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P2009.000.164 BKF Engineers April 15, 2009 Levee Improvements Adjacent to the San Carlos Airport Latest Revision June 30, 2009 PROPOSAL FOR A GEOTECHNICAL EXPLORATION - PHASE 1 Page 2 Alert (USA) notifications. We have assumed that San Mateo County will waive their permit fee. We anticipate portions of our proposed scope will require notification for potential intrusions into FAA airspace safety zones but we have assumed no permit fee is necessary. In addition, we understand our proposed service may require notification of the United States Army Corps (Army Corps) and the Regional Water Quality Control Board (RWQCB). All field representatives and drilling subcontractors will undergo San Carlos Airport site-specific safety training prior to the commencement of the field exploration. All field work will be coordinated with the San Carlos Airport Manager at least 48 hours in advance. 2. We propose to advance five rotary wash soil borings through the crest of the existing levee. Three of the five proposed borings will be drilled through the crest of the existing San Carlos Airport levee (within the County of San Mateo) while the remaining two proposed borings will be advanced through the crest of the existing encroaching portions of levees within the City of Redwood City and City of San Carlos. Each of the proposed exploration locations will extend approximately 10 feet into fum soils, which we anticipate will be approximately 40 to 50 feet below existing grades. In addition, five additional borings will be drilled at select locations for in-situ Vane Shear Testing (VST). The borings will be completed using a truck-mounted drill rig from the crest of the existing levee system(s). Borings will be backfilled on the day of drilling following County requirements comprising neat cement grout. Figure 1 shows the approximate locations of the proposed soil borings and Vane Shear Tests. 3. During the subsurface exploration, an ENGEO geologist or engineer will observe the sampling operations and log the samples recovered. Soil samples will be recovered at frequent intervals for visual classification and laboratory testing. Soil samples will be collected by driving or pushing split-spoon (California type or Standard Penetration Test) or Shelby tube samplers, respectively, at locations selected in coordination with the design team. These samples will be used to determine strength and consolidation properties of the soil deposits. In addition, in-situ Vane Shear Testing will be performed in additional borings at select locations adjacent to the proposed soil boring locations. The Vane Shear Testing will be performed in the Young Bay Mud deposits to assess in-place shear strength of the soft deposits anticipated below the levees. SCHEDULE We expect that our permitting and scheduling services will commence immediately following your authorization and receipt of an agreement. The exploration will require permitting with the County of San Mateo and notification of the Army Corps and RWCQB, as necessary. We understand the County requests a minimum of 5 working days to process a drilling permit. We will also submit FAA Form 7460-1 to notify the San Francisco Airports District Office of the planned soil boring and Vane Shear Test within the FAA safety area. We understand the San Carlos Airport must be closed during the drilling of the proposed boring and Vane Shear Test within the FAA safety area; therefore, we have assumed that these explorations will be performed at night (after 9:00 PM and before 6:00 AM). This includes