17-229 C.M.R. ch. 210, § 10 - UNDERGROUND INSTALLATIONS

Current through 2022-14, April 6, 2022

1. General
A.Depth of Cover

The minimum depth of Cover for any Facility within the R/W limits is 36 inches, except for high pressure Hazardous Transmittant Facilities, (See Section 10(2)(A), Cover). Additional requirements are specified herein for each type of Facility.

Any wires, pipes, conduits or cables that are presently located within the Highway limits at a depth of less than 1 foot and not specifically permitted to be at that depth, shall be relocated in accordance with these rules.

B. Encasement

Casings shall be used under Bridge approach slabs and in close proximity to Highway Structure footings. Due to the wide variety of designs and the differing schedules for construction or maintenance, MaineDOT will need to determine Casing requirements near footings on a case-by-case basis. Where Encasement is to be employed in other areas, such Encasement shall be provided under center Medians and within the Pavement Structure limits to a point beyond the ditch line for cut sections, 5 feet beyond the toe of slope for fill sections, or 5 feet beyond the face of Curb on urban section roadways (including side streets). Exceptions for Encasement within a portion of the Median may be approved when excessive Median width or significant changes in the roadway cross-section make a continuous installation impractical.

C. Markers & Detection Aids
(1)Warning Tape

Upon installation, all underground Facilities installed by open cut shall include warning tape, of a color consistent with the APWA Uniform Color Code, located at least 12 inches below the ground surface, but no closer than 18 inches to the top of the Facility, and parallel to the entire installation.

(2) Signs

All underground utilities crossing the entire Right-of-Way (from one boundary to the other) shall have a readily identifiable marker installed at each Right-of-Way line crossed to indicate the type of Facility, the name of the owner and a telephone number to call. Signs shall be maintained with current, legible information.

(3) Pedestals

All pedestals shall have a readily identifiable marker installed on each pedestal to indicate the type of Facility, the name of the owner and a telephone number to call. Markers shall be maintained with current, legible information.

(4) Detection Aids

All nonmetallic underground Facility installations shall include a metallic component that provides electrical continuity to aid in the future detection and location of the Facility. When a separate tracer wire is used for this purpose, it shall be installed a maximum of 12 inches above the top of the Facility.

D. Appurtenances

Aboveground Appurtenances installed as a part of an underground Facility shall be located in accordance with Section 11, Aboveground Installations.

E. Methods of Installation
(1) Trenchless Installation Methods

All pits associated with Trenchless Installation Methods shall be located as far from the ETW as possible, preferably outside the Clear Zone. Pits shall be located and constructed so as not to compromise public safety or the integrity of any Highway Structure. The bottom of the pit sidewall nearest the roadway edge shall, at a minimum, be located beyond a line created by a 1:1 slope projected down from the Edge of Shoulder. The Region Engineer may require the use of support structures to achieve the proper degree of protection.

All trenchless installation methods are required to have the ability to accurately determine the horizontal and vertical position of the tip instrument when utilities, including drainage structures, are being crossed during installation.

(2) Blasting

48 hours' notice must be given to the appropriate MaineDOT Region Office prior to any blasting within the Highway limits. When blasting is to occur within 100 feet of a Highway Structure, prior approval must specifically be obtained from MaineDOT. MaineDOT may require that detailed plans and procedures prepared by a licensed blaster be submitted by the Authorized Entity. Pre-blast surveys may also be specified as a work condition.

(3) Pavement Cuts

Wherever pavement is to be cut, all edges shall be cut neat and straight.

(4) Backfill/Compaction

Backfill compaction shall equal that of the surrounding soil outside of the Pavement Structure limits. Within the Pavement Structure limits, Backfill and compaction requirements shall be in accordance with the latest edition of MaineDOT's Standard Specifications for Highways and Bridges.

F. Locations of Installations
(1)Undesirable Locations

Locations in deep cuts, near footings of Bridges or retaining walls, within areas of Special Materials, across intersections at grade, across ramp terminals, or in areas where it will be difficult to attain minimum Cover shall be avoided whenever possible.

(2) Clearance from Highway Structures

Vertical and horizontal clearance between any Facility or Appurtenance and a Highway Structure shall be sufficient to permit maintenance of both without interference. Clearances shall comply with Section 9(1)(I), Clearance Between Facilities.

(3) Road Side of the Utility Pole Line

Mainline underground Facilities should normally be installed on the Traveled Way side of the pole line.

(4) Additional Requirements

The location of any Facilities or Appurtenances may be further restricted by the Region Engineer to ensure that a proposed Facility or Appurtenance will not interfere with existing or currently planned Highway construction and/or maintenance activities.

(5) Highway Drainage Pipes

Highway drainage pipes and structures shall be protected during any Facility and Appurtenance installation and maintenance. Utilization of existing drainage pipes as Sleeves is not permitted.

(6) Services to Corner Properties

Property having frontage on both a state or state-aid Highway and a lower classification Public Way shall normally have the underground service provided from the lower classification corridor, whenever both corridors are served by equivalent distribution facilities. On a case-by-case basis, MaineDOT will consider the level of impacts to both corridors and to private property when determining the most appropriate point of connection. Should the lower classification corridor be under municipal jurisdiction, the Utility shall obtain the necessary permits from that municipality.

