Category: Environment

The disposal of slurry and waste concrete poses a potential risk of environmental harm if not managed appropriately. Creating and maintaining a designated wash-down area allows for contractors to correctly wash down equipment whilst reducing the risk of pollution to waters or land.

Managing concrete washout

Concrete wash water is alkaline (with a pH of around 12) and contains substantially high levels of Chromium, with the potential to harm and pollute land as well as seep into the ground and contaminate groundwater. Concrete washout material, if not managed effectively can increase the pH of surrounding waters in addition to posing potential harm to aquatic life and pollution to waters, including storm water.

Effective concrete washout facilities are used to contain liquids and concrete slurry when the chutes of concrete mixers and hoppers of concrete pumps are washed out after delivery to a site. These washout facilities are utilized to combine solids for simpler reuse or disposal and the prevention of contaminated runoff liquids. Solids that are wrongly disposed of can clog water drain pipes – resulting in flooding. Installing and utilising washout facilities not only assists in the prevention of water pollution but is also considered simply a matter of “good housekeeping” on construction sites. 

Location and management of washout areas

The following management measures should be considered to reduce the potential risks of concrete washout areas on the environment:

• The washout area should be situated away from storm water drains, drainage lines and bodies of water.
• The concrete washout area should be conveniently located for washing out equipment and clearly indicated.
• All wash down water is to be contained within the designated watertight bund.
• Concrete washout areas are typically not designed for the gathering of excess concrete. Excess concrete waste should be returned to the local batching plant for treatment and re-use, or placed in a site receptacle designated for concrete and masonry, and allowed to set.
• To reduce the quantity of washout water produced, excess concrete should be scraped off the equipment before it is washed and placed in a site receptacle suitable for masonry and concrete.
• A high pressure, low volume water spray nozzle is recommended to reduces excessive water use.

Monitoring

All concrete washout areas should be maintained and monitored to safeguard that they are fully functioning and have adequate storage capacity.

Monitoring should be undertaken as a minimum:

• Weekly during dry weather
• Prior to forecast rainfall events
• During rainfall events
• As soon as practical following the event of rainfall.

Set concrete should be removed to reinstate capacity to the washout area and prevent overflows.

Environmental Incidents

Lastly, any environmental incidences should be reported. An environmental incident emerges if concrete is washed out in an area other than the designated concrete washout area.

If you are interested in talking to the experts in concrete washout, get in contact with one of out concrete washout solution specialist at info@pumperdump.com.au or by using the PumperDump App (App Store) (Google Play) 

 Ref: Extracted from the NSW Government’s Concrete Washout Guidelines 

Advice from the CCAA. New South Wales has over 300 active concrete batching plants that produce numerous concrete by-products and wastes. The NSW legislation and regulations require that all operators remain committed to minimising the amount of new resources used during the production process, to ensure that as much material as possible is recycled or re-used, and any waste which cannot be re-used is disposed of appropriately and ethically.

More often than not, many concrete by-products can be re-used in the concrete batching process without breaching any of the existing environmental regulations. The CCAA has developed a document to provide guidance on the regulatory requirements for managing the four main concrete by-products. These products are specifically known as:

Concrete By-Product	Definition
1. Hardened Returned Concrete	Hardened Returned Concrete is concrete that has been returned to a concrete plant and has been cured and hardened. Hardened Returned Concrete contains the same properties as normal concrete and is largely free of contaminants, such as wood, cementitious materials, paper, steel reinforcement, plastic and brick. Once hardened, this concrete can be handled and stored with little risk of contaminated water runoff.
2. Concrete Wash Water	Concrete Wash Water has a high pH (near 12), which makes it highly alkaline, and it also has an excessive matter of suspended solids. Concrete Wash Water is the product produced from washing pumps, trucks, chutes and mixers or simply cleaning out and agitator bowl and hosing down the batch plant yard.
3. Liquid Wash / Slurry	Liquid Wash Out is an unavoidable by-product of the concrete batching. The washout slurry descends to the bottom of settling ponds and tanks in concrete plants which makes it extremely challenging to pump and transfer. It is also an alkaline material which is exceptionally difficult to re-use in the concrete batching process as it is not a consistent product and it re-use presents numerous concrete performance and technical issues.
4. Solid  Wash Out	Solid Wash Out has the consistency of clay and is returned concrete that has been washed out and dried. It is a mixture of sand and aggregates from the original concrete, and contains hydrated lime and other cementitious materials which sources alkalinity. This material is generally taken out of washout pits, drained, dried, transported to quarries or recycling centres and recuperated for re-use.

Ref: Extracted from the NSW Government’s Concrete by-product Recycling and Disposal Industry Guidelines

How to Deal with Different Types of Concrete By-Product

1. HARDENED RETURNED CONCRETE 

General Exemptions Re-use

Hardened Returned Concrete can be crushed at facilities that have the applicable licences to form recovered aggregates. In this manner it can re-used in the concrete batching process, or applied to the land as engineering fill or as road base.

This material can be applied to road construction on private land if the following conditions are met:

• Development consent for the development has been approved under the appropriate Environmental Planning Instrument.
• The relevant waste is applied to land at the smallest degree necessary for the construction of a road.
• It is to provide access (permanent or temporary) to a development approved by a local government.

The material being applied to the land must be sampled and tested, to ensure that it will pose marginal threat or harm to the environment.

