COUNTY OF SAN MATEO

Inter-Departmental Correspondence

Department of Public Works

 

DATE:

August 6, 2004

BOARD MEETING DATE:

August 31, 2004

 

TO:

Honorable Board of Supervisors

FROM:

Neil R. Cullen, Director of Public Works

SUBJECT:

Increase in Contract Authorization – Colma Creek Channel Improvements – Spruce Avenue to San Mateo Avenue – South San Francisco

 

Recommendation

Acting as the governing board of the San Mateo County Flood Control District, adopt a resolution authorizing an increase of $2,100,000 in the “Not-To-Exceed” payment limit for contract costs for the Colma Creek Channel Improvements Project (Project) between Spruce and San Mateo Avenues.

 

Previous Board Action

*

Authorized the sale of certificates of participation to help finance flood control improvements in Colma Creek.

   

*

Awarded a contract for the Project to Northwest Construction on June 27, 2003.

 

Key Facts

1.

The original contract had a "Not-To-Exceed" limit of $12,091,000 ($10,991,327 low bid plus $1,099,673 in contingencies), which normally would cover all contract costs including differences in final contract quantities as compared to estimated quantities, and any extra work usually associated with this type of project.

 

2.

We believe the Not-To-Exceed limit will be substantially exceeded as a result of the extent of contaminants found in the materials to be removed from Colma Creek in conjunction with the Project.

 

Discussion

Approximately 40,300 cubic yards of material needs to be removed from the creek channel within the Project limits to facilitate construction of flood control improvements. This material has to be disposed of as required by various federal and state agencies which evaluate the material on its potential impact on water quality. These agencies are also involved in designating the landfills that can accept these wastes based on the level of protection to water quality that the landfills provide. The following is a summary of the material categories and the class of landfills that can accept these materials:

 
 

Material Designation

Regulatory Agency Classifying Waste

Type of Landfill that can accept Designated Wastes

 
         
 

Hazardous Waste

USEPA*
DTSC*

Class 1

 
         
 

Designated Waste

DTSC*
SWRCB*

Class 2

 
         
 

Non-Hazardous Waste/Garbage/Treated Medical Waste

SWRCB*
DHS*

Class 3

 
         
 

Inert Material

SWRCB*

Unclassified Landfill

 
 

Notes:

*

USEPA - Unites States Environmental Protection Agency

   

DTSC - State Department of Toxic Substances Control

   

SWRCB - State Water Resources Control Board

   

DHS - Department of Health Services

 

Soil samples were taken as part of the design phase of the Project and estimates made on the level of contamination and the amount of soils that would need to be disposed of at the different classes of landfills. This information was used to develop contract bid items for the work. Additional samples were also taken once the work began, and the level of contaminants and the amount of contaminated material substantially differed from the estimates that were based on the original samples.

 

The primary contaminant is lead, and there was a battery recycling business adjacent to Colma Creek that may have been the source of the lead contamination. We also believe that the contaminants may have migrated up and down the Creek as this section of the Creek is subject to tidal action. The following is a summary of the amount of material that has to be disposed of at the various class of landfills, based on the original contaminant levels and on those found during the most recent soil sampling:

 

Designated Landfill Class for Disposal of Material

Prior to Construction Estimate of Cubic Yards of Material to be Disposed of by Landfill Class

Current Estimate of Cubic Yards of Material to be Disposed of by Landfill Class

 

Cubic Yard

Increase or (Decrease)

Estimated Increase or (Decrease) in Costs

 
             

Class 1

3,000

7,100

*

4,100

$1,112,200

 

Class 2

0

26,000

 

26,000

$1,046,240

 

Class 3

6,200

3,600

 

(2,600)

$(54,600)

 

Unclassified Landfill

31,100

3,600

 

(27,500)

$0

**

Total

40,300

40,300

 

0

$2,103,840

 
 

*

Includes approximately 4,000 cubic yards that have to be pretreated before the material can be disposed of at a Class 1 disposal site.

 

**

No separate pay item for unclassified landfill disposal. Estimated cost increases are for the additional haul distance and the additional landfill costs.

 

The initial samples led us to believe that the majority of material could be disposed of locally, or incorporated into other construction where fill material is needed; and the Project’s contract documents did not include a bid item for the excavation, off-haul and disposal of Class 2 material, nor for Class 1 pretreated material. The estimated costs as shown above are based on increased haul and disposal costs for the reclassified material, as the closest Class 2 facility is located in Manteca and the closest Class 1 landfill in Kettlemen City. The tipping fees for the landfills range from $15.75/ton for Class 2 material to $137.50/ton for pretreated Class 1 material. The anticipated costs to handle this reclassified material is approximately $2,100,000.

 

We are also working with our environmental consultant, the City of South San Francisco and the County Environmental Health Division in order to ascertain whether there are alternatives to dispose of the material, such as encapsulating the material on nearby land, since we are removing the material from the creek channel where impacts to water quality are potentially greater than if the material was deposited in an upland location.

 

Vision Alignment

We believe our recommendation is consistent with the Shared Commitment to provide “responsive, effective and collaborative government” and with Goal Number 20 “government decisions are based on careful consideration of future impact, rather than temporary relief or immediate gain” as authorizing an increase in contract costs will allow for the improvements to be constructed as intended, and to appropriately dispose of material considered to have varying degrees of impact on water quality.

 

Fiscal Impact

The proposed changes will authorize an increase in the original "Not-To-Exceed" amount from $12,091,000 to $14,191,000. The actual costs will be based on final quantities of work for the project and on executed contract change orders.

 

Funds from the Colma Creek Flood Control Zone of the San Mateo County Flood Control District together with funds from the sale of Certificates of Participation by the Flood Control District will be used to finance this work.

 

There is no impact to the General Fund.

 

A form of resolution has been approved by County Counsel.