Page 29 - Trihydro Sustainability Report

Sustainable

Project Initiatives

Every year, the Sustainability Committee solicits feedback from Trihydro’s Business Unit Managers on
projects within their business units that use sustainable or “green” remediation practices. Examples of
green practices include:

1. Passive remedial systems: in-situ bioremediation, phytoremediation, engineered wetlands
2. Renewable energy-driven remedial systems: use of photovoltaic panels or wind turbines within
remediation technology

3. Waste-derived energy: conversion of combustible waste stream (e.g. land fill gas) into electricity
4. Efficiency optimization of existing remediation systems: upgrade existing equipment with more
efficient versions.
5. Minimization of waste use during site visits and/or reduction in frequency of routine monitoring

events: real-time data measurement, passive sampling, and remote data collection to minimize the
energy and waste resulting from site visits.

The following projects have been selected for inclusion in this report as examples of the green remediation
practices Trihydro uses in its client projects.

Use of in-situ bioremediation to treat chlorinated compounds at a RCRA site

NORTHEAST TEXAS

Trihydro operated an in-situ bioremediation (ISB) project at a RCRA site in northeast Texas, outside of
Dallas, to control groundwater impacted by tetrachloroethylene (PCE) and its degradation byproducts. The
ISB technology was pilot tested at the site in 2014, and full-scale implementation was achieved by 2015.
The full-scale design consisted of both source area treatment and biobarrier treatment, with each of these
areas being treated with an emulsified vegetable oil (EVO) bioremediation amendment delivered through
dedicated injection wells. The first EVO injection occurred in 2015. Trihydro monitored the success of the
ISB system through a semiannual groundwater sampling program. Performance data indicated that the
EVO bioremediation amendment was nearly consumed by spring of 2017, indicating a two-year reinjection
cycle, consistent with Trihydro’s EVO experience on other projects. During the time between injections, on-
site activities consisted only of semiannual groundwater monitoring. The only O&M costs during this two-
year period were analytical costs associated with ISB monitoring. This passive remedial system achieved
95% reduction in constituent concentrations in less than a year and attainment of protective concentration
levels in downgradient areas after two years.

HEALTHY ENVIRONMENT 25