Corrective Action Plan - Tennessee Valley Authority

Kingston Ash Release March 2009
Corrective Action Plan
During the ash cleanup period, observation wells will be installed in relevant aquifers at selected
locations in ash impacted areas to acquire data such as groundwater elevations, both prior to
and during cleanup. Data will be used to evaluate groundwater gradients and gradient changes
in response to changes in reservoir stage and to pumping of one or more wells. Observation
wells may be equipped with continuous pressure transducer data recorders. An additional
pressure transducer/recorder may also be placed in the reservoir and monitored in conjunction
with observational well systems.
4.2 OFFSITE PRIVATE WATER SUPPLY WELLS AND SPRINGS
Residential well water sampling is currently being conducted by TDEC. TDEC has sampled
residential well water within a 4-mile radius of the ash spill (Figure 4.1). On-going groundwater
monitoring to ensure protection of offsite private water-supply wells and springs during the
cleanup phase will be performed within the region proposed on Figure 4.3. The primary
groundwater contamination pathway of concern for offsite groundwater supplies is infiltration of
ash leachate below the ash laden land bordering the Emory River and its tributaries. Shallow
groundwater movement within each tributary watershed is expected to generally follow
topographic slope, i.e., with groundwater migrating down slope and ultimately discharging into
the stream. Any potential chemicals leaching from ash deposited along stream margins would
be expected to generally flow toward the stream. On this basis, the monitoring region shown on
Figure 4.3 is generally confined to the lower portions of the watersheds associated with ashimpacted
tributary streams on the west side of the Emory River. The region of monitoring
conservatively extends approximately 0.25 mile upslope of ash-impacted land and surface
water. This 0.25-mile buffer allows for uncertainties regarding localized groundwater flow
direction that can occur in fractured bedrock aquifers. Potential gradient reverse issues will be
evaluated as part of the overall groundwater monitoring program to be developed in conjunction
with the regulators.
On the east side of the Emory River, groundwater monitoring will be limited to river frontage
properties having wells located directly across the river from the ash-filled portion of the channel
(Figure 4.3). Although no ash-impacted land is present on or near these properties, monitoring
will be performed to assure there is no transport of ash-related chemicals from ash deposits in
the river channel to groundwater supplies due to hydraulic gradient reversals caused by overpumping
of wells or seasonal changes in reservoir stage.
Forty-seven (47) land parcels having inferred well or spring supplies are indicated within the
designated offsite groundwater monitoring region. Information regarding land parcels with
inferred private or individual water supplies on Figure 4.3 was provided by Roane County
Emergency Management, and is based on property records and records of residents served by
local public water systems. Examination of recent photo imagery indicates some of these
parcels are undeveloped and probably have no water supply. The status of existing well or
spring supplies within the monitoring region will be confirmed during the first monitoring event.
In addition, an attempt will be made during that event to obtain additional information regarding
each groundwater supply (e.g., well depth, screened interval, aquifer penetrated, water usage
rate, etc.).
Wells or springs located on properties impacted by ash deposits or within approximately 500
feet of ash deposits will be sampled quarterly during the first year. Other wells and springs in
the designated monitoring region will be sampled semiannually. The frequency of monitoring of
each well and spring will be re-evaluated annually based on monitoring results and proximity to
ash laden areas.
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