Section 21.40 - Underground Utilities(a) General. (1) Encasement. Attached Graphic
(A) Underground utility facilities crossing the highway shall be encased as shown in Figure §21.40(a)(1). The encasement must be a single structure with no open seams. If used, polyvinyl chloride (PVC) and high-density polyethylene (HDPE) pipe shall be glued with an appropriate adhesive, bonded, or mechanically fastened. Steel pipe shall be welded or bolted.(B) The encasement may be of metallic or non-metallic material, depending on the type of utility facility. If the encasement is not schedule 40 polyvinyl chloride (PVC) pipe, high-density polyethylene (HDPE), or made of steel, the utility must demonstrate that the encasement is adequate for the expected loads and stresses.(C) The length of any encasement shall extend, as applicable, to within five feet of the right of way, two feet of a connecting longitudinal line, or five feet beyond the face of the curb, whichever is greatest. These lengths of encasement include areas under center medians and outer separations. At a district's discretion, the district may waive the encasement requirement under center medians or under outer separations that are more than 76 feet wide. At a district's discretion and after considering traffic volume, condition of highway, maintenance responsibility, and district practice, the district may waive the encasement requirement under side road entrances.(D) Unless waived by the district, an encasement is required for installation under other department structures, such as retaining walls, headwalls, and sound walls.(2) Depth. (A) Underground utility facilities shall be installed at the applicable minimum depth of cover shown in Figure §21.40(a)(2)(A) unless the district requires or authorizes a different depth under this paragraph. Attached Graphic
(B) The district may require a greater depth at specific areas due to site conditions including areas such as culvert crossings, drainage areas, and future project considerations.(C) The district may require a greater depth based on distance from edge of pavement.(D) Where placements at the depths in this section are impractical or where unusual conditions exist, the department may allow installations at a lesser depth, but will require other means of protection, including encasement or the placement of a reinforced concrete slab. Reinforced concrete slabs or caps shall meet the following standards: (i) width -- five feet, or three times the diameter of the pipe, whichever is greater;(ii) thickness -- a minimum of six inches;(iii) reinforcement -- #4 bars at 12 inch centers each way or equivalent reinforcement; and(iv) cover -- no less than six inches of sand or equivalent cushion between the bottom of the slab/cap and the top of the pipe.(3) Manholes.(A) Manholes may not be installed unless necessary for installation and maintenance of underground lines. In no case shall a manhole be placed or permitted to remain in the pavement or shoulder of a highway. However, on noncontrolled access highways in urban areas, the district may, in its discretion, allow existing lines to remain in place under existing or proposed highways. In these cases, manholes may remain in place or be installed under traffic lanes of low volume highways in municipalities only if measures are taken to minimize the installations and to avoid locating them at intersections or in wheel paths.(B) To conserve space, a manhole's dimensions must be the minimum acceptable by appropriate engineering and safety standards. The only equipment that may be installed in manholes located on the right of way is equipment that is essential to the normal flow of the utility facility, such as circuit reclosers, cable splices, relays, valves, and regulators. Other equipment, such as substation equipment, large transformers, and pumps, shall be located outside the right of way.(C) Inline manholes are the only type permitted within the right of way. The width dimensions may not be larger than necessary to hold equipment involved and to meet safety standards for maintenance personnel. Outside width, the dimension of the manhole perpendicular to the highway, may not exceed ten feet, with the length to be held to a reasonable minimum. The outside diameter of the manhole chimney at the ground level may not exceed 36 inches, except that if the utility demonstrates necessity, the district may, at its discretion, allow an outside diameter of up to 52 inches. The top of the roof of the manhole must be five feet or more below ground level.(D) All manhole covers shall be installed flush with the ground or pavement structure. In order to minimize vandalism, manhole covers must weigh at least 175 pounds. Manhole rings and covers must be designed for HS-20 loading.(E) Manholes shall be straight, inline installations with a minimum overall width necessary to operate and maintain the enclosed equipment. The utility is responsible for any adjustment of the manhole rim that may be needed to meet grade changes.