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Shallow Attenuation Tank for Constrained-Depth Stormwater Storage
Our shallow attenuation tank range gives you four module heights, from 85 to 250 mm, with 95% void space. AQUA Rain Water supplies the modules, interlocks and supporting lining materials for your specified underground stormwater storage layout.
- 1000 × 500 mm footprint
- 100% recycled polypropylene
- Model and document review
Black shallow attenuation module with moulded support structure
Shallow module construction with upper and lower panels.
Four heights
85 / 150 / 200 / 250 mm
Layout footprint
2 units per m², per layer
Material
100% recycled PP, black
Production
Approximately 15 days
Inspection
Dimensions, appearance and compression
Supply support
Material coordination and loading supervision
AQUA Rain Water Shallow Geocellular Storage for Restricted Excavation
AQUA Rain Water supplies low-height module systems where available depth restricts conventional underground storage. For installation in courtyards, landscaped spaces or a proposed car park, use the required storage volume and the available depth after paving, cover and base layers have been accounted for.
Match height to footprint
A 150 mm layer provides 142.5 L/m² of calculated void storage and a 250 mm layer provides 237.5 L/m²; the thinner you choose your crate, the more area you need to store the same volume of water.Keep the complete build-up visible
The height of your tank is only one element of the excavation. Talk to your designer before deciding upon the module, regarding the formation level, groundwater, all other utilities, and your finishing level.
The trade-off is depth versus area: a thinner module does not always fit a constrained site better. Use our module quantity calculator for geometric capacity and the depth worksheet to compare your specified layers; these tools are not a substitute for hydraulic or structural design.
Materials for Attenuation, Infiltration and Reuse
Our modules use 100% recycled polypropylene with a standard black finish. We coordinate geotextile and geomembrane as supporting procured products, alongside the ordered modules and connectors.
Lined detention
Storage is provided by the impermeable geomembrane together with protection geotextile; runoff is stored temporarily by the attenuation system, with discharge from a separately designed outlet controlled to suit the downstream drainage network.
Infiltration
The modules are separated from adjacent soil by the permeable geotextile. Install the soakaway in this configuration only where ground conditions allow water to infiltrate without an unacceptable groundwater or pollutant risk.
Non-potable storage
A rainwater harvesting system needs appropriate treatment, controls and pumping, together with a complete sealed storage system. Water designated for reuse cannot also be counted as vacant stormwater detention capacity.
Module Assembly and Drainage Interfaces
Modules are formed by 2 moulded top and base panels that clip into place around a series of internal supports; adjacent modules are connected horizontally via separate interlocks. A module is not intended to be reopened once assembled.
Installation Process
- Siting Plot up the scheme. Plan both modules orientation, their required positions, the perimeter of their installation, along with where the joints should be connecting in accordance with site plans.
- Coordinate The connections in pipework and/or channels are project-specific installation tasks for the drainage contractor, clarify what services need coordinating prior to ordering.
- Lay out the space The area must have space to cater for both initial pre-treatment and any resultant discharge via flow control facilities, and crucially for subsequent site access/cleaning.
- Make preparations for future maintenance Silt must be collected prior to entry into tank, then access to maintain/clean has to be readily provided to required components.
A flow control device, such as a prescribed vortex flow unit or an orifice, controls the release of stored contents from the underground detention system.
ARW-SA
Interlocking System
Review Your Connection Layout
Shallow Tank Selection Matrix
AQUA Rain Water’s four ARW-SA models share a 1000 × 500 mm footprint. Compare the model dimensions and calculated capacity first, then have the installed configuration checked for your surface load and design life.
| Parameter | ARW-SA-85 | ARW-SA-150 | ARW-SA-200 | ARW-SA-250 |
|---|---|---|---|---|
| Length, mm | 1000 | 1000 | 1000 | 1000 |
| Width, mm | 500 | 500 | 500 | 500 |
| Height, mm | 85 | 150 | 200 | 250 |
| Void ratio | 95% | 95% | 95% | 95% |
| Calculated storage, L/unit | 40.375 | 71.25 | 95 | 118.75 |
| Calculated storage, L/m² | 80.75 | 142.5 | 190 | 237.5 |
| Units/m² per layer | 2 | 2 | 2 | 2 |
INFO: Capacity basis: external length × width × height × 0.95. Effective detention volume depends on operating water levels, connected components and the approved hydraulic layout; it can be lower than geometric void volume.
Load Grade
Compression and installed loading
Short-term ultimate compression alone is not an allowable project load, as failure-test conditions and the installed structure are not equivalent. A load review requires the selected model, lateral restraint, cover, traffic, groundwater and long-term performance; EN 17150 and EN 17151 address different compression-test timescales.
- Short-term compression failure in tests is not, by itself, a load basis for project design.
- Do not convert a laboratory failure result into a project traffic class.
- Including traffic expected in service alongside construction vehicles is necessary when reviewing loading for car parks and parking lots.
- Please request the model-specific document list with your design team.
