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HomeMy WebLinkAboutNCS000572_Dan River Add Info Response_20150922+f DUKE ENERGY. September 22, 2014 Rcopy 864 S. Edgewood Rd. Eden, NC 27288 RECEIVED SEP 2 2 2014 DENR-LAND QUALITy STORMWATER PERMITTING Mr. Bradley Bennett Via Email. bradley.bennett@ncdenrgov Supervisor, Stormwater Permitting Program North Carolina Department of Environment and Natural Resources Division of Energy, Mineral, and Land Resources 1612 Mail Service Center Raleigh, NC 27699-1612 Subject: Dan River Steam Station NPDES Stormwater Permit Application Duke Energy Response to Additional Information Request Dear Mr. Bennett, Duke Energy Carolinas, LLC (Duke Energy) presents the following information to the North Carolina Department of Environment and Natural Resources (NCDENR) — Division of Energy, Mineral, and Land Minerals in response to NCDENR's additional information request dated August 26, 2014. The request was submitted following Duke Energy's August 1, 2014 submittal of a National Pollutant Discharge Elimination System (NPDES) stormwater permit application for the Dan River Steam Station, located in Rockingham County, North Carolina. For ease of reference, NCDENR's excerpted queries appear in italics below, followed by Duke Energy's (DE) associated response. NCDENR: Analytical sampling results were provided for stormwater discharges from a July 15, 2014, rain event. The 10 sample locations included eight stormwater discharge points (SW001,003,004,005, 006, 007, 008, and 010), plus roof drainage from the power house building (apparently not a stormwater discharge location), plus a discharge point characterized as the former NPDES outfall 009(wasiewater outfall). Please clarify for us why the former wastewater outfall was submitted as part of the stormwater sampling effort. DE Response: The outfall in question was previously a dual stormwater/wastewater outfall. The NPDES outfall 009 was removed from the current NPDES permit when it became effective on March 1, 2013. The wastewater that was discharged through this outfall was non -contact cooling water from the combustion turbines that were located on site. These CTs were shutdown in 2012 and have been demolished. In terms of Storm water, 13.4 acres of facility potentially drains to this area. Due to discussions with the NCDENR and sampling results, we are proposing this outfall no longer be classified as a storm water outfall. YgO:)iB NCDENR: We note that the site map drawing identifies Future Outfall 009, but that no sampling data is presented for that outfall. We interpret the narrative description of the outfall to indicate that there is no discharge from SW009 presently. Please confirm our understanding of the narrative description, or provide sampling data for the outfall. Our understanding was that Duke would follow the same format as the Riverbend application in subsequent application submittals, including sample results from all stormwater outfalls. Please provide the missing sampling results for Outfall SW009, or provide a schedule for sampling it, or provide a clarification of the circumstances that indicate that sampling it is not appropriate at this time. DE Response: Proposed outfall SW009 is located in a groin area formed by the primary ash basin. This is the location of the 48" pipe, which has been grouted shut. The water that collects in this area is currently being pumped to the secondary ash basin. The water currently contains ash contact water. Until this area is addressed, a valid representative sample cannot be pulled. Looking at the sampling data portion of the application, there appears to a misprint. The sample data labeled drains to future Outfall SWO10 actually drains to future Outfall SW009. Future Outfall SWO10 is located at the inlet to the plugged 36" pipe. Water from this area is currently pumped to the primary ash basin. The water that collects in this area is storm water and potentially contact water from the 36" pipe. Until the inlet of the 36" pipe is permanently closed, a valid representative sample cannot be collected. In addition to the water that collects at the inlet of the 36" pipe, water from the drainage areas around the dry ash stacks will be conveyed through the future outfall, once the area around the dry ash stacks has been addressed in the ash basin closure plan. Currently this water gravity feeds to the secondary ash basin. Until this area is addressed, a valid representative sample cannot be collected This area has very little contributing drainage area, making obtaining a sample difficult during a storm event. Pumped stormwater flows (non -contact water) from the area above the 36 -inch pipe and from the Dredge area are proposed to be discharged at this location, but will not be discharged until approved by NCDENR DWR Stormwater. NCDENR: Please provide details (dates, locations on the .site, drainage areas impacted, etc.) about the present and past storage and/or releases of Polychlorinated biphenyl compounds (PCBs) on site. If there were any known releases, please discuss actions taken to remediate any areas affected. Include information about which drainage areas might have been impacts by PCBs. DE Response: Historically, this facility utilized mineral oil -filled