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Home My WebLink AboutNC0073181_Correspondence_20040518o�o� WATF�pG � r Mr. Daniel C. Shields, P.E. Principal Engineer May 18, 2004 Mactec Engineering and Consulting, Inc. 5710 Oleander Drive, Suite 110 Wilmington, North Carolina 28403 Michael F. Easley, Governor State of North Carolina William G. Ross, Jr., Secretary Department of Environment and Natural Resources Alan W. Klimek, P.E., Director Division of Water Quality Subject: Alternate Discharge for Groundwater Remediation System ExxonMobil South Wilmington Terminal NPDES Permit NCO07JI81 New Hanover County Dear Mr. Shields: In order to obtain a NPDES permit for a groundwater temediation system that operates at the 25-50 gpm rate, you would need to complete the Engineering Alternative Analysis, the short from C-GW, and submit these documents along with the appropriate fee and chemical characteristics of the treated groundwater to the NPDES Unit. Analytical data shall include chemical constituents of concern, TSS, BOD and data on any substances that are being added to the treatment system. Please be advised that a permit for treated groundwater will likely contain a requirement for chronic toxicity testing due to the complex nature of the waste stream. We would recommend that you conduct a chronic toxicity test with treated groundwater to determine if you could meet this requirement. If you have any questions concerning this permit, please contact Sergei Chcrnikov at telephone number (919) 733-5083, extension 594. Sincerely, �y ave Goodrich, Supervisor, NPDES Unit cc: Central Files Wilmington Regional Office/Water Quality Section NPDES Unit North Carolina Division of Water Quality (919) 733-7015 1617 Mail Service Center FAX (919) 733-0719 Raleigh, North Carolina 27699-1617 On the Internet at http://h2o.enr.state.nc.us/ ehit /UPUEs Uni f cCaawJ�s sm� 0 Q 000 8 r Z1 . LETTER OF TRANSMITTAL To: From: MACTEC Engineering and Consulting, Inc. Project/Job No.: Date: , JJ � it y!s h-q.kc- 4 •-` 5710 Oleander Drive Suite 110 Project: G.s��v3a� dt Wilmington, NC 28403 r Description: Ale Attn Attu: COPIES DOC. NO. DATE DESCRIPTION p THESE ARE TRANSMITTED AS CHECKED BELOW: —0 r 0 For Approval 0 Approved as Submitted 0 Resubmit Copies for Approval ;; ❑ For Your Use 0 Approved as Noted ❑ Submit Copies for Distributiomn 2 0 As Requested 0 Returned for Corrections 0 Return Corrected Prints z ❑ For Review and Comment Other ❑ Prints Rehuned After Loan to us ❑For Bids Due: REMARKS: Copies To: Signed: IF ENCLOSURES RECEIVED ARE NOT AS LISTED ABOVE, PLEASE NOTIFY US AT O C43 �U July 3, 2003 Division of Water Quality NPDES Unit 1617 Mail Service Center Raleigh, North Carolina 27699-1617 Subject: Information Request Regulatory Guidance Alternate Discharge for Groundwater Remediation System Q W Through Existing NPDES Discharge Point (NC0073181) c` ExxonMobil South Wilmington Terminal Wilmington, North Carolina CO MACTEC Project No 6550030027v .: rn x m :a Dear Sirs: ul Yv ExxonMobil is interested in exploring an alternate discharge for the treated effluent from an on - site groundwater remediation system at their South Wilmington Terminal (SWT) located at 3340 River Road in Wilmington, North Carolina. The purpose of this letter is to request regulatory guidance on the permissibility of changing this remediation system discharge from a non - discharge (ND) to a discharge (NPDES) as a second outfall (002) added to the existing NPDES permit. The SWT currently discharges stormwater on an infrequent basis with their existing NPDES Permit (NC0073181) through an on -site pond. The pond also serves as a retention facility as per the SWT's Spill Prevention Control and Countermeasures (SPCC) plan and has a freeboard requirement. The freeboard requirement and the constant discharge from the remediation system necessitate the second discharge point request. The remediation system currently collects groundwater impacted with primarily para-xylene, treats