ECONOMICS AND VALUATION OF BIOAUGMENTATION - Bioaugmentation for Groundwater Remediation - page 315

biological degradation in a short time frame (i.e., before 6-12 months), significant volumes of
water must be pumped. For example, to achieve the same number of cells that would be injected
with 20 L of a commercially available culture, roughly 2,000-20,000 L of groundwater would
have to be extracted from the active area, transported to the new location, and injected into the
subsurface. These steps would need to be conducted while taking measures to maintain anoxic
conditions in the groundwater and prevent significant die-off of Dhc cells during the transfer
process. The process must be conducted in a way that completely eliminates contacting air at
any step in the process.
The cost of 20 L of culture may be in the range of $4,000. Recirculation of 2,000-20,000 L
of water would require installation and operation of a pump for some period of time, transfer
piping between the wells, or the rental and use of a tanker truck. The process also would require
labor and equipment to see that air is excluded from the operation. The cost for such an
operation easily could exceed the cost for a bioaugmentation culture with an equivalent number
of cells.
11.5 ESTIMATED COSTS FOR TEMPLATE SCENARIOS
The economic analysis of remedial options is a key activity in any remedy selection process.
It is typically employed in the feasibility study phase of remedy selection to aid in selecting the
optimal remedial option for a site, in concert with a number of other criteria. In an earlier
volume in this series (Stroo and Ward, 2010 ) on remedial technologies to treat dissolved phase
chlorinated aliphatic compounds in groundwater, an evaluation of costs for several remedial
technologies, including EISB was presented. The EISB costs presented in this earlier evaluation
assumed that bioaugmentation would not be conducted as part of the implementation of the
technology. In this chapter we look at the cost to include bioaugmentation as a component of
the EISB scenarios previously evaluated to provide three examples of what bioaugmentation
might cost.
This section presents a basic approach to generating cost information for EISB and for
the bioaugmentation component of EISB at three example sites where this approach could be
used to treat dissolved phase chlorinated aliphatic compounds in groundwater. Cost informa-
tion is broken down into design elements, capital expenditures, operation and maintenance
(O&M), and monitoring costs to help understand the primary cost drivers. The intent of this
section is not to provide definitive cost information for EISB and bioaugmentation technol-
ogy, since these are highly site-specific. Rather, the purpose is to give the design engineer a
general process to use in estimating costs when considering EISB and bioaugmentation at
specific sites.
11.5.1 Template Site Descriptions
The economic analysis presented here involves detailed costing for hypothetical template
sites and will be used in this section to cost the application of EISB with bioaugmentation for a
residual source area and two downgradient groundwater plumes containing TCE and its
daughter products. The template sites have been divided in this manner because source areas
and plumes are typically addressed independently in many feasibility studies.
The template residual source area (Case 1) consists of an area of 250 m 2 (2,690 ft 2 ). This
source area contains 200 kilograms (kg), or 440 pounds (lb) of TCE that is either adsorbed to or
present as a dispersed residual phase in the aquifer matrix. This situation is typical of many
small TCE source areas. The depth to groundwater is 1.5 m (4.9 ft), and it is 4.5 m (14.8 ft) to a