electrical equipment that may have had low levels of PCBs. Other minor sources that may have contained PCBs were lighting ballasts, capacitors, etc. This use dates back to original start of operations at the site in 1949. All known PCB oil -filled equipment has been removed or reclassified. Stormwater drainage for in-service mineral oil -filled electrical equipment that may have had low levels of PCBs flowed to the site's ash ponds and discharged through the NPDES permitted wastewater outfalls. Stormwater drainage for in-service mineral oil -filled electrical equipment that may have had low levels of PCBs may also have drained to outfalls SW001, SW002 and SW004. The facility is completing minor PCB contaminated soil cleanups adjacent to past transformers that serviced the now retired and demolished combustion turbines at the site. Two transformers that contained oil in excess of 50 ppm PCB had minor soil/gravel staining that is being excavated and removed from the site. The soil around these transformers is being cleaned up to below 1 ppm with the excavated soils sent to Emelle, Alabama for disposal. This area drained to former NPDES outfall 009. NCDENR: The graphic presentation of the site sub drainage areas is visually confusing as submitted. Understanding the extent of the sub drainage areas feeding each stormwater discharge point is a key element in our review of the permit application. Please revise the site map drawing to more clearly delineate the sub drainage areas feeding each stormwater discharge point. The graphic presentation needs to be readily understandable so that our review can proceed. Drawing C-002 should require only minimal graphic changes to help us easily understand the site sub drainage areas. DE Response: Bolder colors for drainage areas and lighter/thinner line work for existing conditions (features, grades, etc.) have been added to the stormwater figures for clarity. Please see the attached updated drawings. NCDENR: In accordance with item V of the EPA Form 2F application, please confirm that Duke has observed all stormwater outfall conveyances on the site, and that Duke is reporting that only SW005 contains non-stormwater flows, and that Duke has reason to conclude that the observed additional flow is groundwater only. For future reference on other stormwater applications for this facility or for other Duke facilities, if any outfalls either were not observed, or included non- stormwater flows, please detail those conditions in EPA Form 2F. Also, if any other discharges have occurred during dry periods please indicate hou, those discharges are currently permitted, or will be permitted. DE Response: Duke Energy observed all stormwater conveyances on the site on July 3, 2014 and only SW005 contains non stormwater flow. We believe that the flow is groundwater because we had no precipitation for 2 weeks prior to application submittal, and there should be no other source of overland flow to that outfall Future Outfall 009 and 010 were not observed, but the potential is there for non stormwater flow due to ground water. NCDENR: We understand that the site is undergoing demolition of the coal fired plant. Please provide a schedule and narrative description of the demolition activities that could impact stormwater discharges. Our concern is that the conditions of the stormwater permit should anticipate changing site conditions during the demolition period. We want to check whether conditional provisions addressing demolition should be written into the permit and whether the provisions might be structured to lapse when the demolition is complete. DE Response: Please see the attached schedule. There are several projects that are either planned or underway at the Dan River Steam Station with regards to decommissioning. This includes decoupling of the CTCC raw water intake and wastewater discharges that were expected to be complete in July, 2014, but have been delayed; part of the project also includes the removal of power distribution equipment. Once the new raw water system has been commissioned and Power Delivery has removed switchgear/relays from the powerhouse, Duke expects the powerhouse to be completely de -energized and turned over to the abatement/demolition contractor for completion of the demolition work. This work is expected to continue from mid -2015 until mid -2016. Several other projects that may affect stormwater discharges from the site are in the planning/permitting stages including Coal yard restoration, diversion of storm water from the area currently draining through former NPDES Outfall 009/SW005, diversion of storm water from the area upland of the grouted 48" pipe to the Settling Pond, repair of the Settling Pond overflow pipe, closure of the 36" pipe under the basins, and storm drainage from the [Dredge] area between the two ash stacks as part of the ash basin closure scope. Coal yard restoration was originally expected to be completed following demolition. The current storm drainage system directs storm water from this area to the yard sump. Since the pipe failure in February, Duke has pursued temporary diversion of the sump discharge away from the ash basins and toward the Settling Pond by use of pumping and treatment packages where needed. This temporary diversion/treatment would be needed until the basins are removed and the storm water can be directed over their current footprints. An additional project includes the diversion of storm water from the area currently draining through former NPDES Outfa11009 (is this SW009 or NPDES Outfal1009?)