(4) Installation.(A) A department permit is required for all installation of utility facilities in the department's right of way.(B) If the installation of the utility facility deviates from the approved location, the district, at its sole discretion, may require the adjustment of the utility facility to the approved location.(C) Utility facilities placed beneath any existing highway shall be installed by boring or tunneling. Jacking may not be used unless approved in writing by the district. The use of explosives is prohibited. Pipe bursting or fluid/mist jetting may not be used unless approved in writing by the department. Longitudinal installation of a utility facility across driveways and intersecting roadways shall be bored. Open trench construction through intersecting roadways and driveways may not be used unless approved in writing by the district engineer.(D) To preserve and protect trees, shrubbery, and other aesthetic features within the department's right of way, the district may specify the extent and methods of tree removal, tree trimming, or the replacement of the aesthetic features. Landscape areas in the department's right of way that are associated with residences shall be bored, unless the district approves another method. The district may require boring on steep slopes where vegetation may be damaged.(E) For rural, uncurbed highway crossings, all borings shall extend beneath all travel lanes. Unless precluded by right of way limitations, the following clearances are required for rural highway crossings:(i) 30 feet from all freeway mainlanes and other high-speed (exceeding 40 mph) highways except as indicated in clauses (ii) - (iv) of this subparagraph;(ii) 16 feet for high-speed highways with current average daily traffic volumes of 750 vehicles per day or fewer;(iii) 16 feet for ramps; or(iv) ten feet for low-speed (40 mph or less) highways.(F) The reamed bore size may not exceed 40 percent of the outside diameter of the encasement, and a reamer that allows the natural wet grout to remain shall be used. Alternately, annular voids greater than one inch between the bore hole and the carrier line or encasement], if used, shall be filled with a slurry grout or other flowable fill acceptable to the department to prevent settlement of the highway facility.(G) Unless an open-trench installation is approved by the district in locations where adequate space is not available, all borings for curbed highway crossings shall extend beneath travel and parking lanes and beyond the back of curb and sidewalk, plus: (i) 30 feet from facilities with speed limits of 40 mph or greater; or(ii) five feet from highway facilities with speed limits of less than 40 mph or less.(H) Where circumstances necessitate the excavation of a bore pit or the presence of directional boring equipment closer than 30 feet from the edge of pavement, approved protective devices shall be installed for protection of the traveling public in accordance with § 21.38 of this subchapter (relating to Construction and Maintenance). Bore pits shall be located and constructed in such a manner as not to interfere with the highway structure or traffic operations. Shoring shall be utilized for the protection of the highway facility, and its use and design must be approved by the district.(I) All traffic control devices, including signs, markings, or barricades used to warn motorists and pedestrians of the construction activity must conform to the TMUTCD.(J) When trenching longitudinally, backfill or stabilized sand shall be compacted to densities equal to that of the surrounding soil. Compaction must meet all requirements listed in Item 400, relating to excavation and backfill structures, of the department's publication, Standard Specification for Construction and Maintenance of Highways, Streets, and Bridges.(K) Longitudinal installations shall be in uniform alignment with the department's right of way and as near as practical to the edge of the department's right of way line. Consideration shall be given to allow safe clearance from adjacent installations.(L) An additional 12 inches of depth are required for installations within 50 feet of waterways, ditches, channels, creeks, or culverts.(M) As assigned corridors within the department's right of way are finite at particular depths, the district may require the placement of a utility facility below other facilities at necessary clearances. The district may require encasements to allow the repair or replacement of the utility facility without disturbing adjacent utility facilities.(5) Nonmetallic pipe detection. Where nonmetallic pipe is installed, whether longitudinally or at a crossing, a durable metal wire or other district-approved means of detection shall be concurrently installed.