Allied Asphalt Soakage Pit – AquaFort Stormwater System

Allied Asphalt, a key supplier of asphalt and bitumen in the Bay of Plenty, is in the process of upgrading its existing asphalt plant with a new, technically advanced production facility. This new site will also provide covered storage for raw materials. The site sits on a shallow water table, so to manage stormwater runoff, Allied Asphalt required a system that could be designed above the water table without compromising performance or durability. The solution also needed to withstand high traffc loadings from large vehicles and equipment.

DESIGN

Two soakage pits, approximately 88m³ and 25m³, were designed using the new AquaFort stormwater system. AquaFort modules were selected due to their superior load-bearing strength of 40t/sqm, compared to traditional plate systems at 27t/sqm. This upgraded strength allowed for a shallower excavation while still maintaining adequate cover material between the pit and the pavement surface. Additionally, the presence of services nearby required a system that could conform to irregular footprints.

AquaFort incorporates open channels within each module, allowing for greater maintenance when compared to the internal dividing plates used with traditional plate systems. DuraForce geotextile was used to fully wrap the AquaFort structure, although the system can also be installed directly onto a drainage aggregate base if required. The exibility in design made AquaFort particularly suitable for this complex site.

INSTALLATION

Speed of installation is one of the key features of AquaFort. AquaFort is manufactured in New Zealand, so it can be supplied without delay. The modules are lightweight, making them easy to transport and handle on site. For the 25m³ soakage pit, once site preparation was complete, the AquaFort system was assembled, wrapped and ready to be back lled in less than two hours.

The installation process involves placing the top and bottom AquaFort units, followed by connecting the side plates around the perimeter. These slot easily into position, with the unique clip system providing added rigidity to the structure. This design ensures a robust system capable of withstanding the anticipated tra c loads while also reducing installation time and labour costs.

AquaFort provided the designers with a versatile system that could conform to the complex nature of the site. For the client, AquaFort was a cost-effective solution with a rapid install time, thereby reducing delivery time on the new stormwater systems and minimising disruptions on site.

The AquaFort System provided the following benefits to the project:

• Increased speed of installation
• High loading capacity
• Accessible maintenance channels.