/SW005 and storm water from the area upland of the grouted 48" pipe to the Settling Pond. Before the currently proposed diversion can be implemented, the area upland of the grouted 48" pipe must be addressed. Duke is pursuing permits to perform this remediation as it will impact an area with wetland features. Another project currently under development is a proposallspecification to repair the Settling Pond overflow pipe. This scope was previously expected to be implemented as part of site restoration in 2016, but is currently expected to be implemented between commissioning of the new raw water system and the return of the abatement/demolition contractor in 2Q15. In addition, we are expecting to address the closure of the recently plugged 36" pipe under the basins and the storm drainage from the area between the ash stacks as part of the ash basin closure scope. Our consultant has proposed the diversion of storm water from both of these areas to a new storm water outfall downstream of the secondary ash basin (Future SW Outfall 010). Before this canbe implemented, the area between the ash stacks must be addressed in the ash basin closure plan. The area currently drains to the secondary ash basin, which serves as treatment for the ash contact water. The implementation of this or another strategy to redirect storm water flows from these areas needs to be an integral part of the ash stackfbasin closure scope. NCDENR: Perhaps related to the demolition and the anticipatedfuture conditions, some outfalls are labeled on the site plan as.former and some as,future ". Please clarify for us the conditions that pertain at each outfall so characterized (Some limited explanation is already contained in the application for Future Outfall SW009 and future SW010.) Again, our concern is to access how to construct the permit conditions to account for discharges that may change over the term of the permit, or might ion the recent past have constituted a permitted outfall. DE Response: Please see the attached updated narrative for clarification of the "former" outfalls. NCDENR: Similarly we anticipate that the closure of the site's ash ponds may soon be underway, and that the activity may be begun and completed within the term of this stormwater permit. We would expect that some aspects of the ash pond closure activity may present the potential for stormwater pollution (for example activities such as transport of ash along on-site haul roads). In so far as is possible at this point in time, please provide information on the ash pond closure that could inform our drafting of the stormwater permit. Aspects such as the location of haul roads, time schedules, and site modifications necessary to accomplish the undertaking would help its to assess how the permit should address the stormwater risks from the activity. DE Response:: This work would start immediately upon confirming the destination for the ash, completing engineering for infrastructure to accommodate the closure strategy, and securing the necessary permits. Once those details are in place, we would expect to complete this work within 24 to 30 months. Any movement of ash will be dealt with in a manner consistent with current operations at existing Duke ash handling facilities. This may include, but is not limited to truck wash/wheel wash at ash loading or unloading areas,lined/sealed hauling containers/vehicles, dust control, haul route erosion control. These processes help to maintain the segregation between contact and non -contact stormwater, and help to mitigate generation of contact water by haul road areas. Duke Energy appreciates the opportunity to respond to NCDENR's request for additional information. Should you have any questions regarding this submittal, please contact Mr. Steve Cahoon at (919) 546-7457 or steve.cahoon@duke-energy.com. duke-energy.com. I certify, under penalty oflaw, that this document and all attachments were prepared ender my direction or supewision in accordance with a system designed to assure that qualified personnel properly gather and evahate the information submitted Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. l am aware that there are significant penalties for submitting false information, including the possibility ofJines and imprisonment far knowing violations. Sincerely, Duke Energy Carolinas, LLC Glenn E. Harris General Manager, Rockingham CT/ Dan River CC cc: Linda Hickok, Duke Energy Progress, Inc. Steve Cahoon, Duke Energy Progress, Inc. DEMLR Winston-Salem Regional Office DEMLR Stormwater Permitting Program Files DWR Central Files iITi MIM To From Date Subject Steve Cahoon File no Joshua Bell, PE cc Thursday 9/18/14 TMI I M�0 V 6226.14.0004.02 N/A Storm water Permitting and Pollution Prevention Support Drainage Area Narrative Dan River Steam Station AMEC was asked to aid Duke in evaluating and describing sources of storm water inflow and discharge at the Dan River Steam Station. AMEC has been working with Duke to evaluate