(6) Unsuitable conditions. The following conditions are generally unsuitable or undesirable for pipeline crossings and shall be avoided: (B) locations near footings or bridges and retaining walls;(C) crossing intersections at-grade or ramp terminals;(D) locations at cross-drains where the flow of water may be obstructed;(E) locations within basins or underpasses drained by pump if the pipeline carries a liquid or liquefied gas; or(F) terrain where minimum depth of cover would be difficult to attain.(7) Clearances. Except as specified in this subchapter, there shall be a minimum of 12 inches vertical and horizontal clearance between a new utility facility and an existing utility facility, unless a greater clearance is required by the district. However, if an installation of another utility facility or highway feature cannot take place without disturbing an existing utility facility, the district may require a minimum clearance of 24 inches.(8) Drainage easements. Where it is necessary for pipelines to cross department drainage easements outside of the right of way, the depth of cover shall be as specified for each type of utility facility. In cases where soil conditions are such that erosion might occur, or where it is not feasible to obtain specified depth, it shall be the responsibility of the utility to install retards, energy dissipators, encasement, or concrete or equivalent slabs/caps over the pipe, as approved by the department. Where grades on the pipelines must be maintained, such as gravity flow sewer lines, each case will be reviewed on an individual basis. The main purpose of the department's drainage easement is to carry drainage water and the drainage may not be obstructed. The utility is responsible for obtaining any other approvals or rights required to occupy the drainage easement.(9) Existing installations in a highway or transportation project. At the district's discretion, existing longitudinal utility facilities in a highway or transportation project that otherwise meet the requirements of this subchapter may remain in place if the utility facilities: (A) can be maintained in accordance with § 21.37(b)(2) of this subchapter (relating to Design); and(B) are not located under the pavement structure or shoulder of any proposed or existing highway.(10) Markers. If a high pressure pipeline crosses a highway, the utility shall place a readily identifiable, durable, and weatherproof marker over the centerline of the pipe at each right of way line. Readily identifiable, durable, and weatherproof markers shall be placed at a minimum distance of 500 feet apart or line of sight at the right of way line for pipelines installed longitudinally within the right of way. All markers shall indicate the name, address, emergency telephone number of the utility, and offset from the right of way line for longitudinal placement. For gas, petroleum, or saltwater pipelines, the pipeline product, operating pressure, and depth of pipe below grade shall also be indicated on the markers. At locations where underground utility facilities have been allowed to cross at an angle other than 90 degrees to centerline, the district may require additional markers in the medians and outer separations of the highway.(b) Gas and liquid petroleum pipelines and saltwater pipelines.(1) Low-pressure pipelines.(A) Depth of cover for crossings. Depth of cover is the depth to the top of the encasement, or the carrier pipe if encasement is not used. Where materials and other conditions justify, such as on existing pipelines remaining in place, the district may require a minimum depth of cover under the pavement structure of 12 inches or one-half the diameter of the pipe, whichever is greater. (i) For encased low-pressure gas pipelines, the minimum depth of cover is:(I) 60 inches or one-half the diameter of the pipe, whichever is greater, below the lowest point of the crossed grade; or(II) 48 inches if the pipeline is outside of the pavement structure or 60 inches under ditches (original unsilted flowline).(ii) For unencased low-pressure gas pipelines, the minimum depth of cover is:(I) 60 inches under the lowest point of the crossed grade;(II) 48 inches if the pipeline is outside of paved areas; or(III) a lesser depth than applicable under subclause (I) or (II) of this clause if the lesser depth is authorized by the district where a reinforced concrete slab is used to protect the pipeline.(B) Depth of cover for longitudinal placement. The minimum depth of cover for longitudinal installations is 48 inches.(C) Encasement. Low-pressure gas pipelines crossing the pavement shall be placed in a high-density polyethylene (HDPE) or equivalent encasement. The district may waive this encasement requirement if:(i) the pipeline is:(I) of welded steel construction; and(II) is protected from corrosion by cathodic protective measures or cold tar epoxy wrapping; and(ii) the utility signs a written agreement that the pavement will not be cut for pipeline repairs at any time in the future.