In response to a tragic explosion during excavation work near downtown Walnut Creek in November 2004, State Senator Tom Torlakson introduced Senate Bill 1359 to make construction work around underground pipelines safer. The bill went into effect on January 1, 2007.

It imposes new obligations on parties involved in construction projects that require excavation near underground pipelines. 

The Walnut Creek accident was caused when a high pressure fuel line was struck by a backhoe during work on a new water main for the East Bay Municipal Utility District. Five workers were killed and four were injured.   It was later discovered that workers responsible for marking the pipeline’s location failed to mark a bend in the pipeline accurately. Field markings showed the pipeline running straight instead, which is a common problem according to some construction industry representatives. SB 1359 was passed with the hopes of reducing the risk of such incidents in the future.

New Requirements

SB 1359 creates a new category of “high priority” underground utilities and creates more stringent requirements that must be met when attempting to locate them. “High priority subsurface installations” are defined as: “high- pressure natural gas pipelines with normal operating pressures greater than 415kPA gauge (20psig) or greater than six inches nominal pipe diameter, petroleum pipelines, pressurized sewage pipelines, high-voltage electric supply lines, conductors, or cables that have a potential to ground of greater than or equal to 60 kv, or hazardous materials pipelines that are potentially hazardous to workers or the public if damaged.”  Once underground utility operators have been notified of plans to excavate within 10 feet of high priority subsurface installations, the operator of the facility must notify excavators of the existence of the installations before the start of the excavation. The operator and the excavator must then meet at the site of the excavation, before excavation is to begin, to determine the best way to confirm the location of the underground utility. In addition, operators of high priority subsurface installations are required by the new law to maintain and preserve all plans and records for their underground utilities. Previously, no distinction was made for “high priority” installations and no on-site meeting was required.

The bill also creates new requirements regarding who must determine the location of subsurface installations and how the installations should be located. This work must now be performed by state-approved “line-riders” who mark the location of dangerous pipelines. Operators of all subsurface installations who receive notification of any proposed excavation work are still required to locate and field mark or otherwise notify the excavator of the approximate location of subsurface installations that may be affected.  As before, once the approximate location of nearby underground utilities is field marked, excavators are left to determine their exact location using hand tools before using any power driven equipment. However, the bill now requires  a “qualified person” who has completed an injury prevention program and meets specified minimum guidelines to perform “subsurface installation locating activities.” The bill also specifies the best available technology to be used when locating pipelines.    

The new law will also impact when and how an excavator is to contact an underground utilities operator for help. As before, the law still requires excavators that cannot determine the exact location of utilities to ask the operator for more information to help locate it. However, regional notification centers must now provide excavators with the contact information of utilities operators when the excavator has difficulty determining the exact location of an installation. Also, excavators who discover or cause damage to an underground installation must now immediately notify the operator. Excavators can ask for the operator’s contact information from the regional notification center but if “high priority” subsurface installations are damaged and the operator cannot be reached, the excavator must call 911 emergency services. 

The bill does not change the existing requirement that entities owning, operating, or maintaining underground utilities must join a regional notification center, such as Underground Service Alert North or Underground Service Alert of Southern California, to provide warning of installations that are close to proposed excavation projects. Except in emergency situations, anyone planning to dig in an area with underground installations must provide notice to the appropriate center not less than two days before breaking ground if there is reason to believe that the area will contain underground installations that are not owned or operated by the excavator. Also, as before, if it is practical to do so, the entity planning to dig must also mark the area to be excavated in white paint.

New Exposure to Liability for Utility Operators

The new law increases potential exposure to liability for utility operators significantly. Owners of an underground utility will now be liable to an excavator that has complied with the law for any damages, costs and expenses that are caused by the operator’s failure to: field mark the locations of underground pipelines, notify an excavator of a “high priority” subsurface installation’s existence if it is near the proposed excavation site, or provide an excavator with additional information if the excavator cannot locate underground installations with hand tools.

The new bill does not affect claims brought against the excavator or operator by other parties for damages arising from the excavation. As under the old law, excavators that damage underground utilities must compensate the operator for the resulting damages, costs, and expenses to the extent that the damage was caused by the excavator’s failure to: notify a regional notification center of a proposed excavation or, determine the exact location of the subsurface installation with hand tools, or follow any special instructions given by the installation’s operator.


Senator Torlakson’s bill creates new safeguards to assure that underground utilities near construction excavation sites are located and properly marked. Greater assurances of safety on construction sites is certainly good news, but the requirements for identifying underground utilities and marking underground lines accurately will also create additional costs for construction projects. However, the Assembly Appropriations Committee concluded that the expense of training employees to qualify them to locate utilities would be minor and absorbable for any state agency controlling underground utilities, and that local agencies owning underground utilities and providing similar training for their employees could recoup the costs by charging user fees.