these sources and develop options for diversion away from the existing ash basin. The following descriptions serve to further narrate the existing and future defined storm water outfalls for the Dan River Steam Station site and the existing precautionary measures in each drainage area. Service water Settling pond Overflow - Former NPDES 004 o Discharge Structure: 120 -inch diameter CMP o Location: Adjacent to Powerhouse Structure o Drainage area: 160+ acres o Area Description: This outfall receives waters from currently identified stormwater outfalls, in addition to stormwater from a larger upstream watershed from various other property owners. o Explanation: This area was in the past identified as a stormwater or NPDES outfall but lack of presence of wastewater and the location of identified outfalls upstream, plus status as a Water of the State renders this location no longer a stormwater outfall. • Combined Cycle SWO02 o Discharge Structure: o Location: o Drainage area: o Area Description: o Explanation: AMEC Environment 8 Infrastructure 2801 Yorkmont Road, Suite 100 Charlotte, North Carolina 28208 USA Tel (704) 357-8600 Fax (704) 357-8638 amec.com 36 -inch diameter RCP Southeast of Combined Cycle Station 18.02 acres This outfall conveys storm water flows generated from the north eastern corner of the Combined Cycle Station, which includes the northern 2/3 of the cooling tower, the two chiller buildings, the chiller PDC, and the 1000 gallon diesel and 500 gal kerosene storage tanks and their associated tanker unloading area. This area drains into the former SW 007, which is the grouted 48"pipe. This area is not discharging stormwater to the Dan River. Currently flows are pumped into the Secondary Ash Basin (NPDES treatment to NPDES-002) due to the presence of ash in the area above the grouted 48 -inch pipe inlet. Once the area has been restored, flows Storm Water Outfall Narratives 9/15/14 Dan River Steam Station AMEC Project No.: 6226140004 are proposed to be pumped to Future SW009, rendering sampling at the current Combined Cycle SW002 point unnecessary. Former NPDES Outfall 009/ former Dan River Steam Station SW 005 o Discharge Structure: Concrete ditch o Location: Southeast of Combined Cycle Station and adjacent to south end of Primary Ash Basin dike o Drainage area: 10.5 acres o Area Description: This outfall conveys storm water flows generated from an area south of the former combustion turbine area. The area also includes a portion of the existing Primary Ash Basin dike. o Explanation: This area is currently discharging stormwater along with some seepage, and stormwater runoff from most of the switch yard adjacent to the Steam Station. The switchyard runoff is processed through an oil trap tank and the water discharges through this outfall. The upgradient area is proposed to be pumped to future stormwater outfall SW009 once the outfall is approved. The area draining immediately adjacent to the Primary Ash Basin dike and the discharge from the oil trap tank is proposed to continue on as an NPDES outfall location. Storm Water Outfall SW001 o Discharge Structure: 48 -inch diameter RCP o Location: South of Combined Cycle Station o Drainage area: 17.42 acres o Area Description: This outfall conveys the majority of storm water flows generated from the Combined Cycle Station. Areas include the Substation, Admin building, Generator and Steam Turbine buildings, Clarifier, Clarifier Filters, Filter Press and 1/3 of the cooling tower. o Material Storage/Controls: Chemical and Fuel/Oil storage details can be found on the existing SWPPP document for the Combined Cycle Station and accompanying Figure 2. Secondary containment is provided for all chemical and fuel/oil storage. Additionally, protocols are in place to manage storm water accumulation in open air secondary containment areas. Valves in these areas remain in the closed position until criteria are met to release accumulated storm water into the drainage system. • Storm Water Outfall SW003 o Discharge Structure: 3 12 -inch diameter steel culverts o Location: West of the steam station powerhouse building o Drainage area: 1.02 acres Storm Water Outfall Narratives Dan River Steam Station 9/15/14 AMEC Project No.: 6226140004 Storm Water Outfall SW003, cont'd o Area Description: This outfall conveys flows from the laydown yard and storage area to the west of the steam station powerhouse building. All flow in the drainage area flows overland to a ditch leading to the outfall. Drainage area is gravel and grassed. o Material Storage/Controls: Spare equipment, parts, steel, iron, cable, and miscellaneous supplies are stored in the large, relatively flat gravel area. Some fabrication work may also be performed in the area associated with the steam station decommissioning effort. Equipment and supplies generally do not contain liquid. Storm Water Outfall SWO04 o Discharge Structure: 20 -inch diameter CMP culvert o Location: West of the steam station powerhouse building o Drainage area: 2.38 acres o Area Description: This outfall conveys flows from the laydown yard and storage area to the west of the steam station powerhouse building between the warehouse storage racks and the maintenance building. Flows in the storage area flow overland to a ditch leading