(D) Vents. One or more vents shall be provided for each encasement or series of encasements. For encasements longer than 150 feet, vents shall be provided at both ends. On shorter encasements, a vent shall be located at the high end with a marker placed at the low end. Vents shall be placed at the right of way line immediately above the pipeline, situated so as not to interfere with highway maintenance or be concealed by vegetation, and may not be greater than six inches in diameter. The utility's name, address, and emergency telephone number shall be shown on each vent.(E) Aboveground appurtenances. Except for vents, pipeline markers, and gas rectifiers, aboveground utility appurtenances for gas lines are prohibited within department's right of way.(2) High-pressure pipelines and saltwater pipelines.(A) Depth of cover for crossings. (i) Depth of cover is the depth to the top of the encasement or carrier pipe if an encasement is not used. Where materials and other conditions justify, such as on existing lines remaining in place, the district may approve a minimum depth of cover under the pavement structure of 48 inches or one-half the diameter of the pipe, whichever is greater. For encased high-pressure pipeline, the minimum depth of cover is: (I) 60 inches or one-half the diameter of the pipe, whichever is greater, below the lowest point of the crossed grade unless a greater depth is required by the district; or(II) 48 inches if the pipeline is outside of the pavement structure, or 60 inches if under a ditch, below the lowest point of grade.(ii) Where a reinforced concrete slab is used to protect the pipeline, the district may authorize a reduction in the depths specified in this subparagraph.(iii) For unencased high-pressure pipelines, the minimum depth of cover is as follows:(I) 60 inches under the lowest point of the crossed grade, subject to subparagraph (D) of this paragraph; or(II) 60 inches under the lowest point of grade if the pipeline is placed outside the pavement structure or under a ditch.(B) Depth of cover for longitudinal placement. The minimum depth of cover is 48 inches.(C) Encasement. The encasement must be a vented steel pipe.(D) Unencasement.(i) Where encasement is not employed, the utility shall show that the welded steel carrier pipe will provide sufficient strength to withstand the internal design pressure and the dead and live loads of the pavement structure and traffic. Additional protective measures must include:(I) heavier wall thickness, higher factor of safety in design, or both;(II) adequate coating and wrapping;(III) cathodic protection; and(IV) the use of Barlow's formula regarding maximum allowable operating pressure and wall thickness, as specified in 49 CFR § 192.105.(ii) Shallow anode bed types exceeding 48 inches in width may not be used in the department's right of way. All others must have a depth of coverage of at least 36 inches. Deep well anode beds of up to 60 inches in diameter are acceptable. Rectifier and meter loop poles shall be placed at or near the right of way line.(iii) The minimum length of the additional protection is the same as that required for an encased crossing.(iv) The district may allow existing lines under low-volume highways to remain in place without encasement or extension of encasement if they are protected by a reinforced concrete slab or equivalent protection or if they are located at a depth of five feet under the pavement structure and not less than four feet under a highway ditch.(E) Vents. Vents shall be installed at both ends of an encasement, regardless of length, with a marker on at least one end. Vents shall be placed at the right of way line immediately above the pipeline, situated so as not to interfere with highway maintenance or be concealed by vegetation. The utility's name, address, and emergency telephone number shall be shown on each vent marker.(F) Aboveground appurtenances. Except for vents, pipeline markers, and gas rectifiers, above ground appurtenances are prohibited within department's right of way.(c) Water lines. (1) Material type. All material types used for water lines shall conform to American Water Works Association, applicable local requirements, and 30 TAC § 290.44(a) (relating to Water Distribution).(2) Depth of cover. The minimum depth of cover is 36 inches from the lowest point of grade for longitudinal utility facilities, and 60 inches from the lowest point of grade for all crossings.(3) Encasement. Water lines crossing under paved highways shall be placed in an encasement pipe within the department's right of way. Existing water lines that are 24 inches or greater in diameter may be allowed to remain unencased under the pavement of new low volume highways, provided that the depth and all other requirements of 30 TAC § 290.44 are met.(4) Manholes. The width dimensions of manholes may not be larger than is necessary to hold equipment involved and to meet safety standards for maintenance personnel. The maximum inside diameter of the manhole chimney may not exceed 48 inches. The outside diameter of the manhole chimney at the ground level may not exceed 36 inches.