{"operation":"document","citation":"25-0045","title":"MP Environmental Services, Inc. — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2026-03-27","effective_on":null,"summary":"25-0045 response to MP Environmental Services, Inc..","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0045.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0045.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0045","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-04/25-0045.pdf","body":"<<<PAGE 1>>>\n\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\nMarch 27, 2026\nMike Reed\nMP Environmental Services, Inc.\n3400 Manor Street\nBakersfield, CA 93308\nReference No. 25-0045\nDear Mr. Reed:\nThis letter is in response to your April 11, 2025 email requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) applicable to cargo tank certification plates\nin reserved § 178.340-10.\nWe have paraphrased and answered your questions as follows:\nQ1. Is it permissible under § 178.340-10 to leave the loading limits section empty or listed as\n“none” on the cargo tank certification plate?\nA1. No. Section 178.340-10(b)(1) requires loading limits be listed on the cargo tank\ncertification plate. Determining the loading limits is part of certification required in\n178.340-10(b).\nQ2. Is it permissible under § 178.340-10(b)(1) to provide the loading limit requirements in\ninches of mercury (inHg) instead of gallons per minute (gpm) or pounds per square inch\ngauge (psig)?\nA2. No. The requirements in § 178.340-10(b)(1) specify that the loading limit be expressed in\ngpm, psig, or both. It is the opinion of this Office that listing the pressure in inches of\nmercury (Hg) does not meet the intent of § 178.340-10(b)(1).\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nAlexander Wolcott\nActing Chief, Regulatory Review and Reinvention Branch\nStandards and Rulemaking Division\n\n<<<PAGE 2>>>\n\nJacobson\n25-0045\nJones, Jessie Jane (PHMSA)\nFrom: INFOCNTR (PHMSA)\nSent: Friday, April 11, 2025 12:42 PM\nTo: Dodd, Alice (PHMSA)\nCc: Hazmat Interps; Baker, Yul (PHMSA)\nSubject: FW: Cargo Tank Interpretation\nAttachments: Arizona inspection 11_26_24-dataQ.pdf; Arizona inspection 11_26_24.pdf; ARIZONA\nINSPECTION-11.26.24-1.pdf; Arizona Inspection -11-24-24.jpg; 20151107_124601.jpg\nHi Alice,\nPlease see the below interpretation request. Let us know if you need anything.\nSincerely,\nJanaye\nFrom: Mike Reed <mwreed@mpenviro.com>\nSent: Friday, April 11, 2025 12:02 PM\nTo: INFOCNTR (PHMSA) <INFOCNTR.INFOCNTR@dot.gov>\nSubject: Cargo Tank Interpretation\nYou don't often get email from mwreed@mpenviro.com. Learn why this is important\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do not click on links\nor open attachments unless you recognize the sender and know the content is safe.\nGood Morning,\nI have a request for an interpretation on a cargo tank issue, our driver was given this violation concerning 178.340-10\nloading limits. The spec plate on the tank does not have a G.P.M or P.S.I.G markings filled in but does have inches in\nMercury box filled in because it is a vacuum loaded tank (picture included).\nI contacted the manufacturer and spoke to an engineer and he stated they did not have any interpretation or letter from\nRSPA concerning this issue. I would like to get a ruling on this, since this is a Vacuum loaded tank. I have another Vacuum\nloaded tank which also has the G.P.M or P.S.I.G with none listed in those areas (picture included) and no HG markings. Is\nthis illegal also? Thank-you for your time.\nMike Reed\nMP Environmental Services, Inc.