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Home My WebLink About20120285 Ver 1_Other Agency Comments_20070920� s STATE OF NORTH CAROLINA TURNPIKE AtTrHORITY MICHAEL F EASLEY 1578 MAIL SERVICE CENTER RALEIGH N C 27699 1578 GOVERNOR To From September 20 2007 NEPA/404 Merger Team Mr George Hoops P E Mr Steve Lund Ms Marella Buncick Mr Chris Militscher Ms Kristma Solberg, P E Ms Polly Lespinasse Ms Renee Gledhill Early Ms Marla Chambers Mr Hank Graham Mr Bob Cook Jennifer Harris, P E DAVID W JOYNER EXECUTIVE DIRECTOR Federal Highway Administration US Army Corps of Engineers US Fish and Wildlife Service US Environmental Protection Agency NC Department of Transportation NCDENR Division of Water Quality State Historic Preservation Office NC Wildlife Resources Commission Gaston Urban Area MPO Mecklenburg Union MPO Subject Gaston East West Connector (U 3321) Elimination of Detailed Study Corridor Segment KID As you recall resolution on NEPA /404 Merger Process Concurrence Point 2 (CP2) for the subject project was reached in September 2005 Sixteen Detailed Study Alternatives (DSAs) were identified for further study in the Draft Environmental Impact Statement Each DSA is comprised of several Detailed Study Corridor Segments These segments are shown in the attached map As project studies have progressed new information has become available regarding the viability of Detailed Study Corridor Segment KID The segment is located in the eastern portion of the project passing dust south of Duke Power s Allen Steam Station (see attached map) Based on information described in this memorandum the NCTA recommends that Segment KID be eliminated from further study Detailed Study Alternatives 6 24 65, and 78, which contain Segment KID, would therefore be eliminated from further study NORTH CAROLINA TURNPIKE AUTHORITY TELEPHONE 919 571 3000 FAX 919 571 3015 At the CP2 Merger meeting held September 20 2005 it was noted that segment combinations including KID had a straighter alignment and fewer stream impacts than comparable segment combinations but more residential relocations It was also noted that alternatives that included segment KID were dependent on the ability to construct a roadway over or through the Allen Steam Station s retired (dormant) fly ash basin An alignment within Corridor Segment KID could not avoid the fly ash basin To the north of Segment KID is the Steam Station s active coal storage and the plant itself To the south is the active fly ash basin i C % S tic �jkipy�) Retired Fly Ash Basin Also Just west of the fly ash basin is an active rail line used by the Steam Station and west of the rail line is the Catawba River These features are directly adjacent to each other and the rail line and river both must be bridged Constructing a roadway through the fly ash basin could have constructability issues and/or interfere with plant operations However no definitive data or information to make a determination was available at the time CP2 was resolved The Merger Team elected to keep Segment KID for further study, or until such time as data was available to revisit this decision This additional data is now available as described below In the first half of 2007, Duke Power conducted a site suitability study at the retired ash basin for the purpose of permitting a new landfill at the site Duke Power agreed to share their geotechnical data with NCTA At the request of the NCTA, the NCDOT Geotechmcal Engineering Unit reviewed the data to reach conclusions about the suitability of the site for roadway construction The provided their findings to NCTA in a memorandum dated June 1 2007 (attached) The fly ash basin in question is located south of the main plant and the Steam Station s active coal stockpile As described by Duke Power, it was in use in the early to mid 1970s, but is currently inactive and covered in vegetation An active fly ash basin is located farther south that is currently being used to store /dispose of ash waste generated by burning coal at the Steam Station The retired fly ash basin consists of three to four cells with a total size of about 2 000 feet by 1 650 feet (about 75 acres) Fly ash was 2 hydraulically placed with no engineering control relative to density /compaction The ash deposit in the basin has a maximum thickness of about 58 feet Upon review of the data provided by Duke Power, the NCDOT Geotechmcal Engineering Unit concluded that settlement /consolidation will be excessive and non uniform This would create an unacceptable condition in the form of waviness of the roadway surface and pavement failure The data further indicates considerable potential for embankment failure in the form of deep seated slope instability We conclude that roadway construction over the ash basin in its current state would not be feasible Bridging the entire fly ash basin was identified by NCDOT as the only practical alternative that eliminates the risk of potential large magnitudes of differential settlement Basically the bridge that would span the Catawba River and the rail line would need to be continued westward over the length