Element Environmental Solutions (E2S) was contracted by Souderton Area School District to provide storage tank removal and soil remediation services for the E. Merton Crouthamel Elementary School (EMC Elementary) located in Souderton, Pennsylvania. During construction activities of an expansion project for the elementary school, construction crews discovered a forgotten 285-gallon underground storage tank (UST). Evidence of obvious contamination associated with the 285-gallon gasoline tank was encountered during the removal. Noticeable petroleum odors were encountered and field screening with a photoionization detector (PID) confirmed the presence of volatile organic compounds in the air and in soils surrounding the UST.
E2S guided removal of the UST and excavation of the associated contaminated soils. Upon removal of the UST, dime to quarter sized holes were observed in the single-wall steel tank. E2S instructed the certified tank removal contractor to segregate the suspect clean and contaminated soils to ensure contaminated soils were not mixed with suspect clean soils. During excavation of contaminated soils associated with the gasoline tank, a concrete pad associated with another former heating oil tank was discovered. Petroleum odors were encountered upon unearthing of the concrete pad. Groundwater was also encountered as the depth of the excavation increased. Due to the proximity of the concrete pad and UST excavation to the existing school building, E2S personnel collected PID readings from within classrooms located closest to the excavation to ensure that indoor air quality was not impacted for students and teachers.
Following excavation of the contaminated soil, E2S followed the soil and groundwater sampling guidance outlined in the Pennsylvania Department of Environmental Protection’s Closure Requirements for Underground Storage Tank Systems technical guidance document to collect confirmatory samples. Five biased soil samples were collected in the area where contaminated soil was most likely to still be present and two groundwater samples were collected at the soil/groundwater interface. Residual contamination was identified in soils along the north-northeast side wall of the excavation and groundwater contamination was confirmed.
The results of the confirmatory sampling indicated that groundwater had been impacted by the release associated with historic USTs and that impacted soil was still present. At this time, E2S approached Souderton Area School District to discuss options for additional remediation. E2S informed the District of Pennsylvania’s voluntary cleanup program (Act 2), by which the District could voluntarily address contamination issues at the site and receive relief of environmental liability related to the impact from the former USTs. E2S initiated cleanup activities by filing a Notice of Intent to Remediate, which alerted PaDEP, the local municipality, and the public of the anticipated cleanup plan for EMC Elementary School.
Remediation efforts continued with additional excavation to remove the impacted soils. E2S implemented Systematic Random Sampling following the completion of excavation to collect soil samples from locations identified in the Systematic Random Sampling workbook. Review of the Systematic Random Sampling event confirmed that all impacted soils had been removed and the soil remediation was complete. Over 200 tons of impacted soil was removed from the site of the future elementary school expansion project and properly disposed of offsite.
The groundwater investigation was initiated with the installation of five groundwater monitoring wells across the elementary school property. One well was installed up-gradient of the source area, one well was installed at the source area, and three wells were installed down gradient of the source area as point of compliance wells. E2S collected groundwater samples from each well during quarterly sampling events to determine if extensive groundwater contamination was present or if the groundwater contamination discovered during the UST removal was localized and isolated. Analysis of the quarterly sampling events determined that extensive groundwater contamination did not occur, and that there was no remaining groundwater contamination concern.
The proximity of the USTs and associated excavation to the existing building prompted a soil gas investigation to ensure that all existing and future exposure pathways were eliminated. E2S worked with the construction contractor to ensure construction of the new school addition was not delayed by the potential for vapor intrusion concerns. E2S suggested installation of a vapor mitigation system within the footprint of the new addition. The vapor mitigation system eliminated any future concerns about students and staff coming in contact with vapors associated with the former USTs. E2S installed two sub-slab vapor sampling points through the floor of two rooms in the existing school building closest to the excavation. E2S contracted with a certified asbestos removal contractor during the installation of the sub slab sampling points, as 9”x9” floor tile, which often contains asbestos, was encountered in both areas. Following installation, the sub-slab sampling points were sampled over two consecutive quarters and analysis confirmed that sub-slab vapors were not impacted by the release associated with historic USTs.
The final step of this multi-year remediation project was to prepare and submit an Act 2 Remedial Investigation/Final Report to demonstrate that attainment of the residential Statewide health standard had been met for soil, groundwater, and sub-slab vapors. The report summarized all site characterization activities, laboratory analysis, and demonstration of attainment methodology. Souderton Area School District received cleanup approval and relief of environmental liability with the assistance from experiences and knowledgeable E2S Professional Geologists and environmental scientists.