\n3400 Manor Street\nBakersfield, CA 93308\nPhone 661-393-1088\nCell 661-319-4799\nFax 661-393-0508\n1\n\n<<<PAGE 3>>>\n\nDataQs\nFederal Motor Carrier Safety Administration\nU.S. Department of Transportation\nDetailed view of ID# 4901951\nDate Entered: 12/04/2024\nReport State: AZ\nType: Inspection - Incorrect Violation\nReport Date: 11/26/2024\nReport Number: 1034700589\nStatus: Closed - No Data Correction Made\nUSDOT#: 441566 (SMS)\nAssigned Agency#: 602-223-2413\nAssigned to: AZ DPS\nRequest Summary\nRequestor Profile\nName: MIKE REED\nAddress: 3400 MANOR ST\nUsername: cd004415660000607406\nCity/State/Zip: BAKERSFIELD, CA 93308\nUser Role: Validated Motor Carrier\nPhone: 661-3194799\nCompany/Agency Name: M P ENVIRONMENTAL SERVICES INC\nFax:\nUSDOT#: 441566 (SMS)\nEmail Address: mwreed@mpenviro.com\nExplanation of Request for Data Review\nWhere did you view the data you want reviewed?: Inspection Report\nSupporting Document: ARIZONA INSPECTION-11.26.24.pdf\nSupporting Document: 20161004_072629.jpg\nSupporting Document: ARIZONA-11.26.24-1.pdf\nStatus: Closed - No Data Correction Made | Federal Violation Code: 178.340(10)\nFederal Violation Description:\nSPECIFICATION PLATE\nWhy should the violation be reviewed?:\nI would like this violation removed, the data plate contains the required information. I have included a copy of the data plate and the title 49 section, if you look at the picture and besides the \"loading limits\"\nsection, there are three boxes: GPM, PSIG, IN-HG, Since this a vacuum tank and it is loaded by vacuum, the amount is listed as 29 Inches of Mercury, If you look at the \" Unloading limits\" section and beside it, the\nDetailed Information from Inspection Record\nReport State: AZ\nReporting Officer ID: 10347\nReport Number: 1034700589\nCity/Location: CHANDLER AZ\nDate: 11/26/2024\nEvent County: MARICOPA\nEvent Time: 8:38 AM\nState: AZ\nCarrier Information from Inspection Report\nCarrier Name: MP ENVIRONMENTAL SERVICES INC\nCity: BAKERSFIELD\nUSDOT#: 441566 (SMS)\nCountry: US\nMC/MX#:\nState: CA\nAddress (1): 3400 MANOR STREET\nZip: 93308\nAddress (2):\nDriver Information from Inspection Record\nDriver Name: JOHN BARWICK\n\n<<<PAGE 4>>>\n\nResponse List\nResponse Date: 02/05/2025 10:03 AM\nStatus Changed to: Closed - No Data Correction Made\nEntered By: Chesney Becker\nStatus Prior to Response: Open - In Review\nPhone: 0-0\nAgency Name: AZ DPS\nResponse To: 178.340(10)\nSupporting Document: NTTC Regs.PDF\nIN HG.\nResponse Description: Please see the attached regulations that apply. Since this trailer is a MC307/312 tank, per page 243 for loading limits, it has to have an amount in GPM or PSIG - nothing about\nResponse Date: 01/31/2025 07:39 PM\nStatus Changed to:\nEntered By: MIKE REED\nStatus Prior to Response: Open - In Review\nPhone: 661-3194799\nAgency Name: Validated Motor Carrier\nResponse To: 178.340(10)\nResponse Description: I submitted this almost 2 months ago, Has there been a final determination on this?\nDocuments List\nSupporting Documents\nTitle Name\nDocument Name\nDate Uploaded\nSize\nRegulations\nNTTC Regs.PDF\n02/05/2025 10:03 AM\n3.16 MB\nLaw Enforcement report\nARIZONA-11.26.24-1.pdf Original Upload\n12/04/2024 10:56 AM\n0.90 MB\nLaw Enforcement report\nARIZONA INSPECTION-11.26.24.pdf Original Upload\n12/04/202410:56 AM\n0.95 MB\nOther evidence to support RDR\n20161004_072629.jpg Original Upload\n12/04/202410:57 AM\n3.51 MB\nadd a response with further details using the buttons above. The more information you provide now, the faster your request can be processed! When the assigned to agency has further questions or requests\nSYSTEM MESSAGE: You have submitted your request. To help expedite the review process, submit all of the documentation you may have to support your request. You may upload or fax in documentation, or\nFor example, the Safety Measurement System (SMS) Website is updated monthly based on a snapshot of the data. To review crash and inspection records prior to the snapshot, visit the FMCSA Portal. The Pre-\nany documentation, it will respond above and an email copy will be sent to you. Once the request is closed and a correction is made to the record, you will see it on the next update of the respective system.