REMEDIATING COMPLEX CONTAMINATED SITES: A FLORIDA CASE HISTORY - PowerPoint PPT Presentation

REMEDIATING COMPLEX CONTAMINATED SITES: A FLORIDA CASE HISTORY July 24, 2014 Environment & Health

Presentation Outline 2  Site History  Conceptual Site Model  Remediation Options  Questions I hope to provide you with a perspective on: the interdisciplinary nature of soil and groundwater remediation • how science and engineering contribute to the process, • Some of the non-technical issues that are involved. •

Site History 3  1888 to 1960: Operated as a Manufactured Gas Plant  1960 to Present: Property uses and ownership change.  1995 to present: Current property owners, the City and past MGP owners perform site investigations, risk assessment, and feasibility studies; oversight by USEPA and FDEP under the Superfund program.  2013: USEPA selects remedy for OU1 (top 60 feet); investigations continue on OU2 (190 to 450 feet below ground surface)  January 2016: Projected start date for OU1 remediation

Former MGP Operations Layout Based on Sanborn Fire Insurance Maps (1897-1973) and 1948 Plant Engineering Drawing

On-Site Parcels

Conceptual Site Model – Current Site Conditions

Developing a Conceptual Site Model Geology Site History Hydrogeology Common Sense Chemistry Microbiology Toxicology

Conceptual Site Models Evolve Over Time Review past and current site activities and properties Identify site and Identify existing Define the current T IME contaminant characteristics and potential distribution of that affect fate and receptors contaminants transport Screen various Screen potential risk remediation options management options Identify information gaps Collect more information and refine the Conceptual Site Model

Site Conceptual Model No direct exposure No imminent risk RGB 128/143/165

OU1 Soils and Surficial Aquifer Groundwater

Shallow Soil Contamination (2-10 feet bgs) 11

Shallow Groundwater Benzene Contamination 12 Groundwater movement is very slow, no surface water nearby.

Surficial Aquifer Zone 13

Conceptual Site Model – Generalized Cross-Section of Impacted Areas 14

Remedial Objectives for OU1  Contaminants: Benzene, naphthalene, ethylbenzene, polynuclear aromatic hydrocarbons (PAHs)  Objectives:  Prevent contact with contaminated soil and groundwater  Prevent migration of impacted groundwater  Remove or treat the contaminated soil  Use safe, implementable and proven technologies, be cost effective.

In situ Stabilization/Solidification 16

Biosparging – In situ Biodegradation 17

In Situ Chemical Oxidation 18

Selected Remedy (as refined in the ROD) LNAPL Impacted soil to 15 ft bgs LNAPL Impacted soil to 15 ft bgs

OU2 Upper Floridan Aquifer Groundwater

Conceptual Site Model – OU2 21

Upper Floridan Aquifer - Benzene 22