STORMWATER ATTENUATION
.

AquaCell:

- the CONTROL SOLUTION for - Water run-off, Flooding & Excess surface water

• Controlled, reduced-volume release of storm water into existing sewer systems or watercourse.

• Molloy’s supply hydrostatically controlled out-flow restrictors for storm water attenuation solutions that comply with Local Authority requirements.

• Significantly reduces the risk of flooding.

• Molloy Precast design and construct small to large scale storm water attenuation systems according to clients needs.

• Sustainable, cost effective management of the water in the environment.
  
  

AquaCell (Blue) Non trafficked area: Vehicles up to 2500kg gross mass: -up to 3 cell units wide in trench - more than 3 AquaCell units wide Maximum depth to base of unit 0.5m 0.6m 0.75m 4.1m Designed and developed for areas subject to heavy traffic loading and for large projects Proven vertical loading capacity 56 tonnes/m sq Proven lateral loading capacity 7.75 tonnes/m sq Designed for both shallow and deeper installations Aqua Cell (Blue)

AquaCell Lite (Green) Non trafficked area: Vehicles up to 2500kg gross mass: -up to 3 cell units wide in trench - more than 3 AquaCell units wide Maximum depth to base of unit 0.3m n/a n/a 1.5m Designed and developed for landscaped and other traffic-free areas where heavy loading is not required Proven vertical loading capacity 17.5 tonnes/m sq Proven lateral loading capacity 4 tonnes/m sq Specifically designed for restricted depth Aqua Cell Lite (Green)

• Dimensions: 1m x 0.5m x 0.4m

• Suitable for both soakaway and storage tanks

• Lightweight and versatile

• Holds 190 litres of water per unit – 95% nominal void ratio

• Safer option than open or above ground storage structures

• Easy to install and handle

• Allows “brick-bonding” assembly for extra stability: no extra adaptors needed

• Proven clip and peg system to secure units
  

How AquaCell/Lite work:

• Storm water exceeding the capacity of the conventional drainage system is attenuated by the control manhole and channeled into the AquaCell unit assembly

• The internal structure of each unit is designed to bring surging water under control and hold it in temporary storage

• If the wrap that envelopes the unit assembly is impermeable, the water will remain in the unit assembly until such a time as it can flow back into the control chamber and discharge through the outflow control
  
  
• However if the wrap is permeable, the temporarily stored water may be released into the surrounding ground; soil conditions permitting
  
  
• By controlling the storm water at source and recharging the local groundwater it not only eases the pressure on conventional drainage systems but benefits the local environment as well
  
  

• Rainfall is naturally captured by vegetation and soaks into the soil

• Even if there is surface run-off vegetation and ditches can delay the waters arrival to the river for hours,
  even days (large areas)

• SuDS will ensure the natural process of rainwater soakage to ground water occurs
  
  
• SuDS reduces the extent of erosion and sediment transfer and the associated transport of pollutants from
  natural surfaces to the river system
  
  

• Slower run-off collection through over land flow to ditches, interception swales (grassed channels) and
  filter drains

• Promotion of infiltration through the use of swales, assisted by filter drains and infiltration basins (e.g.
  porous pavements)
  
  
• Storage systems for both volume attenuation and treatment whereby ponds and wetlands are used to hold
  back discharges to streams and rivers to reduce flows and facilitate the removal of solids and pollutants
  though sedimentation and other processes, both physical and biological

The idea is that water is left on-site to soak away. If interceptors are specified for a site, they must be located before the storm water attenuation area and a slit trap should be fitted.

Storm water attenuation can be used in 2 ways

• To promote infiltration on site, where there is no risk to groundwater, by using a permeable membrane to wrap the AquaCells

• To store the rainwater in the AquaCells, by using an impermeable membrane, until it can flow back into the control chamber and be discharged through the outflow control to the County Council storm drain
  
  

• The test pit should be dug at the proposed location of the infiltration system.

• If primary calculations indicate that a dimension of the infiltration system will be larger than 25m long a
  second pit should be used.

• For tanks or infiltration pits larger than 25m further test pits would required every 25m.
  
  
• If a big variation of infiltration is suspected then test pits should be spaced every 10m.
  
  
• The test pit should be at the same approximate depth as that anticipated in the full size infiltration system
  with 0.5m3 of water from areas <100m2 and 1m3 for >100m2 .