UST Removal/Excavation
former hesperia gas

The MDEQ (currently EGLE) retained ERG to conduct underground storage tank (UST) removal and petroleum impacted soil excavation activities at the former Hesperia Gas site, located at 442 West Michigan Avenue, Hesperia, Oceana County, Michigan. The work was performed under the 2017 Indefinite Scope Indefinite Delivery (ISID) Design-Build Services for Tank and Soil Removal contract between the MDEQ and ERG (2017 Design/Build ISID – Contract No. Y00687).

Per the Scope of Work provided to ERG by the MDEQ, the overall project goals were to: 1) Remove and properly close up to four regulated USTs and the associated piping and dispenser islands; 2) Excavate and dispose of up to 450 tons of petroleum impacted soils; and 3) Backfill and compact the excavation with clean sand, and restore the surface in accordance with the property owner’s direction.

A Triage Site Investigation was conducted at the site in July 2017. The geophysical survey of the UST area revealed multiple unidentifiable linear anomalies. Based on the results of the Triage Site Investigation, four unregistered USTs were identified at the site.

On September 25, 2018, ERG met at the site to uncover the tops of the USTs and collect a composite waste characterization sample from the USTs’ contents. During the uncovering, a 5th previously unknown UST was found. Once the tops of the five USTs were exposed, ERG collected liquid from the USTs to create a composite waste characteristic sample. The sample was submitted to a laboratory for analysis of VOCs, PNAs, and lead.

On November 5 and 6, 2018, ERG supervised the removal of six USTs (a 6th tank was discovered during the excavation process). Prior to removal, a total of 3,800 gallons of contact water was pumped from the tanks and disposed of at a licensed disposal facility. During the excavation process, ERG collected field screening samples to determine the limits of the excavation. All VOCs field readings were recorded at 0 ppm; therefore, the extent of the excavation did not extend past the UST basin. Due to the absence of VOCs in the soil, no soil was removed from the site.

At the request of the MDEQ Project Manager, ERG collected UST Site Assessment samples in accordance with the Michigan Underground Storage Tank Rules, 2012 AACS R 29.2101 et seq. The samples were submitted to the State of Michigan Environmental Laboratory of Lansing, Michigan for analysis of analysis of petroleum-related VOCs and PNAs. Because there was no evidence of a release, no verification of soil remediation samples were collected from the excavation sidewalls for analysis.

Following the completion of the excavation activities, the excavation area was backfilled with the overburden that was stockpiled during activities and 2 loads of clean sand. The sand was compacted in place with a vibratory compactor. Following compaction, 55 yd³ of gravel was placed on the compacted clean sand to create a gravel layer a minimum of 6-inches thick over the parking areas. Seeded top soil was placed in the yard area.

 SERVICES PROVIDED

UST System Removal/Exc.

Site Restoration