TBT Engineering News

Municipal Transit Site – Soil and Groundwater Quality Investigations


A municipal transit fuel storage system and parking lot had reached the end of its serviceable life, and as such, the fuel storage system required replacing and the parking lot required rehabilitation. Underground fuel storage tanks were replaced with above-ground tanks. In order to investigate any environmental concerns for reporting purposes, this required sampling of soils and monitoring of groundwater quality conditions, prior to and during site upgrades.

TBT Engineering’s Role

TBTE was retained by the client to conduct environmental subsurface investigations to establish baseline soil and groundwater quality conditions in the proposed area of the future aboveground fuel storage tank (AST) system; and, to determine if there were any potential issues of petroleum hydrocarbon contamination, related to fuel handling activities migrating towards adjacent properties.

The main aspects of TBTE’s field work program consisted of the following:

  • Arranging the location of all subsurface utilities;
  • Review of historic reports for evaluation and planning purposes;
  • Drilling boreholes to depths below water table and installing groundwater monitoring wells (GMW) for water quality testing;
  • Soil sampling for tank nest excavation;
  • Monitoring of volatile vapours on all soil samples collected;
  • Testing soil samples and groundwater sample for analysis of BTEX and Petroleum Hydrocarbon Fractions;
  • Decommissioning of damaged pre-existing GMWs and registration of newly installed GMW;
  • Analytical reporting on soil and groundwater results to applicable provincial standards;
  • Worked in conjunction with environmental contractor for completion of the work.


Advice was provided to the client at various stages throughout the project on logical steps forward and relevance of such future work.

Through these environmental subsurface investigations, the municipality was able to determine potential groundwater and soil contamination surrounding the pre-existing transit fuel storage system as well as for the location of the new fuel storage system. These results were reported to the relevant regulatory agency by TBTE.