of the entire fly ash basin (with piers that would need to be at least 60 feet long to clear the depth of the ash in the basin) With the fly ash basin as it exists today bridging this area would be feasible but would have substantial costs (see teleconference with NCDOT Structure Design Unit dated June 6 2007 attached) Additional information from Duke Power regarding their plans for the retired fly ash basin were received in a memorandum to the NCTA dated August 7 2007 (attached) The memorandum is summarized below The Steam Station is adding new pollution control equipment to comply with the North Carolina Clean Smokestacks Act (NC GS 143 215 107D) In conjunction with these improvements the Steam Station is in the process of designing permitting and constructing a storage area for coal combustion products over the retired fly ash basin The Steam Station states several alternatives and sites were evaluated for the future storage area but that the retired fly ash basin was the only viable site that provided the required capacity Design work is in progress in preparation for discussions with the NC Department of Environment and Natural Resources (NCDENR) Storage requirements will use the entire ash basin footprint and rise approximately 150 feet above the current elevation Construction is currently planned to start in late 2008 In conclusion bridging the retired fly ash basin in its current condition appeared to be a feasible although expensive option for constructing an alignment in Segment KID However with a new landfill over the fly ash basin rising about 150 feet in elevation, bridging is no longer a feasible option due to the elevation issues and interference with the Steam Station s operations Therefore, NCTA recommends that Detailed Study Alternatives that include Segment KID (DSAs 6, 24, 65, and 78) be eliminated from further study The reasons for elimination would be documented in Chapter 2 of the DEIS 3 If you need additional information in order for your agency to make a decision regarding the elimination of DSAs 5 24, 65 and 78 from further study please call or email me (919 571 3004) or iennifei harrisLivncturnpike org) Attachments • Memorandum from Duke Power dated August 7, 2007 • Memorandum from NCDOT Geotechmcal Unit dated June 1, 2007 • Record of teleconference with NCDOT Structures Design Unit dated June 2007 • Memorandum from NCDOT Geotechmcal Unit dated September 15, 2005 • Map of the Gaston East West Connector Detailed Study Alternatives r 11 i I ' I I Duke 526 Church Street i Energy® Charlotte NC 28202 Marling Address EC10C /P0 Box 1006 Charlotte NC 28202 August 7 2007 Steve D DeWitt P E Chief Engineer North Carolina Turnpike Authority 1578 Mail Service Center Raleigh NC 27699 -1578 Dear Mr DeWitt Subject North Carolina Turnpike Authority TIP U -3321 Gaston East -West Connector Allen Steam Station Future Operations This letter is in response to your July 6 2007 letter to Mr Immel requesting information on future operations of the inactive ash basin Upon review of your map of the proposed alternative segments it appears that Segment K1 D does cross over the retired ash basin This retired ash basin is bounded by the coal stockpile to the north the Catawba River to the east and the active ash basin to the south The Allen station will be adding new pollution control equipment flue gas desulfurization — or scrubbers to comply with the North Carolina Clean Smokestacks Act requirements See N C Gen Stat § 143 -215 107D In conjunction with this modernization the Alien station is in the process of designing permitting and constructing a storage area for Coal Combustion Products over the retired ash basin Initial site investigations have been performed and design work is in progress in preparation for discussions with NCDENR To obtain the required capacity we are planning to use the entire retired ash basin footprint and rise approximately 150 feet above the current elevation The storage area will most likely be constructed with a double synthetic liner system with a witness zone between the liners Construction is currently planned to start in late 2008 The project team had evaluated several alternatives and sites for the future storage area however this was the only viable site that provided the required capacity I hope I have addressed you request, however if you have any additional questions please feel free to contact me at (704) 382 -8691 or e-mail tamanes @duke- energy com Sincerely Theodore A Manes Project Manager www duke energy corn cc Steve Immel Plant Alien Station Manager Tim Gause Gaston District Manager MICHAEL F EASLEY GOVERNOR �Jy µSTATE'O N � STATE OF NORTH CAROLINA DEPARTMENT OF TRANSPORTATION MEMORANDUM TO June 2007 Jeff Dayton N C Turnpike Authority FROM Njoroge Wamalna State Geotechnical Engineer NCDOT — Geotechnical Engineering Unit LYNDo TIPPETT SECRETARY STATE PROJECT U 3321 COUNTY Gaston DESCRIPTION New Route from 185 West of Gastonia to NC 160 In Mecklenburg County SUBJECT Geotechnical Report — Segment KID over the Retired Fly Ash Basin at Allen Steam Station Duke Energy has conducted a