WQ0000020_Request for Exemption to Permit Condition II 9.a._20090323

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NCDENR
North Carolina Department of Environment and Natural Resources
Beverly Eaves Perdue
Governor
John Toepfer, P.E.
Senior Environmental Technical Specialist
Environmental Services
Progress Energy Carolinas, Inc.
410 S. Wilmington Street, PEB 4A
Raleigh, NC 27601
Dear Mr. Toepfer:
Division of Water Quality
Coleen H. Sullins
Director
AQUIFER PROTECTION
March 17, 2009
RECEIVED/DENR/DWQ Dee Freeman
AQUIFERPROTFCTIONSECMN Secretary
MAR 23 2M
Subject: Progress Energy Request for Exemption to
Permit Condition II 9.a. — Setback from stream for ash
used as structural fill
Progress Energy Ash Distribution Program
Permit No. W00000020
Buncombe County
On December 29, 2008, the Division of Water Quality's, Asheville Office received Progress Energy's written
request for an exemption to Condition II (9)(a) of permit WQ0000020 that requires a 50 foot setback from any surface
water without prior approval from the Aquifer Protection Section when using ash for structural fill. Specifically, your
request is to use ash as structural fill over a culverted stream.
Based upon a review of your request along with supporting information, the Aquifer Protection Section is hereby
denying your request to reduce and effectively remove the stream setback requirement as specified in the subject permit
as well as Asheville Airport's 401 certification (DWQ #20071841)..Issues that were considered in this decision include but
were not limited to the following:
1. The subject permit allows ash to be used as structural fill beneath structures and paved surfaces where the
concentration of metals in that ash may exceed the ceiling concentrations and monthly average concentrations as
listed in the table of Condition 5. Based on your 2007 annual report, 14,025 tons of ash was distributed in
December of 2007 in which the arsenic concentrations of all three samples exceeded the ceiling and monthly
average concentration. Based on the 2008 annual report, five out of the 12 ash samples exceeded the ceiling
concentration. Please indicate on a site plan where ash exceeding these limits was used if used at the Asheville
Airport project. This will allow verification that this ash was used in a manner consistent with the permit
conditions. Additionally, the Division believes the stream setback requirements specified in the permit are
protective of surface water standards where ash with higher metal concentrations (i.e., above the ceiling
concentration or monthly average concentration) are allowed to be used as structural fill such as with this
project;
2. Approximately 300 ft. downgradient of the northern extent of the planned ash fill is a residential community. The
culverted stream, in which you are requesting reduced setbacks to, flows through this community and residents
appear to have easy access to the stream. Numerous homes in this community are on water supply wells, some
of which may be bored wells extracting groundwater from the more -vulnerable, shallow water table. The Division
is concerned with the presence of numerous downgradient (down-slope) receptors and therein, a higher potential
exposure risk. The information you have provided with your request does not address this major concern;
AQUIFER PROTECTION SECTION -Asheville Regional Office (ARO)
2090 U.S. 70 Highway, Swannanoa, INC 28778-8211
Phone: [phone] FAX: [phone]
Onee�'+
Customer Service: 1-877-623-6148
NOt url.aiolina.
Internet www.ncwater uali .o
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March 17, 2009
Page 2 of 3
3. Should the engineered controls such as the geosynthetic liner, impervious surfaces, culvert, etc. be compromised
and leaching occur, there appears to be few if any viable remedial or corrective measures to address a problem.
Given the volume of ash fill proposed, removal would not be an option. With limited corrective measure options
available and no contingency proposed, we can not support a setback exemption;
4. Condition I1.5 of your permit allows use of ash exceeding these ceiling and monthly average concentrations as
structural fill only if overlain by impervious surfaces (e.g., building footprint, paved area, etc.) and used at
individually permitted use sites. According to permit Condition IV.(1)(a), the Asheville Airport structural fill site is
considered individually -permitted by the Division. Permit Condition II.5.a. exemption is allowed at individually
permitted sites as stipulated in Condition IVA. which requires the establishment of a compliance and review
boundary around ash use site located outside the property boundary of the source -generating facility. Please
establish a compliance and review boundary in accordance with 15A NCAC 2L .0107(f) for the Asheville Airport
site including proposing location of monitoring wells, surface water sampling, etc. This monitoring is also being
required by the Division through permit Condition IV.(2)(a). Please provide documentation addressing this issue
within 90 days; and,
5. While the Asheville Airport's 401 certification references the "non -discharge requirements", Condition 12 of that
permit offers further clarification and restrictions by stating that "no waste ash fill over waters".
If Progress Energy believes the concerns outlined above can be addressed, you may resubmit your request with
additional supporting documentation to include, but not limited to, information to address these topics:
1. Progress Energy is to provide additional information on how the estimated 6% of ash fill that will not be overlain
by building footprint or paved surface on this project will be addressed if that ash exceeds the concentrations
listed in the table within Condition 5.;
2. In order to evaluate any setback reduction request, you would need to: (1) Demonstrate that use of ash as
structural fill for this project within 50 ft. of the stream will provide equal or better protection of the waters of the
State; (2) Identify potential receptors including water supply wells within 1000 ft, downgradient of the fill area;
and, (3) Identify any remedial or corrective measures or strategy that would be available if ash constituents are
detected in surface or groundwater at the site. Your demonstration should include a risk assessment or analysis
for all potential exposure pathways and predict potential environmental impact should engineered controls fail;
3. The Division is requesting that you evaluate the cost-effectiveness of:(1) overlaying the ash fill with a 1x10-6
cm/sec geosynthetic clay liner to further reduce potential infiltration and subsequent leaching of ash constituents,
and (2) using a composite liner such as a 60 mil HDPE membrane with either an underlying geosynthetic clay
liner with a maximum hydraulic conductivity of 5x10-9 cm/sec, or a 3 -foot compacted clay liner with a maximum
hydraulic conductivity of 1x10-7 cm/sec.;
4. From the available drawings, it is not clear the extent to which the underlain liner will 'wrap' on the sides of the
fill area as well as at the upgradient portion, nearest the junction box;
5. Please specify the life expectancy of the culvert material and include any contingency plan for repairing the
culvert should it be necessary in the future;
6. Verification that the Asheville Airport Authority has submitted an application for modification of the existing 401
permit, specifically, Condition 12 to allow ash to be used as fill over a culverted stream; and,
7. The subject permit allows you, the permit holder, to request an exemption to the 50 ft, stream setback.
Conditions that would likely be included with any permission to encroach on the 50 ft. setback would include
groundwater (monitoring well and possibly water supply well) and stream monitoring at a minimum. Any long-
term monitoring to verify the performance of the engineered controls to protect surface and groundwater would
be the responsibility of Progress Energy and therein, any required corrective measures pursuant to 15A NCAC 2L
.0106(d). One alternative arrangement would be for Asheville Airport to apply for a permit pursuant to TISA
NCAC 02T .1204 and seek setback reductions through a variance. Please provide documentation as to any access
AQUIFER PROTECTION SECTION — Asheville Regional Office (ARO)
2090 U.S. 70 Highway, Svannanoa, NC 28778-8211
Phone: [phone] FAX: [phone] One
Customer Service: 1-877-623-6748 NOl thCcir01111[1
Internet: www.nctvalemualitycra
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