the groundwater using air stripping and carbon adsorption and discharges to an on -site MACTEC Engineering and Consulting, Inc. 5710 OLEANDER DRIVE, SUITE 110 • WILMINGTON, NC 28403 910-452-1185 • Fax: 910-791-1338 ExxonMobil South Wilmington Terminal 71312003 MACTECProject No. 6550030027 Final infiltration gallery located on the south portion of the terminal property. The discharge to the infiltration gallery is permitted by a North Carolina Non -Discharge Permit (Permit No. WQ0008129) and is monitored monthly for the chemical constituents of concern (benzene, toluene, ethyl benzene, xylenes, MTBE, and Isopropyl ether). MACTEC Engineering and Consulting, Inc (MACTEC) retains records of the sampling results and they are reported to the state monthly. The sampling point for the effluent water pumped to the infiltration gallery is after the carbon cells located in the treatment building. The analytical results for this point indicate the effluent meets the North Carolina Ground -Water Quality Standards. for Class GA groundwaters since the remediation system was activated in 1995. In the approximately nine years since the remediation system was completed, the infiltration gallery's performance has diminished. The remediation system effluent has always tested non - detect for the organics but contains elemental iron, iron bacteria, and possibly traces of an iron sequestering chemical admixture (Shan -No -Corr ®) used to prevent iron deposition on the air strippers. Apparently these compounds are mechanically blocking the infiltration gallery gravel bed and native receiver soils and have made them less permeable. The Shan -No -Corr ® is a bimetallic zinc metaphosphate sequestering agent and is added to the system influent at an approximate feed rate of 1.0 ppm. The effluent has not been tested for this compound. The average flow for the system is between 25 and 50 gallons per minute (gpm). The ND Permit flow limit is 100 gpm. Several attempts have been made to "unplug" the infiltration gallery using pressure washers and other cleaning apparatus with no success. The groundwater remediation system discharge is limited by the infiltration rate in the gallery. A map is attached that contains the location of the existing permitted NPDES outfall and one that shows the general site layout with the location of the infiltration gallery. In a telephone conversation with Joe Corporon on June 27, 2003 he stated that ExxonMobil would need to complete the Engineering Alternative Analysis (EAA) for the proposed project change. Please inform us of any other application forms that would need to be completed and also determine if the short form C-GW can be used since this proposed discharge is from a groundwater remediation system. h:IclienislerxonitermlwilmlinfiltraIpondcl.doc 2 a ExxonMobil South Wilmington Terminal MACTEC Project No. 6550030027 71312003 Final If you have any questions or need additional information, please contact me. Thank you for your cooperation. Sincerely, MACTEC ENGINEERING AND CONSULTING, INC. 1 r 10'� 'stina A. Theodorson Project Scientist BY-4- WmIJITTHE-RMISSION b---�L i k Daniel C. Shields, P.E. Principal Engineer h: ;clien tsle — on (term lwilm l in filtra 1poncid doc 3 (i� �. (S to j ` l ' l Au rityoil 0 / III111 •• y f i - e--.. ••�.� ' ��0— i, •I 0 RUTCEOGE a 13 r T ii • ! • • I �� _ -1 I •� �) �• • fankvr�� OUTFALL 001 t Ta i,, } ,o ExxonMobil Chemical Company: ` Facility Location State Grid/Ouad: Wilmington Latitude: 340 10' 43" N Mt to scale K 27 NW Longitude: 790 57' 16' W Receivine Stream: Cape Fear River Drainage Basin: Cape Fear NPDES Permit No- NCO073181 Stream Class: Sc Sub -Basin: 03-06-17 North New Hanover County GRAPHIC SCALE - IN FEET 150 75 0 150 300 Mw-28 • " W-1 OEMY FAL9 /�� Air. •_--.. __�..!__...__..__'�... __- _ vim'.✓'� �=�- r'- ) rMW,22 AMat 14 1 W47 I 1 11 �T��iv� `< 1 �' J P�Ca7 i �juN' i M W-1 I fw.i i4 to " i 11 i ern P_X-DEEP MW8 MW-2' MW5 • r..15 I aI 1M 'a r CLL Mw•8 ___--_-__. PIVEP�nOAD=�i ��,_0' _MR /-�Y�)��:a---�•..