Pricing, Production and Shipment
Our quotation covers the selected model, quantity, connectors, lining materials and packing arrangement. Production takes approximately 15 days; freight transit and destination handling are separate from that production period.
01
LOAD CRITERIA
Compare the complete load scope
Unlike a laboratory result, a design load accounts for safety factors and service conditions; using incorrect criteria for the load specification leaves a risk despite a suitable model fit within the area and available space.
02
COST ANALYSIS
Include the site costs
Excavation, spoil disposal, wrapping, pretreatment and future cleaning affect whether a shallow layout is cost-effective. Our quotation scope checklist helps you identify missing line items without assuming a saving percentage.
Our team reviews product configuration and packing before loading. Loading supervision and photographic reporting can be arranged.
Quality Control and Factory Inspection
Our core moulded-product operation uses 82 injection-moulding machines and two-shift production. Before shipment, we use approximately 2% batch sampling for moulded products, covering dimensions, colour, appearance and compression.
03
INSPECTION SPEC
Witness the inspection
We have in-house compression-test capability. Factory-witnessed tests or test video can be arranged, with the selected product and inspection scope agreed before the visit.
04
DOCUMENTATION
Review the order documents
We coordinate product-related documentation with the shipment scope. An internal inspection record and a third-party test report serve different purposes; request the document list relevant to the selected model.
We would rather review your cover, loading and outlet requirements before the order than leave those questions to the installation crew.
How We Work: Layout Review to Product Supply
SYS-LAYOUT_REVIEW
Site Conditions Requiring Another Layout
A proper design for any suds (sustainable urban drainage systems) scheme must include maintenance access in the initial design layout and identify who is responsible for future maintenance including cleaning works, in other words it will require an operator, not simply the provider of the module parts. When creating a shallow system layout for urban areas, ensure the ground depth below the finished level accommodates the full system construction height; review the configuration if initial ground constraints hinder a structurally checked and maintainable installation for subsurface stormwater management systems.
- Insufficient footprint for the required effective volume.
- High groundwater or poor infiltration conditions.
- No acceptable downstream outlet or overflow route.
- Runoff quality requiring treatment before storage.
- Cover or base layers cannot fit the available depth.
- Traffic or construction loads lack a project check.
- Underground parking competes with the tank footprint.
- Inspection components would become inaccessible.
Engineering Tools & Calculators
Depth Budget Calculator
Evaluate site constraints, cover requirements, and invert levels to determine the optimal layout depth for shallow attenuation systems without compromising structural integrity.
Quotation Scope Checklist
Ensure complete project cost accuracy. This checklist helps you identify necessary line items such as excavation, spoil disposal, wrapping, and pretreatment.
Shallow Volume Estimator
Quickly calculate the required geocellular storage capacity and physical footprint based on available site area and target load criteria.
How do I choose a shallow attenuation tank size?
Start with the required effective storage and available footprint. Our matrix gives geometric capacity; the designer determines usable project capacity from the inlet, outlet and maximum water level.
Does 150 mm mean a 150 mm excavation?
No, it is the module height; any cover, pavement, bedding and protection layers add to the required depth.
Can the modules be stacked?
Yes; module height can be added by stacking, although we prefer a suitable single-height model where possible; structural integrity must be evaluated, including interconnects.
Can I use the tank under a car park?
Only where a project-specific design exists validating loading and cover. Do not use an ultimate compression number alone as a basis for loading.
Will a shallow tank solve flooding after a drain has been cleaned?
Not always; even with storage during heavy rainfall there may be flood effects from drainage system response, flow through the inlet, affected outlet or even restrictive infiltration. Check these flows before ordering greater storage capacity.
Can underground stormwater storage share space with basement parking?
This requires a project-based design showing structural compatibility together with a drainage analysis covering capacity, flow, structural conditions, site access and the total depth and space available for each system.
Is stormwater retention the same as detention?
Retention keeps water for infiltration or reuse; detention provides temporary storage of stormwater runoff before controlled release through the outlet. Indicate which application you need, as the protection wrap and outlet require different designs.
Does the module treat storm water?
The module is for water storage, not treatment. Treatment must be designed separately for the expected sediment and pollutants; underground stormwater storage does not automatically improve water quality.
What guidance should our designer review?
The applicable local requirements come first. CIRIA C737 and the BPF Pipes Group geocellular guidance discuss structural design issues; EPA groundwater guidance helps frame infiltration siting questions.
What determines the attenuation tank price?
Model, module quantity, connecting elements, supporting lining materials, packing and forwarding costs determine the quotation. When requesting a quotation, attach the project drawings or specifications, including required storage volume and project location details.
Do you provide installation and case studies?
We supply modules and specified technical services on offer; on-site construction must be carried out by your appointed contractor, so please forward any reference-project requirements along with your project details and our team will review these regarding their applicability and disclosure permissions.
How are sustainable drainage requirements checked?
Your designer needs to review the surface water runoff, allowable discharge, storage and overflow for the given site; the module is one component of the overall drainage systems used to manage the risk of flooding.
