Division 13-09-001
Underground Utilities

Sections:

13-09-001    Underground Utilities

13-09-001-0001    Underground Utilities

13-09-001-0002    Tracer Wires and Warning Tapes for Water, Reclaimed Wastewater and Sewer

13-09-001-0003    Water Main Depths and Separation

13-09-001-0004    Sewer Main Depths and Separation

13-09-001-0005    Separation from Storm Drains and Culverts

13-09-001-0006    Separation from Other Utilities

13-09-001-0007    Pipe Crossing of Existing Pavement

13-09-001-0008    Utility Alignment and Easement Requirements

13-09-001 Underground Utilities

Typical locations of utilities in streets are shown in Engineering Detail 9-01-010. Water, reclaimed wastewater, storm drain and sewer mains should be located in the paved roadway section (minimum four (4) feet from outside of pipe to lip of curb) far enough from the curb and gutter to allow backhoe access for maintenance without disturbing existing curb and gutter. Where possible, water shall be ten (10) feet north or east of centerline and sewer on the centerline. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-09-001-0001 Underground Utilities

A.    Utilities within easements must be located to minimize interference with one another, to provide required horizontal and vertical separations, and, to provide maintenance access without violating easement boundaries.

B.    For utilities located outside standard locations (such as common trenches with City utilities and public utility easements as shown on the approved plans), all franchise utilities, including power, gas, telephone, and cable, shall submit, or cause to be submitted, concept construction plans depicting the utility location(s), for review and approval prior to start of construction by the public improvement contractor.

C.    Regarding the City of Flagstaff approval, consideration shall include, but not be limited to, maintenance concerns, resource and slope protection, floodplain concerns, impact to public facilities, intersection sight triangles (clear view zones) and utility location. The City of Flagstaff may require utility relocation as the result of these considerations. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-09-001-0002 Tracer Wires and Warning Tapes for Water, Reclaimed Wastewater and Sewer

A.    A tracer wire shall be installed on all water, sewer, and reclaimed wastewater mains. Additionally, tracer wire shall be installed on all sewer services, fire lines and water services (strip wire two (2) inches at termination).

B.    The tracer wire shall be taped to the top of water, sewer, and reclaimed wastewater mains with ten (10) mil tape and shall be plastic covered No. 12 AWG type UF 600V. Plastic cover for tracer wires shall be blue for water lines, green for sewer lines, and purple for reclaimed wastewater lines.

C.    An approved type, five (5) pound magnesium anode shall be installed for each one thousand (1,000) linear feet of tracer wire or at least one (1) anode at each end of the project.

1.    The anodes for water line tracer wires shall be installed near the curb and next to a water service, (but at a minimum of one (1) foot apart) and in a separate cast iron valve box.

2.    The anode shall be placed at a tracer wire connection station under the valve box.

3.    The anodes for reclaimed wastewater tracer wires shall be installed inside the curb and on the south or west side of the pipeline.

D.    A tracer wire connection station shall be installed at each fire hydrant, street intersection, and one (1) station for each five hundred (500) linear feet of water, sewer, and reclaimed wastewater main, and at each end of the project (located on the same side of the street).

1.    For water lines at an intersection, the tracer wire shall be installed with a water service or fire hydrant run and set in a cast iron valve box next to the fire hydrant.

2.    No tracer wires shall be wrapped around a fire hydrant barrel.

3.    Tracer wire stations for sewers shall be located in conjunction with sewer services.

4.    For reclaimed wastewater lines at an intersection, the tracer wire shall be spliced into the main tracer wire and run to a cast iron valve box or located on the southwest corner of the intersection.

5.    For long lengths of water main without intersections the connection station shall be installed with a water service every five hundred (500) feet to the north or east side of the water line.

6.    For long lengths of reclaimed wastewater main without intersections, the connection station shall be installed to a valve box every five hundred (500) feet on the south or west side of the reclaimed wastewater line.

7.    Eight (8) feet of tracer wire shall be loosely coiled inside a separate cast iron valve box top section without a valve.

E.    The City Inspector shall observe the tests of all tracer wire performed by the installer or their agent prior to paving and acceptance by the City to show that all water/sewer/reclaimed wastewater mains and services can be located by this means. These tests shall be witnessed by the City Inspector.

F.    The City Inspector shall be provided all information necessary to "as-built" the location of all tracer wire, anodes, and connection stations.

G.    All tracer wire splices shall be carefully soldered and wrapped. Wires are to be wrapped with Scotch 3M electrical tape and inserted into a direct burial splice, use Scotch 3M DBR-6 or equivalent.

H.    The tracer wire, anodes, and connection stations shall be detailed on the water main, sewer main, and reclaimed wastewater main construction plans.

I.    A six (6) inch wide plastic warning tape, twelve (12) inches to twenty-four (24) inches below finished grade, shall be installed above all water, reclaimed wastewater and sewer mains.

1.    The plastic warning tape for water mains shall be blue, green for sewer lines, and purple for reclaimed wastewater lines.

2.    The tape shall be permanently printed at least every thirty-six (36) inches with "BURIED WATER LINE BELOW" for water mains, "BURIED RECLAIMED WASTEWATER LINE BELOW" for reclaimed wastewater mains, or "BURIED SEWER LINE BELOW" for sewer mains. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-09-001-0003 Water Main Depths and Separation

A.    Minimum cover is to be measured to subgrade unless there is no pavement; then it is measured to finished grade.

1.    Water lines shall have a minimum cover to subgrade of three (3) feet over the top of the pipe as shown in Engineering Detail 9-01-010.

2.    Water lines shall have a maximum depth of six (6) feet, measured to top of pipe, unless approved by the City Engineer. Exceptions to this include vertical realignments to avoid other utilities.

