About the Ecomerchant Aquacrate system
Attenuation means to temporarily store stormwater for a period of time, normally until the worst of the storm has passed, the water is then released to the sewer network.
This process uses a “sealed” storage box (attenuation tank) created from our Aquacrate crates with both a geotextile and geomembrane surround as part of a SUDs scheme.
Used as an attenuation system when the normal drainage systems cannot cope with the volume of surface water this is diverted into the attenuation system and released slowly after the storm has passed avoiding localised flooding. Buried 0.5m below the surface connections of any diameter can be made to the system. Ideal in amenity areas and even under car parks and other load bearing areas, Aquacrate is able to take normal traffic loading.
Aquacrate is an extremely strong modular water-permeable polypropylene unit with a large storage capacity.
The Aquacrate has been designed specifically to meet the needs of sustainable construction as advocated by the UK Government and provides the means for rainwater, collected from roofs and pavements, to be infiltrated into the soil. The sewage system is relieved of additional loads and drying out of the sub-surface can be prevented.
- Prevents extreme peak flows to main drainage and water purification systems
- Rainwater is “cleaned” by geotextile surround
- Decreases flooding during heavy rain falls
- Promotes the balance in the groundwater position
- Decreases environmental problems caused by development
- Flexible – can easily be expanded in all directions
- Enables rapid construction of large storage capacities (95% voids)
- Economic to install
- Choice of many diameters for incoming pipes Inlets/Outlets: 110, 160, 200, 225 & 300mm diameter pipes
- Applicable for both high and low groundwater situations
- Housing developments
- Car Parks
- Landscaped Areas
- Recreational Areas
- Amenity Areas
- Caravan Sites
Nominal Size: 0.408m (W) x 0.685m(L) x 0.45m(H), 8 units/ m3, Weight/unit: 6.34 kg (Standard), 5.75 kg (Lite), Vertical Strength: 400kN/m2 (Standard), 200kN/m2 (Lite), Lateral Strength 80kN/m2, volume: 125 litres, Void ration: 95.0%
The above data indicates typical values – comprehensive independent physical test data on the structural and hydraulic properties of the system is available on request.
Following a detailed assessment of the required volume of stormwater to be stored (see CIRIA C522, R156 & BRE 365). The total number of Aquacrate units can be calculated using 8/m3 (950 litres @ 95% void ratio). Decide on the best configuration for the characteristics of the site in question and create the “box” accordingly using the length and width dimensions. As a guide, units require approx 0.5m of cover in landscaped areas and 0.75m cover in vehicular areas with a 75mm sharp sand base.
Aquacrate attenuation cells are specially manufactured, modular cells that provide lots of space (void space, as it's termed) within a lightweight structure that is capable of supporting quite significant loads when buried. Some cells can be placed beneath pavements and are strong enough to carry both foot and low-speed vehicular traffic – our standard crate is heavy duty 400kN/m2 crate we also supply a lighter weight version in our Eco Lite 200kN/m2 crate.
Probably the most relevant regulations regarding site water management will be The Building Regulations part H3 which place emphasis on allowing the surface water to drain into the ground locally where feasible. This is in line with SUDS policy. There are other regulations listed at the end of this article.
SUDS is used as an approach to dealing with rainwater which is particularly relevant to urban areas where there are increasing amounts of hard impermeable areas which tend to send rainwater straight into the drains and thence to the rivers rather than letting the water soak into the ground and get slowly released. During very heavy rainfall this extra runoff overwhelms the drains and causes flash flooding when sewage overflows into becks and rivers. During periods of drought, tree roots can suffer. The idea of SUDS is to hold back the water locally and release it slowly. In addition to attenuation, the most common options are by combining some of the following s
- Using green/living roofs – which delay the speed of runoff
- Using permeable surfaces such as drives and car parking. Several companies manufacture pervious interlocking systems from fully recycled plastic in a variety of grades depending on bearing requirements. The gravel infill can be from recycled crushed hardcore, slate chippings etc.
- Installing a soakaway
- Creating a pond or Swale
- Creating wetlands
- Using lawns – which may be allowed to partly flood
- Installing and attenuation system. These are being increasingly required for new build providing attenuation may be part of your planning approval
Planning Law today aims to avoid inappropriate development in flood risk areas and whilst the risk of flooding cannot be prevented entirely, its effects can be reduced by good practice and the assessment of the risk that any new development poses. Sustainable measures are then included in the design to cater for the potential of flooding during periods of high rainfall.
Aquacrate as an Infiltration System - Soakaway:
Where the surrounding ground is insufficiently permeable to allow the volume of water to infiltrate away naturally, the insertion of a soakaway structure as part of a SUDs scheme (Aquacrate with a permeable geotextile surround) will help this process dramatically by providing an underground void for temporary storage of the stormwater whilst it infiltrates into the surrounding soil.
Used as a soakaway the rainwater is collected from the roof, driveway and hard surfaces fed into the soakaway and then slowly infiltrated into the soil. By infiltrating relatively clean water into the soil, at a relatively slow rate, the drainage system is put under less pressure. Infiltration of rainwater is part of sustainable construction as advocated by the UK Government.
Systems like these have often been part of a commercial SUDs scheme, however, more and more self and custom builders are finding that schemes are required by local authorities, through legislation and often for plots with a number of houses, if you need a SUDs compliant system and would like design guidance just give us a call on 01793 847 444
Don’t forget our super convenient 1m3 pre-wrapped soakaway units, for smaller domestic applications- simple and easy, just place and go!
From just £208 per cubic metre delivered!
Source control principles and techniques, also called Best Management Practices (BMPs), are already forming part of planning controls in some areas and will become increasingly incorporated within new development projects especially with the amended Building Regulations Part H3 coming into force in October this year...
The four basic principles of SUDs
- Don’t hard pave surfaces unnecessarily – make use of porous surfacing materials and grass/gravel reinforcing systems
- Soakaway where possible or attenuate if necessary – this is part of stormwater management
- Improve Water Quality – avoid pollutants entering the watercourse
- Reuse if possible – harvest rainwater and re-use
More guidance / Legislation on SUDs
- PPS 25 – Development and Flood Risk (Issued March 2010), PPS1, PPS3, PPS9 & PPS23
- Future Water – Government water strategy for England
- CIRIA C697 – The SUDs Manual – Best Practice Guidance
- CIRIA C698 – Site handbook for the construction of SUDS
- Flood and Water Management Act 2010 – Management of flood risk by DEFRA
- Surface Water Management Plan – March 2010 giving guidance to Local Authorities
- National Standards for Sustainable Drainage – EA, LA’s & House Builders working together
- Pollution Prevention Guidelines – Controlling pollution at its source
- Building Regulations Part H3 – including 2010 amendments. This will be superseded by this updated and amended version on October the 1st
Trade and private inquiries welcome