needs.
7. The RPZ is to be mounted above ground (min 300 mm)
and protected from frost.
10
Stormwater Petrol & Oil Interceptor
Drawing 11D
Legal requirements
•
•
•
Christchurch City Trade Wastes Bylaw
New Zealand Building Code G13 – Foul Water
New Zealand Building Code G14 - Industrial Liquid Waste
You need to have a Trade Waste Consent to discharge to the
sewer and require operation controls to be in accordance
with an approved Environmental Management Plan. Because
the installation of the washdown area involves drainage
alterations, a Building Consent is also required.
Size and design
Notes:
1. “S” = Maximum trapping capacity of solids/silt
2. “F” = Maximum capacity of floatables, eg
petrol/oil etc.
Notes (Sheet 11D)
1. Provide standard concrete precast manhole cover and
cast manhole lid.
2. Top of interceptor to be level with surrounding finished
ground level. This interceptor is for the WASHDOWN
AREA facility only.
3. Gully trap not required. Piping system from here on to be
to requirements of BIA E1 except that disposal to a soak
pit is not acceptable unless specifically approved.
4. Vent manhole to a safe position 3 m above ground (Ref:
BIA G14 2.2.4). Use 37 mm steel pipe.
9
The general design is outlined in the accompanying drawings.
Larger versions are available from our webpage
http://www.ccc.govt.nz/TradeWaste.
Before installing the washdown area you need to discuss your
design and further requirements with a Technical Services
Officer at the Civic Offices.
The design incorporates a butterfly valve that is available with
a range of liners from which a type can be chosen to suit the
nature of the effluent. When the pad is in operation the valve
opens automatically diverting all discharges to the sewer. The
valve shuts automatically when the operation ceases thus
preventing stormwater discharges to the sewer.
One approved configuration is:
• Butterfly valve: “Value”, 100mm
• Actuator: “EL-O-MATIC” (model to suit)
• Interface: “BURKERT” Model 413 – 230 Volt AC
Other proprietary manufactured valves may be suitable for
this purpose but may only be used if they:
• Are a recognised brand.
• Are noted for reliable operation.
• Have a local ready supply of spare parts and service
personnel.
• Are approved by the Christchurch City Council Technical
Services Office.
Maintenance
It is the occupier’s responsibility to ensure the wash pad is
maintained in effective working order. If the pad is not
maintained, the occupier may be liable for any costs of damages
to the sewer and the Trade Waste Consent may be withdrawn.
2
Associated drawings
Drawing 11A
Notes (Sheet 11C)
1. Minimum acceptable size is 1 m3 working capacity. For
Humes type 1050 diameter this corresponds to 1155 cm
of depth below the invert level of the sewer outflow pipe.
Size interceptor relative to the amount of solids expected
in relation to desired frequency of cleaning by authorised
Liquid Wastes contractor.
The Technical Services Officer reserves the right to require
a high liquid level alarm if considered necessary. This alarm
may also be required to render the wash inoperative.
2. Vent manhole to a safe position 3 m above ground (Ref:
BIA G14 2.2.4). Use 37 mm steel pipe.
3. Provide standard concrete precast manhole cover and
cast manhole lid.
4. Top of interceptor to be level with the surrounding finished
ground level.
5. Gully trap may be remote from interceptor.
6. Piping system from here on to be to the requirements of
BIA G13. If invert levels are such that compliance with BIA
G13 cannot be achieved then install a pumped system to
BIA G14 2.4.3 figure 2(b).
7. The butterfly valve actuator and interface are available
from Taylors Ltd 360 Tuam ST, Christchurch. A double
acting actuator is to be used EL-O-MATIC type ED. An
ED100 will suffice for most situations but if water pressure
is below 3.5 bar then fit an ED200. Other manufacturers’
products may be suitable but are to operate in the same
manner and are subject to approval by the Technical
Services Office. See sheet 5 for water supply and electrical
content.
3
8
Sewer petrol & Oil Interceptor
Drawing 11C
Notes (Sheet 11A)
1. Gradient such that the flow velocities will prevent the
settlement of solids and grit in the pipeline (min 1:40, Ref:
BIA G14 2.1.3).
2. Piping system to be to the requirements of BIA G13. If
invert levels are such that compliance with BIA G13 cannot
be achieved then install a pumped system to BIA G14 2.4.3
figure 2(b).
3. Piping system to be to the requirements of BIA E1 except
that disposal to a soak pit is not acceptable unless specifically
approved by the Christchurch City Council.
4. Maximum carry distance to sumps is 6m (Ref: BIA G14).
See sheet 2 for details of sump.
5. Draining directions shown thus. Gradient to be 1 in 40 or
better (Ref: BIA G14 2.2 (b)).
6. Sumps to have easily removable perforated steel plates 8
mm thick and hole sizes 10 mm max at 50 mm centres to
prevent entry of stones etc to drainage system. Plates to
be resistant to corrosion.
7. Slab to be concrete and of suitable strength to withstand
anticipated usage. Surface to have smooth float machined
surface to aid drainage. The top of the slab to be higher
than the finished level of the surrounding land.
8. If wash overspray is likely to cause nuisance to others or
unacceptable pollution levels then provide spray screens
each side of wash.
Notes:
1. “S” = Maximum trapping
capacity of solids/silt
2. “F” = Maximum capacity of
floatables, eg petrol/oil etc.
9. It is preferable to position petrol and oil interceptor on
sewer as close to wash slab as possible to maximise available
gradient and so facilitate drainage of solids to interceptor.
7
4
Drawing 11B
Notes (Sheet 11B)
1. Grating to be 8 mm steel plate with 10 mm circular holes
at 50 mm centres. Grating to be resistant to corrosion
and in suitable lengths to enable easy lifting for cleaning
purposes.
2. This is bottom of draining channel at entry to sump. The
200 mm corresponds to 1 in 40 grade at a travel distance
of 5 m to the sump for the wash slab shown on sheet 1.
3. Bottom of sump to be hunched as shown to direct silt to
sewer petrol and oil interceptor.
4. The top of both interceptors is to be level with surrounding
finished ground level. The wash slab is to be above the
surrounding finished ground level.
5. Pipe size 100 mm diameter and gradient to be such that
the flow velocities will prevent the settlement of solids and
grit in the pipeline Ref: BIA G14 2.1.3.
6. Piping system from here on to be to the requirements of
BIA G13. If invert levels are such that compliance with BIA
G13 cannot be achieved then install a pumped system to
BIA G14 2.4.3 figure 2 (b).
7. Piping system from here on to be to requirements of BIA
E1 except that disposal to a soak pit is not acceptable
unless specifically approved.
5
6