\ns://ai.fmcsa.dot.gov/SMS/HelpCenter/Index.aspx#ifaq30897.\nEmployment Screening Program (PSP) report is updated monthly based on the same snapshot used on the SMS Website. For more details about the update schedule, visit the SMS Information Center at http\n\n<<<PAGE 5>>>\n\n11/26/24, 10:12 AM\nFMCSA - Inspection Platform\nDRIVER/VEHICLE EXAMINATION REPORT\n1550's\nArizona Department of Public Safety\nInspection Date: 11/26/2024\nReport Number: AZ1034700589\nPhoenix, AZ 85005\nPO Box 18410\nInspection Level: I\nStart: 08:38 AM MST End: 10:15 AM MST\nEmail/web: returndver@azdps.gov\nPhone: 602-223-2000\nHM Inspection Type: Bulk\n400 MANOR STREET\n1 P ENVIRONMENTAL SERVICES INC\nDriver: Barwick, Kelly, John\nBAKERSFIELD, CA, 93308\nLicense#t D06636224\nLocation: RIGGS 168\nMC/MX#:\nUSDOT#: 441566\nState# AZ\nMilePost: 168\nDate of Birth# 04/04/1962\nHighway: 1-10\nCounty: MARICOPA\nState#t:\nCoDriver:\nshipper: KINDER MORGAN\nFax#:\nPhone#: 6613931151\nLicense#\nBill of Lading:\nState#\nOrigin: TUCSON, AZ, US\nDate of Birth#\nDestination: PHOENIX, AZ, US\nCargo: Hazardous Materials\nVEHICLE IDENTIFICATION\nUnit Type Make Year State Plate# Equipment ID\n2 ST BIEN 1023 MT 3623366\nTT PTRB 2023 MT PA28346\nVIN\nGVWR Mileage CVSA# CVSA Issued # OOS Sticker\n3297\nIXPXDP9X4PD891746 52,000\n10BGX5214MFOA272068,000\nVIOLATIONS ATTRIBUTABLE TO THE MOTOR CARRIER\nVio Code\nSection\nUnit Oos Citation # Verify Violations Discovered\n172.202A2-HMSPS\n172.202 (a)(2)\nN\nN\naviation, turbine engine\n178.340-10-HMP\n178.340-10\nN\nHM (Packaging) - MC 306/307/312 certification plate.:\nSPECIFICATION PLATE MISSING LOADING PSIG AND/OR\nGAL/MINUTE THE BOXES ARE EMPTY. PICTURE TAKEN\n396.5B-L\n396.5(b)\n2\nN\nU\nLubrication - Oil or grease leak: OIL LEAK FROM RIGHT SIDE OF\nTRAILER SEE PICTURES\nHazardous Materials\nHM Type: Bulk\nCargo Tank Specification: 307\nPlacards Required: Yes\nHM Class\nRep Quantity\nHM Waste\nUN/NA#\nProper Shipping Name\n3 Flammable\nN\nN\nUN1863\nHMSP Required? No\nFuel, aviation, turbine engine\nHMSP in Possession of Driver? N/A\nSpecial Checks:\nNo Data for Special Checks.\notor Carier suited a be prosecute with penalties tip to to as they are applicable to motor carriers and drivers. False certifications of the require\ne undersigned certifies that all violations noted on this report have been corrected and action has been taken to assure compliance with the Feder\nSignature Of Repairer X:\nFacility:\nDate:\nReport Prepared By:\nTpr Darius Windels.\nBadge #: Radio#:\n10347\nKELLY JOHN BARWICK\nCopy Received By:\nPage 1 of 2\nX-\n441566 AZ AZ1034700589\nittps://safespect.fmcsa.dot.gov/#/inspection/confirm\n1/2\n\n<<<PAGE 6>>>\n\n§ 178.340-10\nrequired in paragraph (b) of this subsection, located on the right side,\nments of a different MC Specification, there shall be a metal plate\ning the applicable specification is legible at all times the cargo tank is\ninspection. Details pertaining to the multipurpose configuration shall\nnear the front of each compartment, in a place readily accessible for\nin complete compliance with such specifications.\nthe plates (or plate assembly) shall be secured in such a manner as to be\nThe mounting of\n'paragraph (c) of this section.\nalso be clearly indicated on the manufacturer's certificate required in\ncapable of retaining the plate when subjected to normal operating\ntion plate shall be used. The plate shall contain at least the informa-\nconditions.