site suitability study at the retired ash basin for the purpose of permitting a new landfill at the site They have provided data from their subsurface investigation I have reviewed the available data in order to provide comments to the Transit Authority regarding the feasibility of the site for roadway construction The site in question is on the property of Duke Energy at the Allen Steam Station near Belmont N C The site is a retired ash basin It was active in the early to mid 1970 s It consists of three to four cells used for storage /disposal of ash waste generated by burning of coal for production of electricity The ash was hydraulically placed with no engineering control relative to density /compaction The area is now vegetated It is bounded to the north east and south by dikes The steam station s active coal pile is dust north of the site an active ash basin is to the south and the Catawba Riverjust to the east The size of the site is roughly 2000 feet by 1650 feet MAILING ADDRESS NC DEPARTMENT OF TRANSPORTATION GEOTECHNICAL ENGINEERING UNIT 1589 MAIL SERVICE CENTER RALEIGH NC 27699 1589 TELEPHONE 919 250 4088 FAX 919 250 4237 WEBSITE WWW DOH DOT STATE NC US LOCATION CENTURY CENTER COMPLEX ENTRANCE B 2 1020 BIRCH RIDGE DRIVE RALEIGH NC { 2 I �t Summary of test data for the ash material The ash deposit has a maximum thickness of about fifty eight feet Shear Strength parameters for the ash (Triaxial CU normal stress) C cp Lb /ft2 Deg 210 18 8 0 156 950 11 1 380 195 One dimensional consolidation Cc ranged from 0 09 to 0 22 Wet unit weight ranged from 89 8 to 94 0 lb /ft3 Standard Penetration Test values in the ash were commonly around 2 blows per foot and did not tend to show any increase with depth Groundwater is present across the site at depths of one to ten feet below the existing ground surface Interpretation of the test data The data indicates that settlement /consolidation will be excessive and non uniform This would create an unacceptable condition in the form of waviness of the roadway surface and pavement failure The data further indicates considerable potential for embankment failure in the form of deep seated slope instability We conclude that roadway construction over the ash basin in its current state would not be feasible Potential treatment options include Bridge the entire fly ash basin Bridging the fly ash basin is the only practical alternate that eliminates the risk of potential large magnitudes of differential settlement that may occur There is risk in considering other treatment options of the fly ash to support an embankment and roadway Other treatment options are discussed below however for feasibility study there is risk in considering them as they may or may not completely perform as expected 3 Excavation and replacement of the ash material This is largely impractical due to the large volumes involved and the high groundwater table Dynamic compaction Minimally effective due to the depth of the ash material high groundwater and fine grained nature of the fly ash material Pile supported embankment This is a potentially feasible solution very similar to bridging the fly ash basin The number of piles would be substantial and more than for a bridge Piles are typically on 5 foot centers Many of the piles would be 50 to 60 in length The footprint of the embankment is substantially larger than that of a bridge Pile supported embankments are typically cost effective if the unsuitable soil is less than 30 feet in depth A study of the corrosive potential of the ash would be required Soil mixing or jet grouting This potentially could work but would be more expensive than bridging and the entire footprint of the embankment would require treatment Prepared by Clint Little NCDOT Regional Geological Engineer CONFERENCE CALL NOTES GASTON EAST -WEST CONNECTOR Gaston and Mecklenburg Counties Date June 6 2007 Time Afternoon Place Via Telephone Subject Construction Options Over the Allen Steam Station Fly Ash Basin Attendees Tom Koch Jill Gurak Notes NCDOT Structures Unit PBS &J The purpose of the meeting was to request input from Mr Koch regarding the recent results of the geotechnical study on the Allen Steam Station Fly Ash Basin The geotechnical study was performed by the Allen Steam Station They agreed to share the results with the NC Turnpike Authority Mr Clint Little, from NCDOT s Geotechnical Unit reviewed the results of the geotechnical study for NCTA A memorandum dated June 1 2007 from Njoroge Wamaima ( NCDOT State Goetechnical Engineer) prepared by Mr Little provides a summary of Mr Little s review of the geotechnical data This memorandum is attached Mr Little states that roadway construction over the ash basin in its current state would not be feasible Bridging the fly ash basin is the only practical alternate that eliminates the risk of potential large magnitudes of differential settlement that may occur Pile supported embankments are also a potentially feasible solution very similar to bridging the fly ash basin Pile supported embankments are typically cost effective if the unsuitable soil is less than 30 