��: o ;X4- '" fl f . dwt,• m wa — C _ RIVER RdAD to I f� Li M 27 LEGEND: �� '� 001 Px-5 • RC-9 GROUND WATER MONITORING WELLS • STORMWATER r MW-24 ` POND �f @RW ,_ RECOVERY WELL a- nn ergo �, 0#�.�•-'tea..-_�---' /..1 � r en a o' ii[r3 C R64 • iRC-5 = f MW40 r....,ur4 1ij - --MW21 Pm-nrw j SITE LOCATION MAP EXXONMOBIL CHEMICAL COMPANY TERMINAL NO 4380 WILMINGTON, NORTH CAROLINA G nultwra NOTES: -GROUND WATER ELEVATIONS WERE MEASURED ON 9/05/02 -ELEVATION CONTOURS ARE INFERRED BETWEEN DATA POINTS -DEEP WELLS NOT USED IN CONTOURING ccm r� c tu�)I r�,iru' •v.�ita�i IMW76D �1 + ../ 1 a / � • 1 w�� k_S �. / • en to _C.1I 17 i�lF17•ti �` � �M111 :14�,.� t f ti r. MW-38 •.-... - �� MW13 e-.. MW.11 .... • _.• 1'�MACTEC DRAWN: APPFOVAL WILMINGTON. NORTH CAROLINA SCALE: s{L,�L 7r3-03 WBM !�/ y JOB: 31000-1-1560 JCP DATE: AS SHOWN DWG: 2 imap://charles.weaver%40dwq.denr.ncmail.net@cros.ncmail.net:143/... Subject: NPDES General Permit for ExxonMobil From: "Shields, Dan-Wil" <DCSHIELDS@mactec.com> Date: Fri, 26 Sep 2003 09:13:38 -0400 To: <darren.en0and@ncinail.net> CC: <charles.weaver@ncmail.net> Darren, Charles Weaver recommended that I contact you concerning a potential permit for the South Wilmington Terminal owned by ExxonMobil and located in Wilmington, North Carolina at 3340 River Road and adjacent to the Cape Fear River. ExxonMobil has operated a groundwater pump and treat system consisting of air strippers and aqueous phase carbon for effluent polishing for approximately 9 years. The system currently discharges to an infiltration gallery under Non -Discharge permit number WQ0008129. The infiltration gallery's performance has diminished to the point we cannot operated the ground -water pump and treat system at its full capacity. The average flow for the system is between 25 and 50 gallons per minute (36,000 gpd to 72,000 gpd) which is rainfall and well capacity dependent. All of our monthly monitoring indicates that the effluent is non -detect at the standard detection levels. The primary contaminant in the groundwater is para-xylene. Occasionally trace amounts of other petroleum based compounds (BTEX) are present in the influent groundwater. ExxonMobil has requested that MACTEC explore the possibility of discharging to the Cape Fear River by either a General Permit (NCG510000) for Remediation projects for the treatment of Petroleum -Contaminated Groundwater or as a modification (and separate outfall) to the existing NPDES permit for the site. The existing permit number is NCO073181 and it is our understanding that is primarily for stormwater. The questions are: Which permit should we apply under? (Modification to the existing permit or a stand alone General permit?) Since the treatment system has been constructed, what information will you need that applies to an "Authorization to Construct' permit? If we construct a separate outfall (002), what will the monitoring requirements be? Please contact me with any requests for additional information. You can reach me in Wilmington at (910) 452-1185. Thank you for your cooperation. Dan Shields MACTEC Engineering and Consulting 5710 Oleander Drive, Suite 110 Wilmington, North Carolina 28403 1 of 1 9/26/2003 10:53 AM Section 29. G.S. 143-215.1 is amended by adding a new subsection to read: (g) Any person who is required to hold a permit under this section shall submit to the Department a written description of his current and projected plans to reduce the discharge of waste and pollutants under such permit by source reduction or recycling. The written description shall accompany the payment of the annual permit fee. The written description shall also accompany any application for a new permit, or for modification of an existing permit, under this section. The written description required by this subsection shall not be considered part of a permit application and shall not serve as the basis for .the denial of a permit or permit modification.