\nThe same marking size and method used on the certifica-\nrequirements of one specification and may be physically altered to\n(i) If a cargo tank is constructed in accordance with the\ntion contained below:\ntered to accommodate a commodity not requiring a specification tank\nmeet another cargo tank specification in this part; or physically al-\n(tificate required in paragraph (c) of this subsection and the tank mounted\nsuch alterations shall be clearly indicated on the manufacturer's cer-\nEQUIPMENT NECESSARY\nSPECIFICATION IDENTIFICATION MC\nmulti-purpose plate required in paragraph (b)(2) of this section.\nVents\nQuantity!\nwhich does not meet all of the applicable specification requirements,\n(2) Specification shortages. If a cargo tank is manufactured\nFusible\nPressure actuated\n¡thereby requiring subsequent manufacturing involving the installation\nFrangible\npermissible for the original manufacturer to affix the metal certifica-\nof additional components, parts, appurtenances or accessories, it is\nProduct discharge\ntion requirements not complied with shall be indicated on the\ntion plate required in paragraph (b) of this subsection. The specifica-\nTop\nPressure unloading fitting\nBottom\nmanufacturer's certificate required in paragraph (c) of this subsection.\ndate such compliance is accomplished shall be stamped on the metal\nWhen the cargo tank is finally brought into complete compliance, the\nCovers\ncertification plate.\ndate and concern (manufacturer or carrier) accomplishing complete\nThe certificate shall indicate the pertinent details,\nFill opening\nManhole\ncompliance.\ntank compartment if constructed to a different specification, must\n(b) Metal certification plate. After July I, 1985, cach cargo tank, or\nNC shall follow the number required If cargo tank is not so equipped the word \"NONE\" shall be\n'The number required to meet appicable specification If no physical change is required the letters\ninserted\nsupporting structure.\nhave a metal certification plate attached to its shell or to an integral\ncorrosion, must be located on the left side (on the right side prior to\nThe metal certification plate, not subject 1o\nthe applicable specification requirements and the appropriate multi-\n(I) Color coding: Those parts which must be changed or added to meet\nFach plate shall be permanently affixed by means of brazing, welding,\nJuly 1, 1985) near the front in a place readily accessible for inspection.\nMC 306 RED\npurpose plate shall be identified using the following colors:\nmarked in characters at least 3/16-inch high by stamping, embossing.\nsoldering, riveting, or other equally suitable means.\nThe plate must be\nMC 312 YELLOW\nMC 307 GREEN\nitself at least the information prescribed in paragraphs (b)(1) and\nor other means of forming letters into or on the metal of the plate\nNon Spec. BLUE\nmarking thereon. A combination ASME/DOT certification plate is\n(b)(2) of this section. The plate may not be painted as to obscure the\nthe appropriate MC Spec. Number\nAdditionally those parts to be changed or added shall be stamped with\ncertificate\nA certificate signed by a responsible official of the manu-\n• (C)\nManufacturer's\nauthorized.\nfacturer of the cargo tank, or from a competent testing agency, certi-\njother specification (or to accommodate a commodity not requiring a\n(1) If a cargo tank is to be physically altered to meet an-\nfying that each such cargo tank is designed, constructed and tested in\ncable specification shall be procured, and such certificate shall be re-\naccordance and complies with the requirements contained in the appli-\n¡fication Identification. Additionally the metal multi-purpose plates\nspecification tank) such combinations shall be indicated beside Speci-\nemployed by him plus one year. In lieu of this certificate, if the motor i\nrained in the files of the carrier during the time that such cargo tank is\nrequired in subparagraph (2) of this paragraph are required\nquirements of the specification by his own test, he shall similarly\ncarrier himself elects to ascertain that any such tank fulfills the re-\nVehicle manufacturer\nSpecification identification ' DOT MC 306; or MC 307; or MC 312\nretain the test data.