(7) Service Consolidation

In locations where numerous underground service lines must cross the Traveled Way, consolidation of service crossings shall be evaluated and utilized whenever possible. MaineDOT may require such consolidation whenever it is determined that impacts on the traveling public, highway maintenance or other accommodated Facilities will be minimized.

2. Gas, Liquid Petroleum, and Other Hazardous Transmittant Pipelines
A. Cover

Low pressure Hazardous Transmittant pipelines shall have a minimum Cover of 36 inches, including Service connection top tap tees and lines. Low pressure Hazardous Transmittant Facilities are defined as lines with working pressure of 100 psi or less.

The minimum depth of Cover for any portion of a high pressure Hazardous Transmittant Facility is 48 inches. High pressure Hazardous Transmittant Facilities are defined as lines with working pressure greater than 100 psi.

B. Multiple Lines

If a Utility proposes to install two active Hazardous Transmittant pipelines (typically transmission and distribution) along the same corridor, the two lines shall be placed one above the other, as vertical as practicable, considering safe operation and maintenance of the lines. The lower-pressure line shall be installed above the higher-pressure line and must meet the minimum cover requirements as specified in Section 10(2)(A), Cover.

C. Vents

One or more Vents shall be provided for each Casing or series of Casing. For Casing longer than 150 feet, Vents shall be provided at both ends. On shorter Casing, 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. Ownership of the lines and an emergency contact number shall be shown on the Vents.

D. Drains

Drains for Hazardous Transmittant pipelines will not be permitted to outfall into drainage ditches, natural watercourses or onto the Highway.

E. Gate Valve Boxes

When gate valve boxes occur within the paved portion of the roadway, they shall meet the requirements of ASTM A48 and shall be set flush with the pavement.Ref. Appendix - Standard Detail 604(18), Utility Structures

3. Water Lines
A. Cover

The minimum Cover for waterlines shall be 36 inches. The Authorized Entity is responsible to assure that all waterlines are suitably protected against freezing. All uninsulated water lines shall have sufficient Cover to exceed the depth of frost penetration.

B. Drains

Waterline Encasement or drains may be permitted to outfall into roadside ditches at locations approved by MaineDOT.

C. Gate Valve Boxes

When gate valve boxes occur within the paved portion of the roadway, they shall meet the requirements of ASTM A48 and shall be set flush with the pavement.Ref. Appendix - Standard Detail 604(18), Utility Structures

4. Sanitary Sewer Lines

Reference "Water Lines", Section 10(3)(A), Cover.

B. Drains

Sanitary sewer line Encasement drains shall not outfall into drainage ditches, natural watercourses, or onto the Highway.

C. Manholes

Manholes serving sewer lines up to 24 inches in diameter shall have a minimum inside diameter of 48 inches. For any increase in line size or number of pipes, the inside diameter of the manhole may be increased a like amount. Manholes for large interceptor sewers should be specially designed, keeping the overall dimensions to a minimum. The outside diameter of the manhole chimney at the ground level shall not exceed 36 inches. Any manholes allowed within the pavement shall be set flush with the pavement and will not be in the vehicular wheel path.

5. Electric Supply Lines

The minimum Cover for underground Electric Supply Lines and Services within the Highway limits shall be 36 inches.

B. Conduit

All underground Electric Supply Lines within the Highway Right-Of-Way limits shall be in galvanized or stainless steel Rigid Metal Conduit (RMC) or PVC Conduit. Electrical Metal Tubing and /or Intermediate Metal Conduit will not be permitted as substitutes for RMC. In addition, 90 degree RMC sweeps will be required.

PVC Conduit shall been cased, above, below and on both sides, with a minimum of 4 inches of concrete that shall have a minimum compressive strength of 2900 psi and a maximum aggregate size of 1-inch. Ref. Appendix - Underground Electric Lines Detail

C. Services

Electric Supply Line Services attached to a utility pole shall be installed in RMC from the ground level to a height of at least 7 feet and include a 90 degree RMC sweep below grade.Ref. Appendix - Underground Electric Lines Detail

Underground Electric Supply Line Services are not allowed to cross under the travel surface of the Highway and shall exit the R/W perpendicular to the centerline of the Highway. Ref. Appendix - Underground Electric Lines Detail

D. Manholes

Manholes shall be limited to those necessary for installation and maintenance of underground lines. The elevation of manhole rims and covers shall be set at finished grade (Ref. Appendix - Standard Detail 604(18), Utility Structures).New manholes will not be permitted within the Traveled Way or Shoulder of a Highway except within urban areas.

To conserve space within the Right-of-Way for the needs of the Highway corridor, manhole vault dimensions should be no larger than is necessary to hold the equipment involved and for safety standards to be assured for maintenance personnel. Outside width should not exceed 7 feet, with the length held to a reasonable minimum. The outside dimensions of a manhole chimney should not exceed the minimum required to support the manhole frame and cover. Manhole covers (for personnel access) shall be installed flush with finished grade and shall not be in the vehicular wheel path. The top of the roof of the manhole vault shall be set to meet a minimum Cover of 36 inches.

6. Communication Lines (Telephone, CATV, etc...)

The minimum Cover for underground Communication Lines within the Highway limits shall be 36 inches for either encased or un-encased installations.

B. Manholes

Section 10(5)(D), Manholes, applies.


17-229 C.M.R. ch. 210, § 10

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