(5) Aboveground appurtenances.(A) Fire hydrants and valves. When feasible, fire hydrants and blow-off valves shall be located at the right of way line. Fire hydrants may not be placed in the sidewalk or any closer than five feet from the back of the curb. Valve locations shall be placed so as not to interfere with maintenance of the highway.(B) Water meters. Individual service meters shall be placed outside of the department's right of way. Master meters for a point of service connection may be placed in a manhole with a maximum width of 48 inch inside diameter. If additional volume is required, a manhole with a neck of 60-inch depth shall be used.(d) Non-potable water control facilities. (1) Applicability. This subsection applies to agricultural irrigation facilities, water control improvement districts, municipal utility districts, flood control districts, canals, and similar non-potable water control facilities.(2) Depth of cover. The minimum depth of cover, regardless of type of pipe used, is 36 inches for longitudinal utility facilities, and 60 inches from the lowest point of grade for all crossings.(3) Encasement. All non-potable water control lines crossing under paved highways shall be encased. At the district's discretion, encasement may be omitted under center medians and outer separations that are more than 76 feet wide.(4) Location and design requirements. Longitudinal buried pipe facilities installed within the right of way must conform with § 21.41(c) of this subchapter (relating to Overhead Electric and Communication Lines), consistent with the clearances applicable to all roadside obstacles. Open ditch facilities may not be installed longitudinally within the department's right of way. Aboveground appurtenances within the horizontal clearance of the highway facility are prohibited.(5) Levee/ditch travel road location. Coordination with and approval by the district is required where levee/ditch travel roads intersect the highway.(e) Sanitary sewer lines. (1) Material type. All material types used for sanitary sewer lines must conform to applicable provisions of 30 TAC Chapter 217 and applicable local requirements.(2) Depth of cover. The minimum depth of cover for gravity lines is 30 inches and not less than 18 inches below any pavement structure. The minimum depth of cover for pressurized sanitary sewer lines is 60 inches for crossings and 36 inches for longitudinal utility facilities.(3) Encasement. All crossings of paved highways within the right of way shall be encased. At the district's discretion, the district may exempt the encasement requirement under center medians and outer separations that are more than 76 feet wide.(4) Manholes. Manholes serving sewer lines up to 12 inches shall have a maximum inside diameter of 48 inches. For lines larger than 12 inches, the manhole inside diameter may be increased an equal amount, up to a maximum diameter of 60 inches. Manholes for large interceptor sewers shall be designed to keep the overall dimensions to a minimum. The outside diameter of the manhole chimney at the ground level may not exceed 36 inches.(5) Lift stations. Lift stations and pump stations for sanitary sewer lines shall be located outside of the department's right of way.(f) Electric lines Lines. (1) Depth of cover for longitudinal placement. All underground electric lines placed longitudinally within the right of way may be installed by direct bury at depths equal to or greater than 48 inches.(2) Depth of cover for crossings. The minimum depth of cover for underground electric lines is 60 inches below the lowest point of the crossed grade.(3) Encasement. Electric lines crossing the roadway shall be encased in high-density polyethylene(HDPE) or comparable material with a strength greater than or equal to ductile iron, with satisfactory joints, or materials and designs that provide equal or better protection of the integrity of the highway system and resistance to damage from corrosive elements to which they may be exposed. The lines shall be buried a minimum of 60. Encasement shall be provided as outlined in this section.(4) Installation. The utility facility shall be located as set forth in § 21.37(b) of this subchapter (relating to Design).(5) Aboveground appurtenances. (A) Aboveground appurtenances installed as part of an underground electric line shall be located at or near the right of way line, and may not impede highway maintenance or operations.