3.12 Utilities

Last Updated: 6-9-2017Print page

utilities

One of the important functions of the right-of-way is to provide space for water, sewer, electricity, street lighting, traffic signals and other utilities, both above and beneath the street surface. There are standard locations for each utility in relation to roadway pavement, curbs, planting strips, and sidewalks, and there are requirements for utility clearances.

The following sections define the design criteria for utilities in the right-of-way:

Street Lighting
Street Drainage, Storm Drains and Sewers
Water Mains
Fire Station Area

In addition to these sections, the following design criteria apply for utility easements and relocation.

Design Criteria

Utility Easements

Need for utility easements: When public utilities for sewer, storm, or power facilities are constructed on private property, a utility easement will need to be granted to the City. These easements are needed to establish rights for the City including, but not limited to, construction, operation, and maintenance access as needed to own and operate the facility.

Easement width: The width of the required easements are governed by factors such as the type of utility, its depth, size or diameter, the equipment needed for maintenance, etc. Sewer, drainage, water, and solid waste easements are prepared by SPU Real Property Services. Minimum easement widths for sewers and storm drains are found in SPU Client Assistance Memo (CAM) 1180: Design Guidelines for Public Storm Drain Facilities. For water mains, the minimum easement width is 20 feet. These are minimums, and site constraints may warrant greater easement widths.

Approvals for easements: Note that all easements (acquisition, relinquishment, and readjustments) for City owned facilities require approval by the Seattle City Council. For utilities owned by other entities, the applicant must contact the owner to determine required approvals for easements.  Planning ahead and working with the City early is highly recommended in order to get all the legal documents signed and recorded in a timely manner before any work is permitted. Council action can take up to 18 months in some cases.

Pipe location within an easement: For individual water, sewer or storm mains, the pipe shall be located in the centerline of the easement. The standard pipe material within an easement is Ductile Iron Pipe (DIP). For certain site conditions and buildover scenarios, SPU may require restrained joint ductile iron pipe, inside a steel casing pipe. For such installations, SPU requires a 25 feet “pit easement” on either the up hill or down hill side of the casing for the event that the pipe and/or casing must be removed. No private connections shall be allowed within the limits of the casing pipe. Generally casing pipes should have a 5 feet minimum distance past the edge of the building in the event of a buildover.

The easement needs a legal description prepared by a licensed professional land surveyor in the state of Washington.

Sewer and storm drains within the same easement: The minimum separation between the sewer and storm drain shall be 7 feet. The width of the easement on one side or the other will depend on pipe size and influence lines between the pipe and the building foundations (if any).

Utility Relocation

Need for relocation: It may be necessary to relocate or adjust existing utilities to accommodate new street grades or to attain standard clearances when constructing street improvements. This may include street lighting, traffic signal facilities, water, sewer, and drainage mains and appurtenances. It also may be necessary to relocate curb ramps and bicycle facilities.

Site assessment: The applicant is responsible for obtaining and reviewing surveys and as-built plans, taking field measurements, and contacting the affected utilities to determine if relocation or adjustment is required and the associated costs. The cost of utility relocation and adjustment is the responsibility of the applicant. 
Relocated utilities as well as new utilities to serve the development site shall be shown on street improvement plans when street improvements are required.

Pole consolidation: When installing new utilities or relocating existing utilities, it is the standard practice of the City of Seattle to reduce the number of poles where possible by combining utilities on one pole.

Seattle City Light

Electrical facilities and driveways: If an existing power pole or underground vault is in the middle of the future driveway, the applicant will be required to pay SCL, in addition to providing SCL with sufficient lead time, to reconfigure or to relocate its electrical facilities to resolve the conflict(s).

Electrical service entry points: It is also beneficial, financially and schedule-wise, for the applicant to pay attention to the electrical service entry point for the new building relative to SCL’s facilities in the public right-of-way. The farther the service entry point from SCL’s facility, the more complicated, time consuming and costly the service installation will be.

Underground ordinance areas: Certain areas in the City have been designated as underground ordinance areas. There is still a fair amount of overhead electrical distribution facility in some of the recently declared underground ordinance areas. Regardless of whether the existing electrical distribution system in the underground ordinance areas are overhead or underground, the electrical services to developments in these areas are required to go underground. Please contact other overhead utilities such as telephone and cable television companies for their undergrounding requirements in these areas.

Easements: Occasionally, if the available space, or the lack of available space, precludes SCL from serving the building(s) directly from its system in the public right-of-way, easement(s) from the property owner(s) or their neighbor(s) may be required for placing a local distribution system. This may include (but is not limited to) poles, anchors, wires, vaults, handholes, or conduits on site.

Further guidance and contact information: The Requirements for Electrical Service Connection Manual is available as a service installation guide for homeowners and developers.

SCL and SDCI staff will work closely with you to accomplish appropriate clearances required for design, during construction and at final build-out. Communication and resolution of required clearances are critical to final design and construction approval of your proposal. Contact City Light Customer Engineering for more information regarding service requirements.

sewerinstallfairview

Water Mains

New water mains are subject to the approval of Seattle Public Utilities (SPU) Development Services Office.

