COUNTY OF SAN MATEO

Inter-Departmental Correspondence

Department of Public Works

DATE:

December 13, 2002

BOARD MEETING DATE:

January 7, 2003

TO:

Honorable Board of Supervisors

FROM:

Neil R. Cullen, Director of Public Works

SUBJECT:

Increase in Contract Authorization for the El Camino Box Culvert Project - Colma Creek Flood Control Zone.

Recommendation

Acting as the governing board of the San Mateo County Flood Control District, adopt a resolution authorizing an increase of $300,000 in the "Not-To-Exceed" payment limit for contract costs for the El Camino Real Box Culvert Project.

Previous Board Action

Awarded a contract for the El Camino Real Box Culvert Project to Homer J. Olsen, Inc. on August 21, 2001.

Key Facts

1.

The original contract had a "not to exceed" limit of $10,500,000 ($9,744,955 low bid plus $755,045 in contingencies), which we believe would have covered changes in final contract quantities as compared to estimated quantities, as well as extra work normally associated with a flood control construction contract.

2.

We believe the not-to-exceed limit will be exceeded as a result of the need to perform extra work on the project due to additional traffic control work, conflicts with underground utilities, replacing unsuitable bedding and disposing of contaminated soil.

Discussion

The El Camino Box Culvert Project consists of constructing a box culvert along an approximate 1.25 mile length of El Camino Real from Mission Road in the Town of Colma to "A" and Valley Streets near Daly City in order reduce the potential for flooding from Colma Creek in this area. El Camino Real in this area is a major access route to the Colma BART Station and also provides access to several cemeteries in the Town. The work involves excavation of an approximate 15-foot-deep by 24-foot-wide trench to accommodate the new box culvert. Typically, underground work results in conflicts with existing utilities or other unforeseen work that occurs as the excavation proceeds.

The contract has provided a 7.7% contingency to provide for unforeseen work. However, we are anticipating extra work costs that may increase the total project costs by an additional $300,000 over the contract "Not to Exceed" amount, primarily as a result of the following extra work:

A.

An abandoned tank and contaminated soil were discovered while excavating to install portions of the box culvert. Testing of the soil indicated it was contaminated with benzenes and heavy metals. Some of the soil had to be taken to a waste disposal site in Manteca, California due to the level of contaminates, with the remainder disposed of at Ox Mountain. The estimated cost for this work is $450,000.

B.

A number of underground utilities either were not known to exist or were in conflict with the box culvert required relocation. These conflicts resulted in delays and remobilization costs as construction operations were moved from and then back to the areas where the conflicts occurred. The estimated cost of this work is $250,000.

C.

The necessary transition structures that connect the new box culvert to the existing drainage facilities had to be revised once the existing drainage facilities were exposed. These design changes required additional work as well as delays in the construction. The estimated costs for the associated work is $100,000.

D.

Additional traffic control work was necessary to provide safe access to the cemeteries and businesses within the construction area, as well as for traffic using El Camino Real. This necessitated placing a temporary portable signal system and additional striping and delineation. The additional cost for the traffic control is estimated to be $100,000.

E.

Ground water and unsuitable bedding material for the box culvert was encountered over a several hundred foot section of the work. It was necessary to excavate two feet of the unsuitable material and place drain rock. The estimated costs for this work is $50,000.

F.

We have also encountered a number of miscellaneous items that have required extra work. The estimated costs for this work is $100,000.

Vision Alignment

We believe our recommendation is consistent with the Shared Commitment to "ensure basic health and safety for all" and Goal Number 7 to "maintain and enhance the publicly safety of all residents and visitors" as the extra work associated with the project will improve the overall drainage system in the Colma Creek drainage basin and reduce the potential for flooding of private and public property.

Fiscal Impact

The proposed changes will authorize an increase in contingency for the project from $755,045 to $1,055,045 - or from 7.75% of the low bid to 10.8% of the low bid. The original "not-to-exceed" amount will increase from $10,500,000 to $10,800,000. The actual costs will be based on final quantities of work for the project and daily extra work reports associated with executed contract change orders.

The additional costs are proposed to be paid for with funds of the Colma Creek Flood Control Zone of the San Mateo County Flood Control District.

There is no impact to the General Fund.

A form of resolution has been approved of by County Counsel.

Other Claims

We also anticipate that the contractor may file additional claims at the end of the project. These claims will be the subject of negotiations with the contractor to determine their validity, and will be discussed with County Counsel before any proposed settlement is recommended. We will report to your Board on these claims if it is determined that additional contingencies are required.