Alta holds an As-Needed Environmental Assessment and Remediation Contract with Los Angeles County under which Alta has completed numerous projects related to site assessment, hazards wastes, and remediation. Most recently, the Men’s Central Jail site assessment projects were awarded to Alta under this contract. The County plans to demolish the existing facility and construct a new modern facility with an overall estimated project value of $2 billion.
Since 2014, Alta Environmental has been working at the 18-acre Men’s Central Jail facility and two satellite properties. Scopes of work included multiple ASTM-compliant Phase I and Phase II ESAs, a comprehensive Hazardous Building Materials Survey, and a Human Health Risk Assessment. The investigation was the first phase of a feasibility study and enabling project for the demolition, site prep, and construction of a new modern facility with an overall project value estimated to be close to $2 billion. Alta’s team continue to support the County by providing on-going services as the overall project progresses on this politically sensitive, highly visible project. Working in this environment is extremely challenging due to site restrictions, safety and security concerns, multiple levels of management and coordination for approvals, fluid schedules, and working with multiple stakeholders. Alta continues to meet the client needs for quality, stakeholder engagement, technical excellence, schedule and budget.
To date Alta has completed the following work:
Phase I ESAs
ASTM E1527-13 compliant Phase I ESAs were conducted for two off-site properties to assess feasibility for parking expansion projects and for the Men’s Central Jail complex as a whole to identify potential areas of concern which may impact future construction activities. Through the course of the Phase I ESAs, Alta identified multiple off-site and on-site potential concerns, including former industrial site uses, former and existing USTs, and off-site releases potentially impacting the subject property. Alta worked directly with the client to assess the significance of each identified potential concern and to develop work plans for further assessment.
Phase II ESA
Based on the findings of our Phase I ESA, Alta developed a Phase II ESA work plan in consultation with the client to investigate identified areas of potential concern. Field activities were conducted within the jail facility itself and within ancillary support areas.
Prior to any intrusive activities, geophysical surveys were conducted to locate detectable underground utilities and buried features of interest, and to clear the marked boring locations prior to future drilling and soil sampling activities. Several geophysical methods and equipment were employed, including an EM-61 high sensitivity metal detector, an EM-31 short terrain conductivity meter, a Ground Penetrating Radar unit coupled with a 500-MHz antenna, a shallow-focus conductivity meter (M-scope), and other electromagnetic utility-locating equipment. Detectable horizontal surface traces of piping, utilities, and anomalies were marked on the ground with paint in a color code established by the American Public Works Association.
Following the geophysical survey, investigation activities included the advancement of over 40 borings to facilitate soil, soil-vapor, and groundwater sampling. The initial five feet of every boring was manually drilled utilizing a hand-auger to mitigate potential conflicts with unidentified subsurface utilities or other obstructions. Beneath five feet, borings were advanced with direct-push drilling rigs to depths ranging from seven to 40 feet below grade. Collected soil and groundwater samples were variously analyzed for Title 22 metals, VOCs, and TPH. Following soil sampling, over 30 of the borings were converted to soil vapor sampling wells. Soil vapor samples were collected and analyzed in accordance with the DTSC/RWQCB 2013 Advisory for Active Soil Vapor Investigations. During the course of our Phase II ESAs, Alta identified multiple areas of potential concern for future site users and for construction workers.
Human Health Risk Assessment
Based on the findings of our Phase II ESA for the Men’s Central Jail complex, Alta developed a Human Health Risk Assessment (HHRA) to investigate the significance of identified potential environmental concerns. The HHRA assessed human exposure to chemical residue by utilizing standard equations and methods developed by the USEPA and the California Environmental Protection Agency for similar exposure conditions. Site-specific information regarding land use and receptors was used to quantify exposures to the media of concern. A fate and transport assessment was performed concurrent with the risk assessment. The fate and transport model was conducted to assess (1) whether VOCs detected in soil gas are likely to impact indoor air quality and (2) the degree and magnitude (if any) of such potential impacts.
Hazardous Building Materials Survey
Alta also conducted a comprehensive Hazardous Building Materials Survey of the Men’s Central Jail complex. The survey included visual assessment and identification of suspect materials, field screening utilizing an x-ray florescence (XRF) instrument, and the collection of samples for laboratory analysis. During our survey over 1,300 asbestos samples were collected, over 1,700 XRF readings were collected and over 500 paint chip samples were collected. Based on the findings of our survey, Alta developed general abatement plans for mitigating potential exposure to hazardous building materials during construction and by future site users.