to the outfall. Area also includes the oil storage building. Drainage area is gravel and grassed with some covered roofs. o Material Storage/Controls: Oil storage area drains to a 200 gallon sump. Drums of chemicals, cleaners, batteries, oils, and lubricants were stored here during plant operation. Spare equipment, parts, steel, iron, cable, and miscellaneous supplies are stored in the relatively flat gravel area. Some fabrication work may also be performed in the area associated with the steam station decommissioning effort. Equipment and supplies stored in the laydown area generally do not contain liquid. Storm Water Outfall SWO05 o Discharge Structure: 12 -inch diameter CMP culvert o Location: West of the steam station powerhouse o Drainage area: 0.07 acres o Area Description: This outfall conveys overland flows travel/working area on the west side of the steam station powerhouse. o Material Storage/Controls: No appreciable material storage is currently underway in this area. The area will be impacted in the future by temporary laydown and staging of materials during the decommissioning project. Storm Water Outfall Narratives Dan River Steam Station 9/15/14 AMEC Project No.: 6226140004 Storm Water Outfall SW006 o Discharge Structure: 8 -inch diameter CMP culvert o Location: West of the steam station powerhouse adjacent to the miscellaneous supplies are stored in the relatively flat powerhouse building o Drainage area: 0.33 acres o Area Description: This outfall conveys overland flows from the travel/working decommissioning effort. Equipment and supplies stored in area on the west side of the steam station powerhouse. o Material Storage/Controls: Storm Water Outfall SW008 No appreciable material storage is currently underway in o Discharge Structure: this area. The area will be impacted in the future by o Location: temporary laydown and staging of materials during the o Drainage area: decommissioning project. • Storm Water Outfall SW007 o Discharge Structure: Drainage feature/ditch outfall to service water settling pond o Location: North of Combined Cycle Station outfall o Drainage area: 21.12 acres o Area Description: This outfall conveys overland flows from the construction storage, parking and laydown area and a much larger wooded area on the west side of the combined cycle station. o Material Storage/Controls: No appreciable material storage is currently underway in this area. Spare equipment, parts, steel, iron, cable, and miscellaneous supplies are stored in the relatively flat gravel area. Some fabrication work or stockpiling may also be performed in the area associated with the steam station decommissioning effort. Equipment and supplies stored in the laydown area generally do not contain liquid. Storm Water Outfall SW008 o Discharge Structure: Drainage feature/ditch outfall to service water settling pond o Location: North of Combined Cycle Station outfall o Drainage area: 8.46 acres o Area Description: This outfall conveys overland flows from the construction storage, parking and laydown area and a much larger wooded area on the west side of the combined cycle station. o Material Storage/Controls: No appreciable material storage is currently underway in this area. Spare equipment, parts, steel, iron, cable, and miscellaneous supplies are stored in the relatively flat gravel area. Some fabrication work or stockpiling may also be performed in the area associated with the steam station decommissioning effort. Equipment and supplies stored in the laydown area generally do not contain liquid. 4 Storm Water Outfall Narratives Dan River Steam Station 9/15/14 AMEC Project No.: 6226140004 Future Storm Water Outfall SW009 o Discharge Structure: 6-8 inch diameter HDPE pipe from pump discharge o Location: Service Water Settling Pond south of SW002 o Drainage area: 45.0 acres o Area Description: This outfall will convey noncontact storm water flows from drainage areas DA -A, DA -B, and DA -C by pump to the service water settling pond. Areas will be discharged only after contact water generating sources have been removed from the areas. Currently these flows are pumped to the primary ash pond for treatment. o Material Storage/Controls: No appreciable material storage is planned for these areas. Future Storm Water Outfall SW010 o Discharge Structure: 6-8 inch diameter HDPE pipe from pump discharge o Location: Service Water Settling Pond south of SW002 o Drainage area: 77.8 acres o Area Description: This outfall will convey noncontact storm water flows from drainage areas DA -D, DA -E, and DA -F by pump to the north side of the secondary ash pond dike. Areas will be discharged only after contact water generating sources have been removed from the areas. Currently these flows are pumped or discharged by gravity to the secondary ash pond for treatment. This area includes the existing dry ash stacks. Construction in this area that would generate potential contact water will be managed to discharge to the secondary ash pond for treatment. o Material Storage/Controls: No appreciable material storage is planned for these areas. However, future construction in the area of the ash stacks may result in generation of contact water which will be discharged to the secondary ash basin, as is the current protocol.