3.    To minimize the potential for cross contamination, water and sewer mains shall not be located closer than six (6) feet horizontally and two (2) feet vertically as described in AAC R18-4-502 and illustrated in MAG Standard Detail No. 404-1 with the following supplemental requirements:

a.    When a water main is below a sewer main, the minimum separation is two (2) feet and extra protection is always required in accordance with MAG Specifications.

b.    When a water main is above a sewer main, extra protection is required when the water main is closer than two (2) feet to the sewer main.

4.    A one (1) foot minimum vertical separation shall be provided between a storm drain crossing a water main. The minimum vertical separation is measured from outside of water main to outside of storm drain. Extra protection is required in accordance with MAG Specifications when these requirements are not met.

5.    A six (6) foot minimum horizontal separation shall be provided between a sewer main or storm drain and a water main. The minimum horizontal separation is measured from outside of pipe to outside of pipe.

6.    Whenever two (2) parallel water mains are required, there shall be a six (6) foot minimum horizontal separation between the two (2) mains to allow for tapping, tie-over, and maintenance.

7.    A three (3) foot minimum horizontal separation shall be provided between a fire hydrant and any water service line.

B.    Reclaimed wastewater mains shall be considered the same as water mains for the purpose of minimum cover and separation. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-09-001-0004 Sewer Main Depths and Separation

A.    Minimum cover is to be measured to subgrade unless there is no pavement; then it is measured to finished grade. In all cases, sewer lines are to be at a depth sufficient to provide gravity service to all adjacent building pads. Service lines are to be laid at grades and depths prescribed in the International Plumbing Code, which has been adopted by the City. Vertical and horizontal separations of water and sewer shall conform to A.R.S. requirements and in accordance with ADEQ requirements.

1.    Sewer line shall have a minimum cover of four (4) feet over the top of the pipe as shown in Engineering Detail 9-01-010.

2.    Sewer lines shall have a maximum depth of twenty-five (25) feet, measured to bottom of pipe invert.

3.    Vertical clearance between water mains and sewer service connections: the water main shall not be less than six (6) inches above the sewer service even if the sewer service connection is constructed with ductile iron pipe in accordance with MAG Standard Detail 404-1.

When the sewer service is above the water main, minimum clearance shall be one (1) foot. The sewer service connection must be constructed with PVC SDR 35 or ductile iron Class 350 SVC pipe with minimum one (1) foot of separation with no pipe joints within six (6) feet of pipe. Alternate is to install in accordance with MAG Standard Detail 404-1. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-09-001-0005 Separation from Storm Drains and Culverts

Water and sewer mains shall maintain six (6) feet horizontal and one (1) foot vertical separation from storm drains and culverts. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-09-001-0006 Separation from Other Utilities

Water and sewer mains shall be separated from other utilities in accordance with Engineering Detail 9-01-010 for joint trench utilities. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-09-001-0007 Pipe Crossing of Existing Pavement

Pavement replacement for crossings on existing paved streets shall be as described in the typical trench details. Crossing of Federal, State, or County highways will be in accordance with specific requirements of the controlling agency. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-09-001-0008 Utility Alignment and Easement Requirements

A.    The City of Flagstaff Utilities Division requires safe and quick access to all City water and sewer mains at all times in order to repair main breaks, install taps, and perform preventive maintenance. For this reason, City of Flagstaff water and sewer mains shall be constructed in streets within the public right-of-way. Where possible, water shall be ten (10) feet north or east of centerline and sewer on the centerline. Water mains in easements create access problems and will not be permitted except under the following special circumstances.

B.    Easements will only be considered in the following cases:

1.    For a short segment of main where it is not technically feasible to design the utility mains in the right-of-way without violating City codes or ordinances and that, in the opinion of the Utilities Division, the proposed alignment of the water or sewer main in an easement results in more efficient operation of the utility system.

2.    The project route is in conflict with other utilities, a wash, or drainage corridor.

C.    Minimum easement widths:

1.    For one (1) utility main, the minimum easement width shall be twenty (20) feet in width.

2.    For two (2) utility mains, the minimum easement width shall be twenty-six (26) feet.

3.    When a water service or fire hydrant is located adjacent, but outside of, the right-of-way or public utility easement (PUE), a PUE shall be extended to accommodate the appurtenance. The minimum dimensions of the PUE shall allow for three (3) feet of clearance from all sides of the appurtenance.

D.    In addition to the above, all appurtenances (e.g., blow-offs and hydrants) shall be provided with an easement dimensioned to provide a minimum of three (3) feet of clearance on all sides of the utility.

E.    Easement widths may be increased to accommodate the required construction and maintenance activities, particularly where utility lines are deeper or larger than normal. Sewer and water mains shall be centered within the easement and separated by six (6) feet when there are both.

F.    When a water or sewer main is located adjacent to a building, the main shall be offset a minimum of ten (10) feet from the building in a minimum twenty (20) foot easement.

G.    Public utility, sewer, and water easements shall be free of all permanent obstructions and shall comply with Division 13-04-001.

H.    For sewer or water easements not located within a public street, an all-weather access road is required if manholes, valves, fire hydrants, or other appurtenances requiring City access lie within the easement. The access road shall have a minimum width of ten (10) feet and shall be constructed in accordance with the structural section in Standard Detail No. 14-02-002. For those access roads not dedicated as FUTS trails, the aggregate surface course shall be replaced by a full-depth ABC section. The access road shall connect to a public or private road. (Ord. 2017-22, Rep&ReEn, 07/05/2017; Ord. 2024-13, Amended, 4/16/2024 (Res. 2024-15))