Land Utilisation – Vermont Grove Drainage Basin

Ground Civil is proud to announce the successful completion of a stormwater drainage project for our client, Vermont Grove Pty Ltd. The project involved the design and construction supervision of a drainage basin on Lot 8 of Vermont Grove, a residential development in Madeley, Western Australia. The drainage basin is intended to manage the stormwater runoff from the site and prevent flooding and erosion.

Project Background

The site of Vermont Grove is located within the City of Wanneroo, which has a high rainfall intensity and a good infiltration rate. The site is also subject to the requirements of the City of Wanneroo’s Engineering Design Specification D09 Stormwater Drainage (Design), which specifies the minimum standards for stormwater drainage systems.

The initial design of the drainage basin done by the previous consultant on Lot 8 was based on the assumption that the site had no infiltration capacity, meaning that all the runoff from the site would be collected and stored in two basins. However, preliminary modeling using SWMM software suggested that the initial basin sizing was quite conservative and did not consider the site infiltration rate. This meant that the basin was larger and deeper than necessary, which would result in higher construction costs and land use impacts. After a re-design GC managed to delete one basin and free that part of land to be used as a residential lot.

Project Solution

Ground Civil obtained permission from the City of Wanneroo to conduct a revised basin size and volume calculation based on both the existing capacity and the infiltration rate of the site. To determine the infiltration rate, Ground Civil engaged a geotechnical company to conduct soil testing and analysis. The results showed that the site had a moderate infiltration rate.

Based on the revised calculation, Ground Civil designed a stormwater pipe connecting part of the existing development to another existing basin that would still meet the design criteria and performance objectives of the City of Wanneroo. The new 300mm stormwater RC pipe connects the existing drainage system to the existing sump on the end of Old Trafford Ave in Madeley. 

Project Benefits

The project delivered the following benefits for our client and the community:

• Reduced construction costs and land use impacts by optimising the basin size and volume
• Improved stormwater management by incorporating infiltration and detention functions
• Enhanced environmental quality by reducing unnecessary basin size.
• Utilising one more lot as a residential block.

Ground Civil would like to thank Vermont Grove Pty Ltd and the City of Wanneroo for their cooperation and support throughout the project. We are pleased to have delivered a high-quality and cost-effective solution that meets the needs and expectations of our client and the community.