The redevelopment and replacement of the existing fuel station at Waihola with a new upgraded fuel service station required specific engineering services across environmental, geotechnical, civil and fire departments. We also provided to our client full project management services to enable their project to be totally consistent and to offer them the best value for their capital investment of the new facilities.
Our environmental department oversaw and validated the removal and replacement of the Underground Petroleum Storage System (UPSS), providing on-site engineering and management services during demolition, removal processes, and providing soil testing and analysis for the purpose of off-site disposal guidance of surplus soils. We then provided a factual assessment report documenting the environmental investigation in accordance with the National Environmental Standard (NES) for assessing and managing contaminators in soil to protect human health.
A further consideration across the project was that the redevelopment program was to keep the old fuel supply station operational for as long as possible during the development and construction of the new fuel service station. This bought about further challenges that we overcame successfully.
"The redevelopment program was to keep the old fuel supply station operational for as long as possible during the development"
The previous fuel supply station and attached motor vehicle repair shop comprised of a 10,700L diesel aboveground storage tank (AST), an Underground Petroleum Storage System (UPSS) equipment including 5,000L, 10,000L and 20,000L petroleum underground storage tanks (USTs) with associated filling points, dispensing pumps and fuel lines. Prior to the demolition of the old fuel station and subsequent continued development of the new fuel station, the aboveground and underground petroleum storage system required removal.
We were engaged to provide on-site engineering services during the removal process; assessing contamination conditions around historical tanks and petroleum infrastructure through a combination of both in-situ soil testing and laboratory analysis.
Due to neighboring residential users, the nearby Lake Waihola and the risk of volatile gas accumulations associated with hydrocarbon-impacted soils, any contaminated soils required excavation and removal to an appropriately licensed waste disposal facility.
Significant hydrocarbon contamination was identified in isolated areas underlying parts of the UPPS system, which was confirmed through both initial on-site assessments and subsequent laboratory analysis. Contaminated soils were excavated and removed with remaining clean bedding material assessed, sampled and validated.
Following an extensive soil testing program the site was successfully deemed suitable for a commercial end-use, with contaminated materials removed from site and all remaining soils complying with relevant human health guideline criteria.
“We were engaged to provide on-site engineering services during the removal process; assessing contamination conditions around historical tanks and petroleum infrastructure”
Due to site constraints associated with overhead powerlines, the adjacent State Highway and the construction of the immediately adjacent fuel service station, space required to undertake the UPSS removal and soil remediation works was highly restricted.
This required efficient management and coordination of available space with clear communications between all contractors and site users.
With little to no space available to stockpile excavated soils, various on-site assessments from our environmental engineers regarding the contamination status of site soils were required to enable the immediate off-site disposal of contaminated materials. Through coordination with local landfill operators, soils were temporarily stockpiled off-site while awaiting laboratory test results to confirm appropriately licensed landfill facilities.
The presence of an environmental engineer on-site during the removal works undertaking in-situ soil testing, together with a pragmatic strategy and communication with local landfill operators, allowed excavated soils from the site to be assigned to different landfill facilities subsequently helping reduce disposal costs and timeframes for our client.
The project for NPD Waihola was completed on time and to budget with only forecasted minimal operational effects to the ongoing operation of the existing fuel station.