(B) Structures that are larger in plan view than single poles may be placed on the right of way if: (i) the installation does not hinder highway maintenance operations;(ii) the housing is placed at or near the right of way line;(iii) the installation does not reduce visibility and sight distance of the traveling public;(iv) the dimensions of the housing are minimized, particularly where the need to allow space for highway improvement or accommodation of other utility lines is apparent;(v) the outside width, length (longitudinal with respect to the right of way), and height dimensions of the aboveground portion of the housing do not exceed 36 inches, 60 inches, and 54 inches, respectively;(vi) the supporting slab does not project more than three inches above the ground line, nor extend more than 12 inches on either side of the housing structure; and(vii) the installation is compatible with adjacent land uses.(6) Manholes. Manholes serving electric lines shall conform to the requirements of this section.(g) Underground communication lines. (1) Joint duct banks. Where a department joint duct bank is available, a utility shall install a utility facility in the duct bank unless otherwise authorized by the district.(2) Depth of cover for crossings. The minimum depth of cover for communication lines is 60 inches below the lowest point of the crossed grade.(3) Depth of cover for longitudinal placement. The minimum depth of cover for the longitudinal placement of communication lines is 48 inches. If site conditions warrant, the district may allow communication lines to be installed at a depth of 42 inches.(4) Encasement. Communication lines shall be encased in accordance with Figure §21.40(g)(5) for all crossings. The external encasement must be a high-density polyethylene (HDPE) pipe with a size dimension ratio of 11 or less or an equivalent encasement. A carrier cable inside of the external encasement must have an additional internal conduit that is HDPE or equivalent. The external encasement must allow for the addition of at least one internal conduit and for the removal or replacement of internal conduits, as needed. The reamed bore size may not exceed 40 percent of the outside diameter of the external encasement, and a reamer that allows the natural wet grout to remain shall be used.(5) Installation. Longitudinal communication lines may be placed by plowing or open trench method and shall be located on uniform alignment with the right of way and as near as practical to the right of way line to provide space for possible future highway construction and for possible future utility installations. Attached Graphic
(6) Multiple conduits.(A) Shared conduits. When an existing utility rents, leases, or sells conduit usage to another utility, the utilities must jointly submit a use and occupancy agreement before placement of a new line within the conduit. A department permit is required before the installation.(B) Additional conduits. No more than two additional empty conduits may be added for every full conduit line, unless otherwise approved by the district.(C) All new conduits installed in the department's right of way shall be labeled with utility name and phone number at each point of access.(7) Aboveground appurtenances. (A) Aboveground pedestals or other utility appurtenances installed as a part of an underground communication line shall be located at or near the right of way line, so as not to impede highway maintenance or operations.(B) Hand holes may be installed at or below grade within five feet of the department's right of way line but only when sufficient width is available between curbs, sidewalks, and the right of way line. Their length may not exceed six feet and width may not exceed five feet. The cover must be rated for loads appropriate to the given location. Hand holes may not be installed in a sidewalk.(C) Large equipment housings. Structures that have a diameter larger than 18 inches may be placed on the right of way if: (i) the installation does not hinder highway maintenance operations;(ii) the housing is placed at or near the right of way line;(iii) the installation does not reduce visibility and sight distance of the traveling public;(iv) the dimensions of the housing are minimized, particularly where the need to allow space for highway improvement and accommodation of other utility facilities is apparent;(v) outside width, length (longitudinal), and height dimensions of the aboveground portion of the housing do not exceed 36 inches, 60 inches, and 54 inches, respectively;(vi) the supporting slab does not project further than three inches above ground line, nor extend further than 12 inches on either side of the housing structure; and(vii) the installation is compatible with adjacent land uses.(8) Abandonment. Underground communication lines may not be abandoned in place and shall be removed when no longer in use, unless the abandonment in place is authorized by the district. Encasements may be abandoned in place at the discretion of the district.43 Tex. Admin. Code § 21.40
The provisions of this §21.40 adopted to be effective March 17, 2005, 30 TexReg 1455; amended to be effective December 11, 2008, 33 TexReg 10064; amended by Texas Register, Volume 39, Number 40, October 3, 2014, TexReg 7949, eff. 10/12/2014; Amended by Texas Register, Volume 47, Number 40, October 7, 2022, TexReg 6622, eff. 10/12/2022