Utility Coordination for GSI Projects
Santa Clara Valley Urban Runoff Pollution Prevention Program (SCVURPPP) GSI Handbook Part 2 Workshop #1
April 10, 2018Jocelyn Walker, PE, EOA Inc.
Objectives• Types of Utilities and Related Issues• Approach to Utility Coordination• Utility Issues in Various Project Phases
• Preliminary/Conceptual Design• Engineering Design• Construction
• Post Construction Issues• Round Table Discussion
Utilities in the Public Right of Way• Electrical Power lines (underground or overhead)• Gas distribution• Potable water distribution• Recycled water distribution• Sewer mains and service laterals• Communication and fiber‐optic lines• Vaults and valves• Streetlights• Traffic signal loops• Fire hydrants• Joint trenches
Underground Gas and Electric Facilities• Gas lines in Santa Clara County are owned and operated by municipalities or a private company.
• Safety concerns drive construction activities.• Utilities may require utility personnel to be onsite for inspection and oversight during construction if close to large gas transmission and high voltage power lines.
Overhead Electrical
• Pole location generally fixed• Poles may be used for multiple utilities• Clearance for construction• Clearance for O&M• Utility undergrounding/Rule 20A Projects may present an opportunity for incorporating GSI.
Example: PG&E Greenbookpge.com/greenbook
Guidelines for PG&E lateral protection under paving:7. PG&E must approve all requests for gas service in a casing before
installation. Provide and install an approved casing (i.e., sleeve) under the paving material when the paving will extend over the gas service lateral. Applicants must ensure that:
PG&E Greenbook Utility Separation
Potable Water
• Water distribution systems may be operated by the municipality or a private water company and may have varying rules and regulations.
• Potable water is pressurized and can be rerouted if necessary.
• Presence of a water line allows for irrigation.
Fire Hydrants• Contact the Fire Department at the beginning of the project if a hydrant is located nearby
• Relocation• Access for emergencies• Fire truck turning radius
• Avoid locating a hydrant within a GSI facility if possible
• Clearance and access may depend on the municipality
Example of Fire Department Requirement
Recycled Water• Utilities are implementing recycled water distribution networks.
• Future recycled water projects may provide an opportunity to combine opportunities to add GSI projects.
• Recycled water may be available for irrigation.
South Bay Water Recycling Strategic and Master Planning Report, SCVWD/City of San Jose
Sanitary Sewer• Sanitary Sewers are generally operated by a municipal agency or district.
• Most sanitary sewer systems are gravity systems and cannot be relocated without major expense.
• Small grade changes can significantly change sewer characteristics and cause backups, overflows, or odor problems.
• Tree roots often find their way into sewer pipes and cause overflows.
• Sanitary sewer lines must not be above water or storm pipes.
• Sanitary sewer lines should be below a GSI facility. SFPUC allows for sleeving of sewer laterals within GSI.
Sanitary Sewer Operation, Maintenance and Repair• Cleanout locations should be considered. • Maintenance may require large equipment and hoses dragged through an area. (CCTV or Cleaning)
• Replacement may require trenching or a pit for trenchless construction.• Trenchless methods may displace surrounding soil and cause damage to facilities located too close to the sewer pipe.
Communication• Various Types of Facilities
• Cable TV• Fiberoptic• Telephone• Cell towers
• Conduits may be relocated or encased
CPUC General Order No. 128 Rules for Construction of Underground Electric Supply and Communication
Other Utilities• Street Lighting
• Ownership and maintenance of street lighting varies by jurisdiction
• Traffic Loops
Approach to Utility Coordination with GSI (The Four Step Program)
Step 1: Avoid
Step 2: Accept
Step 3: Mitigate
Step 4: Replace
Step 1: Avoid Utility Conflicts
• Siting to avoid utility conflicts• Location• Vertical or horizontal clearance
• Selecting an appropriate GSI measure• Size• Depth of excavation
• Sizing • Avoid utility vaults
Step 2: Accept and Incorporate the Utility in Design• Encase Utility: Utility owner should determine/approve how to encase the utility
• Sleeve/casing• Insulating wrap• Impervious waterstops• Utility trench dam – prevents flow along utility trenches
• Encase GSI Facility• Impermeable liners above the utility could solve the problem if the GSI facility is not meant to infiltrate
• Permeable pavement: Utilities should be under structural pavement section below sub‐base when possible. Engineer should determine whether utilities are sufficiently protected from vehicle loads.
Step 3: Mitigation• Design around the utility
• Shape of facility adjustment• Adjust laterally• Change in depth of GSI measure• Change in type of GSI measure
• Smaller facility may still meet sizing requirements per BASMAA guidance
SFPUC Utility Crossings Detail
Step 4: Utility Relocation and Replacement
• Start early • Work with utility to determine schedule• Costs may be substantial for utility relocations
• Sewer mains or laterals• Utility poles• Fiberoptic• High pressure gas transmission• High voltage electrical transmission
• Potential to share costs with utilities if replacement is needed
• Bioretention• Permeable Paver Crosswalk• Utility Relocation
Example: Southgate Project, City of Palo Alto
Utilities Strategy• Use of existing plans for utility identification
• Pothole for existing utilities prior to start of excavation to check depths of existing utility services.
• Underground Service Alert (USA).
• 12” Clearance for all utilities
Example: Southgate Project, City of Palo Alto (Cont’d)
Example: Southgate Project, City of Palo Alto (Cont’d)
• Gas ‐ City Gas Utility Department• Cable ‐ Cable Company• Water ‐ Contractor per direction of City Engineer • Electrical Conduits ‐ Contractor per direction of City Engineer • Electrical Cable ‐ City Electrical Crews
Example: Southgate Project, City of Palo Alto (Cont’d)
Consider Utilities During Each Project Phase• Conceptual Design• Engineering Design• Construction• Post Construction
Avoiding Utility Conflicts at the Conceptual Design LevelConceptual level GSI design and siting: • Field evaluations for identification of visible utilities
• Review internal data and underground maps
• Send data requests to utilities• Easement Identification• Franchise Agreements• Utility permits pulled in the area
Avoiding Utility Conflicts at the Engineering Design Level
• Potholing• Include identified utilities on plans• Avoid utilities as much as possible• USA North Design Inquiry• It will be up to the design engineer to have a firm grasp on the requirements of various utilities when either moving or protecting a utility in place.
• Some utilities may require a letter from the owner rather than the designer regarding design inquiries.
• Utility trenches may include compacted backfill reducing infiltration rates.
Avoiding Utility Conflicts During Construction• Call 811• Potholing• Unknown Utilities • Laterals • Relocate or protect in place• Document changes in As‐Builts
Example: Park Avenue Green Street Pilot Project, City of San Jose
• AT&T fiberoptic conduit discovered during excavation
• AT&T did not respond to design request
• Not marked during USA marking• Solution was to encase conduit in concrete
Post Construction O&M and Repair• Consider access to utilities for maintenance activities
• Example: Utilities located on the sidewalk side of a bioretention area may require access from the street
• Standards for GSI facility replacement• Make sure to inspect repairs/rehabs of utilities under or next to GSI facilities
• Clarify who is responsible for restoring GSI features when incorporating utility into the design
Questions
Jocelyn Walker, PESCVURPPP/EOA Inc.(510) 832‐2852 x 119 [email protected]