feet in depth " Based on Mr Little s comments Mr Jeff Dayton of HNTB thought it may be beneficial to discuss these findings with a structural engineer Mr Dayton and Mr Koch could not get in contact before Mr Dayton left for vacation so Mr Dayton asked Mr Koch to contact me Ms Gurak provided Mr Koch some background on the Gaston East West Connector project and the Detailed Study Alternative that passes over the Allen Steam Station s fly ash basin (currently inactive) Currently, preliminary designs are being prepared in support of the Draft Environmental Impact Statement Just to the west of the fly ash basin is an active rail line used by the steam station West of the rail line is the Catawba River These three features are directly adjacent to each other and the rail line and river both must be bridged Meeting Notes June 6 2007 Mr Koch stated that pile supported embankments would not be feasible for a mayor roadway in this location due to the long length of embankment needed to traverse the fly ash basin and the depth of ash (up to 58 feet in depth) A bridge could be feasible but piers would need to be at least 60 feet long (vertically) to clear the depth of the ash basin This type of bridge for the subject project would add substantial cost to the alternative over the fly ash basin There is a bridge on the US 17 Windsor Bypass that is similar in height and length although it is up in the air rather than sunk into the ground That bridge is 1 700 feet long with cored slabs each 50 feet long Mr Koch stated he can provide a basic cost for the bridge during the cost estimating stage of the preliminary engineering designs It is not possible at this time to determine whether the alternatives over the fly ash basin (including the necessary bridging) would be significantly more expensive than the other detailed study alternatives Once the preliminary designs are completed construction and right of way costs can be estimated and compared for each detailed study alternative 4 STATE OF NORTH CAROLINA DEPARTMENT OF TRANSPORTATION MICHAEL F EASLEY LYNDO TIPPETT GOVERNOR September 15 2005 SECRETARY STATE PROJECT 34922 1 1 (U 3321) F A PROJECT STP 1213 (6) COUNTY Gaston Mecklenburg DESCRIPTION Gaston County East West Connector from I 85 West of Gastonia to NC 160 in Mecklenburg County MEMORANDUM TO Mr Gregory J Thorpe PhD Director Project Development and Environmental Analysis Branch FROM John L P►hpchuk LG PE Western Regional Geotechn►cal Manager Geotteeecchn►cal Engineering Unit Gregory A Smith LG PE GeoEnvlronmental Supervisor Geotechn►cal Engineering Unit SUBJECT Allen Steam Plant Fly Ash Basins The GeoEnvlronmental Section performed a non intrusive investigation of two fly ash basins immediately south of Duke Power s Allen Steam Plant property near Belmont Our findings are to partially assist in determining the suitability of Segments KI B KiC KID for additional study The northern basin is inactive and vegetated while the southern basin currently receives approximately 12 000 gallons of fly ash slurry per day The above segment alignments cross a portion of the northern basin Fly ash was placed in the basin via water slurry the solid material settled out and the water was discharged from the basin into the Catawba River Typical of such operations Duke Power practiced no engineering control over consolidation of the ash The resulting material has low strength and is generally unsuitable as a structural foundation without modifications Roadway construction across the basin must therefore include considerable in situ modifications to the ash s physical properties necessary for improved constructab►l►ty or its excavation and replacement with suitable embankment material MAILING ADDRESS NC DEPARTMENT OF TRANSPORTATION GEOTECHNICAL ENGINEERING UNIT GEOENVIRONMENTAL SECTION 1589 MAIL SERVICE CENTER RALEIGH NC 27699 1589 TELEPHONE 919 250 4088 FAX 919 250 4237 WEBSITE WWW DOH DOT STATE NC US LOCATION CENTURY CENTER COMPLEX BUILDING B 1020 BIRCH RIDGE DRIVE RALEIGH NC 27610 Mr Gregory J Thorpe PhD September 15 2005 Page 2 Fly ash usually exhibits physical properties suitable for embankment material when it has been properly dried and compacted Environmental impacts regarding contaminant concentrations within fly ash generally are not a major concern as with bottom ash but appropriate chemical analyses must be performed prior to acceptance of the material A geotechnical /geoenvironmental field investigation can be scheduled if more detailed information is needed to make a final decision regarding the status of the segments in question Please contact Greg Smith GeoEnvironmental Supervisor at (919) 250 4088 for additional geoenv iron mental information or John Pilipchuk Western Regional Geotechnical Manager at (704) 455 8902 for additional geotechnical information 0 w z oZ W�o zt�U 0 P U =) N O m w z W F- -j FwU Now LLI > a z Zia Z z O 0, z a i O C7 U) a c� i p �A77i ,� Cif !'p►� Mr SWIL low - -4 jai �, � ALA.' • ��I� tF �y t ,ors► � .� _I • unoo • N W F Q 2 2 W cn F J Q D r 0 W J a LU w C W O z W 0 U cc a b E a$ as k P iq �it S Gl� a II1II II10 0 c