\nOriginal test date\nDate of manufacture\nCertificate date\nMC 306\nTest pressure\nDesign pressure\np.s.1.g\n§ 178.341-1 General requirements.\n§ 178.341 Specification MC 306; cargo tanks.\nShell material\nHead material\np.s.1.g.\n(a) Specification MC 306 cargo tanks must comply with the gencral\nWeld material\nspecific requirements contained in this section\ndesign and construction requirements in §178.340 in addition to the\nLining material\nMaximum product load\nNominal tank capacity by compartment (front to rear)\nLoading limits\n-. 8.p.m.\nand/or p.s.i.g.\n1bs.\nUS Gal\n(b) Design pressure.\nbe less than that pressure exerted by the static head of the fully loaded\nThe design pressure of each cargo tank shall not\ntank in the upright position\nUnloading limits\n_ g.p.m. and/or p.s.i.g.\n§ 178.341-2 Thickness of shells, heads, bulkheads and baffles.\nauthorized in $178.340-3 shall be predicated on not exceeding the\n(a) Material thickness.\nThe minimum thicknesses of tank material\n((Al.), Mild Steel (MS): High Strength Low Alloy (HSLA): Austenitic Stainless Steel (SS)\nThe following material designations (or combinations thereot) must be added. Aluminum Alloy\nexample \"DOT MC 106-AL. for cargo tanks made of aluminum. A multi-purpose cargo tank\nFor\nthan those indicated in Tables / and Il on page 248.\nmaximum allowable stress level (§178.340-4(a)) but in no case less\nexample would he \"Combination MC 306 SS-107 SS \"\n(1) Product density.\nIl are minimums based on a maximum 7.2 pounds per gallon product\nThe material thicknesses contained in Tabie I and\nphysically altered, metal multi-purpose plates shall be mounted adja-\n(2) Metal multi-purpose plate.\nIf a cargo tank is to be\nweight. If the tank is designed to haul products weighing more than 7.2\ncent to the metal certification plate readily accessible for inspection.\nminimum thickness of heads, bulkheads, baffles or shell sheets shall be\npounds per gallon, the gallon per inch value used to determine the\nThe mounting of the plates shall be such that only the plate identify-\nthe actual section capacity required in gallons per inch multiplied by\n243\n\n<<<PAGE 7>>>\n\nFONG OU LAC. WISTUNSITOS.A\nMFR'S SERIAL NO.\n214М0Д2720\nD.O.T. SPEC.\nDATE MERA\nORIG TEST DATE-\nDESIGN PRESSURE\n1 PSg\n*HEAD MATERIAL\nMAT EST PRESSUNE 55\nPSG\nSu 200-T.\n31A\n-SS\nSHELLMATERNL\nSA30AT:\n316\nSS\nWELD MATERINEE\nMANOLSS\nLANG LATERLL\nNOMINAL CAPALU DBYCOMRER\nI PRONY TO REARE\nUS GALS\nMAX. PRODUCT LOAD:\nSUBS.\nMAX PRODUCTWTS\n:LES/BALS\nCLOADNG LIMITS E\nHONG.\nCARUNLDADING LIMES\nCPM!\ntapu- n\"\nS\n-2260.\n\n<<<PAGE 8>>>\n\nCERTIFICATION PLATE\nVEHICLE MANUFACTURER_\nACRO I RAILER, CO.\nMFG. SER. NO.6469\nV.I.N. 1A91145c5J1005006\nSPECIFICATION IDENTIFICATIONMC-307-312-SS\nDATE OF MANUFACTURE 9\nDATE 1\nSERIA\nORIGINAL TEST DATE-\nMODE\nCERTIFICATION DATE\nDESIGN PRESSURE 35- VI\n18 87\nTHIS\nTEST PRESSURE557\nACU\nPSIG\nAPPL\nHEAD MATERIAL SA-\n40-616\nPSIG\nVEHI\nSHELL MATERIALSA-240-3161 | 61 TD.\nLE 4KR. 187 IN.\nIN E\nMAN\n- 8 GA.\nWELD MATERIAL ER-316L-S1\nGRO\nGRO\nLINING MATERIALNONE\nACI\nNOMINAL TANK CAPACITY BY COMPARTMENTS (FRONT TO REAR)\nMAXIMUM PRODUCT LOAD.\n020\nU.S. GALS.\nLOADING LIMITS NONE\nLBS.\nGPM and/or PSIG\nUNLOADING LIMITS 35\nGPM and/or PSIG O","truncated":false,"body_characters":18033}