Hardened Returned Concrete cannot be utilised for the following applications:

• Quarry, mine and sand dredge rehabilitation
• Dams
• Back fill for voids
• Utilised in reshaping land for agricultural purposes.

2. CONCRETE WASH WATER 

Re-use and Recycle

Concrete Wash Water is generally stored on-site at a concrete batch plant in settling ponds and is recycled into the concrete batching system. This process is advisable as it also reduces the requirement for clean mains water in the concrete batching process.

3. LIQUID WASH OUT / SLURRY 

Liquid Wash Out is categorized as liquid waste material. As such, this waste is required to be transported by licensed contractors in specialized “sucker trucks”, designed for this task specific task, and disposed of at licenced facilities. 

Re-use and Recycle

Liquid Wash Out can be stored in settling ponds, which are stressed to keep the material in a state of suspension. The Liquid Wash Out or Slurry is maintained as such, in its liquid state. The water can then be pumped out and recycled back into the batching process, whilst leaving the majority of the cementitious alkalinity material in the settling pond.

Disposal

If Liquid Wash Out cannot be kept in a state of suspension, the material will collect at the bottom of the settling pond, requiring it to be pumped out and disposed of at a licensed facility.

Transform

The final option for dealing with Liquid Wash Out is to change it from liquid waste into solid waste. This is an advisable process as it;

• increases the number of disposal sites licensed to accept the waste
• increases the ease of handling the waste
• decreases transport costs and disposal fees.

One procedure applied for transforming the waste from a liquid to a solid, is to pump the slurry into dewatering tubes for geofabric bags.

4. SOLID WASH OUT 

Disposal

Solid Wash Out does not require a licensed transported and does not entail tracking. Nonetheless, if the material is to be disposed of, it needs to be transported to a licensed facility. At the licensed facility, Solid Wash Out is either re-processed into sand and gravel, it is mixed with various other materials to either fill another product or become road-base.

If you are interested in optimising the way you deal with different types of concrete washout, get in contact with one of our experts for a more efficient and environmentally friendly solution at 1300 366 668 or by using the PumperDump App (App Store) (Google Play) 

Ref: Extracted from the NSW Government’s Concrete by-product Recycling and Disposal Industry Guidelines 

The concrete pumping contractor has a responsibility to ensure that all staff and/or subcontractors act in ways that do not cause environmental harm through spillage or leakage of concrete. It is the responsibility of the concrete pumping contractor to ensure concrete residue and/or washdown residue from their activities does not contaminate drains or waterways. Clean-up of all equipment, including the receiving hopper, pipelines and hoses, must also be done in a manner that does not contaminate drains or waterways. 

Wash-down water produced during clean-up of equipment must be disposed of in a manner that does not and will not contaminate nearby drains, waterways or soil. It is the responsibility of the concrete pumping contractor to manage the disposal of excess concrete and wash-down water generated during the pumping and clean-up operation. Disposal to the sewer system is not permitted without prior consultation with the local sewage authority. 

Purpose

Proper management during the pumping of concrete can minimise the risk of any detrimental impact on the environment.

Applications

• for concrete pumping contractors working on construction sites
• for site managers overseeing concrete-pumping activities

Best management practices

• Where possible, concrete pumping equipment should be set up on the construction site. This reduces the potential of leakages from hoppers, hoses and fittings that could contaminate the stormwater system. 
• Ensure adequate protective screens are erected around the pump area to prevent concrete splashing into street gutters or stormwater drains.
• Where possible, ensure the pumping of concrete occurs at a location on the site where any spillage will not contaminate the stormwater system.
• Where a concrete pump is located on a roadway or footpath where excess material could enter the stormwater system, appropriate bunding to trap spilled material should be installed. Portable concrete collection units (plastic or metal trays or receptacles) should be placed under pumping equipment to collect any spilled material during works (see figure 2).
• Hoses, hoppers, wheelbarrows and other equipment must be washed in the site wash-down area after all excess material has been removed by hand.
• Excess and residue concrete from the hopper and line should either be collected and sent back with the delivery truck or placed in the site’s designated concrete
• masonry recycling receptacle.
• To minimise the amount of wash-down water generated, scrape excess concrete residue from the hopper before washing. Do not wash out the hopper directly into the street gutter.
• It is the responsibility of the concrete contractor to properly manage the disposal of wash-down water generated during the cleaning process. Options for collection, treatment and disposal of wash- down water should be discussed with the site manager.
• Wash-down water from the hopper must not contaminate the stormwater system. The wash-down area should be used only for small volumes of wash-down water and is not to be used as a disposal point.
• Mud, soil and stones carried off-site are regarded as pollutants. Therefore, tyres and undercarriages must be clean before vehicles leave the construction site.

Inspection and maintenance

• Inspect and maintain the machinery regularly to minimise leaks and drips.
• Pollution controls should be in place before concrete is pumped. The concrete pump contractor should inspect pollution controls to ensure they are adequate, and should liaise with the site manager if there are any problems. •The site or project manager or delegate must maintain vigilance during the work activities to ensure that pollution control procedures are being followed.
• Placing equipment or material where it is likely to pollute the environment may result in on-the-spot fines or prosecution.

Get in contact with one of our field experts for a more efficient, cost-effective and environmentally friendly solution at 1300 366 668 or by using the PumperDump App (App Store) (Google Play) 

Ref: Extracted from the NSW Government’s Environmental Best Management Practice Guideline for Concreting Contractors