Links to Standard Plans and Specifications

Standard Specification 1-07
Standard Specification 7-10.3(5)C
Standard Specification 7-11
Standard Specification 9-30
Standard Plan 030: Desirable Locations for Utilities (Residential Street)
Standard Plan Section 300: Watermain Appurtenances
Standard Plan 286a and 286b: Sewer and Water Spacing and Clearances
Standard Plan 330a and 330b: Water Main Thrust Blocking Vertical Fittings

Design Criteria

Water main design: SPU Project Delivery & Engineering Branch (PDEB) provides design criteria for water mains during SIP design guidance.

SPU reviews water system designs through the street improvement process.  SPU also reviews proposed work within the right-of-way that may impact existing water mains or water facilities.

Protection of existing facilities: special measures to protect existing or proposed facilities may be required depending on the scope and impact of the proposed water main project. Special protection measures may include the use of restrained joint pipe, corrosion protection, and construction methods that minimize vibration and impacts of excavation to existing utilities.

Pipe material: All materials for water distribution shall be new and conform to Standard Specifications Section 9-30.

Standard location for water mains within the public right-of-way: Water mains will be generally located on the north and east side of the public right-of-way.  In the event that the standard location for water mains is not available the best alignment will be determined during SIP design guidance.

Water valves: Water valves will generally be placed aligned with the perpendicular right-of-way margins, as shown in Figure 4-22: Typical Valve Location. If this location is otherwise unavailable SPU PDEB will determine the alternative position. SPU will approve the final location for all water components constructed in the City right-of-way.

Water main, sewer and other utilities separation: Water mains and water service lines shall designed for appropriate separation from the following:

  • sanitary sewers
  • storm sewers
  • combined sewers
  • house sewer service connections
  • drains
  • sanitary sewer force mains
  • gas, telecommunications, electrical, and other utilities

Spacing between water mains and other utilities should comply with City of Seattle Standard Specifications 1-07, and Standard Plans 286a and 286b.

Depth of pipe cover: All pipe shall be laid to a minimum depth as indicated in Standard Specification 7-10.3(5)C and Standard Plan No. 030.

Thrust block: Provide concrete thrust blocks at points where piping changes directions or at dead ends. Thrust blocks shall be designed and installed as indicated in Standard Specification 7-11. Also, thrust blocks must conform to Standard Plan Nos. 330a and 330b.

For pipes larger than 12 inch diameter, or where water pressures are higher and/or soil conditions are poor, the developer engineer shall design the correct block size.  All thrust block designs will require the approval of SPU PDEB prior to installation. The stamped calculations shall be submitted to SPU PDEB for review and approval.

Test pressure for field testing water main pipe: Field pressure testing for water mains shall be in accordance with Standard Specification 7-11. 3(1).  Field hydrostatic testing of various diameter ductile iron water main pipes and appurtenances shall be:

Test Pressure for Field Testing Water Main Pipes

Diameter Pipe (inches)

4

6

8

10

12

16 or larger

Test Pressure (psi)

300

300

300

300

300

250

Flushing and disinfection: Before being placed in service all newly installed pipes, valves, hydrants and appurtenances shall be flushed, disinfected and kept clean, and an acceptable bacteriological report shall be obtained. Flushing and purification shall be in accordance with Standard Specification 7-11.

Vault location: Prior to water service approval, SPU Development Services Office shall coordinate all work associated with installation of service vaults. The table below provides some preliminary information. SPU Water Crews will perform all service work. Vaults shall be installed in the landscape/furniture zone.

Water services: For further inquiries regarding water services please contact SPU Project Delivery & Engineering Branch (PDEB) or www.seattle.gov/util/Services/Water/ObtainorUpgradeWaterService/index.asp

Vault Location by Meter Size and Type

Vault Meter Size and Type General Location in the ROW
Domestic
3/4″ & 1″ Domestic See City of Seattle Std. Plan #286b
1 1/2″ & 2″ Domestic See City of Seattle Std. Plan #286b
4″ Domestic Vault plan required. Installation by SPU Crews, contact SPU Development Services Office
6″ Domestic
Fire
2″ DC Fire Service Direct-bury in approved enclosure (meter box), standard pending.  Installation by SPU Development Services Office
4″-10″ x 3/4″ DC Fire Service
Combination 
4″ Combination Service Vault plan required. Installation by SPU Development Services Office
6″ Combination Service
8″ Combination Service

Design Considerations

  • Consider how to maintain fire flow during construction activities.
  • Coordination with SPU water operations is required for all new connections, services, meter installations and any temporary cut and caps or temporary mains to facilitate your construction.
  • Provide notice to the Fire Department if flow will be impeded and what provisions have been made – also note if access at the site will be limited or if street access will be limited.
  • Be sure to check for utilities in the project alignment especially around large service locations as they could interfere with water mains, blocking, or meter vault installations.
  • Only SPU crews are allowed to operate the existing water system for public health and safety reasons. Plan to coordinate with SPU water crews well in advance of starting construction to have your work added to crew work schedules.