Phase I and II ESA and Regulatory Human Health and Ecological Risk Assessment



Project Description:

ECOH was retained by the Client to develop an emergency response plan to assess and oil leachate which was observed seeping onto the school's playground and playing field.  As part of the emergency response program.  ECOH collected surface soil and surface water samples from the playground and playing field for analysis of various contaminants of concern, including PAHs, PHCs, VOCs, and metals.  The analytical results indicated that concentrations for select PAHs and metals were above the applicable MOECC site condition standards (SCS) at various locations throughout the site.  As such, immediate mitigating actions were implemented to protect the students and staff from exposure to the identified contaminants, and an Interim Human Health Risk Assessment was performed to address potential human health risks associated with the identified contamination.  Following the emergency response and the Interim Human Health Risk Assessment, ECOH conducted a Phase I ESA to determine the source of the identified contaminants and prepare a sampling and analysis plan for a Phase II ESA to further assess the site.  

The Phase II ESA work plan, included the advancement of 30 boreholes across the site (targeting the identified APECs) and the installation of 12 monitoring wells. The results of the Phase II ESA indicated that soil contamination was widespread throughout the site and remedial actions were required to address potential human health risks to the users of the site.  Following the completion of the Phase I ESA, and to assist the client in selecting a feasible remedial option for the site, ECOH developed a remedial options analysis.  As a result of the remedial options analysis performed by ECOH, and in consultation with the client, the MOECC and Toronto Public Health, it was concluded that a Regulatory Human Health and Ecological Risk Assessment (HHERA) was the preferred option to address the contamination at the site.  As such, ECOH and a sub-contractor, teamed together to undertake a “streamlined” HHERA and develop a Risk Management Plan (RMP) to address longer term mitigate controls at the subject site; all of which would be utilized to support the filing of a Record of Site Condition (RSC).

As part of the HHERA, ECOH developed a RMP, which included the application of an engineered cap barrier, a sub-drain system, future building restrictions, and planting restrictions.  The HHERA and RMP was subsequently approved by the MOECC and the RMP was incorporated into the Director’s Certificate of Property Use.  Lastly, ECOH developed an engineering specification and tender package for the client for the construction of the RMMs (i.e. cap barrier and sub-drain system), and the construction is slated to begin in the summer of 2015.