CONTRACTOR'S INQUIRY RESPONSES

April 21, 2003

CONTRACT NO. 04-0120C4
CONSTRUCT W2 FOUNDATION AND COLUMN
County Route: SF-80-8.2/8.2

 

The responses to contractors' inquiries, unless incorporated into a formal addenda to the contract, are not a part of the contract and are provided for the contractor's convenience only. In some instances, the question and answer may represent a summary of the matters discussed rather than a word-for-word recitation. The responses may be considered along with all other information furnished to prospective bidders for the purpose of bidding on the project. The availability or use of information provided in the responses to contractors' inquiries is not to be construed in any way as a waiver of the provisions of section 2-1.03 of the Standard Specifications or any other provision of the contract, the plans, Standard Specifications or Special Provisions, nor to excuse the contractor from full compliance with those contract requirements. Bidders are cautioned that subsequent responses or contract addenda may affect or vary a response previously given, and any such subsequent response or addenda should be taken into consideration when submitting a bid for the project. Inquiries submitted within seventy-two (72 ) hours of the bid opening date might not be addressed.

The Caltrans District 4 Office is located at 111 Grand Avenue, Oakland, CA 94612. Send Contractor Inquiries via email to the Duty Senior at Duty_Senior_TollBridge_District04@dot.ca.gov. The mailing address is P.O. Box 23660, Oakland, CA 94623-0660. The Toll Bridge Duty Senior's telephone number is (510) 286-5549 and the fax number is (510) 286-4563. All inquiries must include the contract number.

Total Number of Inquiries:34
Inquiry
No.
Inquiry/Response

1.0

We are concerned with the specified maximum temperature of 122°F for the footing. This is extremely low, especially due to the size of the footing and the specified concrete properties and constituents. Additionally, the specified maximum temperature is less than that of other smaller mass concrete placements on this project. The concrete mix design is specified to have 590 lb/cu yd of cement, with 40% replacement by fly ash (or 50% replacement by slag). The water-to-cement ratio is fixed at 0.4. With these concrete parameters, and the size of the footing, we find it extremely difficult and costly to meet this temperature limit even by placing concrete in lifts, or with extensive pre-cooling and post cooling with internal pipes. We request the maximum concrete temperature be increased to at least 149°F. This is more reasonable and is the limit used on other Bay area bridges.

The maximum temperature of 50 C (122 F) is specified to ensure that the footing concrete will not pull away excessively from the concrete rock interface as a result of thermal movement. Consequently, the maximum temperature is less than that specified for other Bay area bridges. The maximum concrete temperature of 50 C (122 F) is achievable.

2.0

Can we use SF-DODS 50 nautical miles west of Golden Gate Bridge or any other aquatic disposal site for the excavated footing material?

The material is not suitable for aquatic disposal.

3.0

Specification section 10-1.22 (page 143) prohibits any materials to be delivered or hauled off from the Island during the hours of 5:00 am – 10:00 am and 3:00 pm– 7:00 pm on weekdays, leaving a work window of only 6 hrs/day. Furthermore section 5-1.26 puts a limitation of noise levels to be within 78 dbA at 50 ft from the source. Most of the concrete pours on this contract will last more than 6 hrs/each and as a result most large pours will be made during nighttime. The noise generation from the concrete pouring operations will exit the 78-dbA-limit set forth in the specifications.

We request that the 78-dbA-limit should not apply for the concrete placing operations, especially since there are no facilities within close proximity of the project.

Furthermore, if the two requirements as stated above are not modified by the State, what is the State’s vision of the concrete placing operation on this contract?

Specifications 5-1.26 and 10-1.22 shall remain as stated in Special Provisions. If contractor's concrete pouring operations will exceed the 78dBA at 50 feet restriction between hours of 7:00pm and 7:00am, then contractor needs to propose appropriate mitigation measures at the noise source.

4.0

The 100 mm thick plate called out in Section K-K, Sheet 66 of 110, cannot be mill produced full size. Can that material be splices and if so, vertically or horizontally?

The 100 mm thick plate may be spliced vertically.

5.0

Under “Test Requirements” it states that 5% of the rods, couplers, and anchorages will be sampled and tested at a laboratory in the US. If the tests to be performed are destructive tests, do an additional 5% of the quantity need to be purchased? Does the Guaranteed Unit Price for the 144 each apply to this additional 5% or does the Total Guaranteed Price include the quantity of these test samples?

The Guaranteed Unit Price for the 144 each does not include an additional 5% for the destructive testing of the test specimens. The guaranteed unit price applies to the additional 5% test specimens provided the test specimens are the same length as the production bars. If longer or shorter test specimens are required the unit price may be adjusted up or down by the manufacturer. Contact the manufacturer directly for additional information.

6.0

Will a “rat slab”, of the same structural concrete as the footing mix, be allowed in the bottom of the excavation to support the lower tie-down base frame and to provide a uniform bearing surface for the footing and column cage rebar?

The use of a concrete binding layer, or rat slab, is acceptable provided its compressive strength meets or exceeds 35 MPa and its surface is roughened to a minimum amplitude of 5 mm.

7.0

Ref: BCDC Permit No. 8-01 Page 22 Section H. Temporary Access states, “The permittee is strictly prohibited from using solid fill in the Bay for construction access…with the exception of the minimum amounts necessary of earthen fill to create necessary grade transitions…”.

If the Contractor elects an earthen fill in order to access the barge at the “barge access” area will this work be covered by the existing BCDC permit?

The barge access area falls within the jurisdiction of the BCDC Permit. If the earthen fill is minimal, it may be acceptable to BCDC after it is reviewed by BCDC.

8.0

What is the States intent by providing the contractor a “barge access” area if the contract doesn’t allow land to barge access at this point?

The contractor may construct a pile-supported dock/pier to create the land to water access for the barges. If the Contractor elects to construct a pile-supported dock/pier, an amendment to the BCDC Permit will be required. In bay earthen fills will not be allowed as a means of land to water access.

9.0

The contractor needs information regarding the existing BayBridge pier that is adjacent to the new W2 south footing. The existing pier appears to be approximately 50 ft from the excavation for the new footing. In order to properly analyze an excavation support system we need the loading of the existing pier and the elevation of the bottom of this pier.

The existing pier adjacent to W2 is a spread footing with bottom of footing elevations of 15.70 meter (51.5') on North side and 3.05 meter (10.00') on South side. The net load at the base of the existing foundation is 24,834 metric tons.

10.0

Drawing U-1 shows a 75 mm water line on the north side of Pier W2E. Where is this paid for?

Attention is directed to section 19-1.04 of the Standard Specifications.

11.0

May a contractor excavate and/or grade access ramps to pier W-2W and W-2E providing they are restored to O.G. due to the area being designed as “environmental sensitive?”

No. Contractors cannot excavate or grade access ramps within environmentally sensitive areas.

12.0

Is it a correct assumption that blasting which meets the criteria outlined in the Special Provisions is allowed for all aspects of the structural excavation and rock sockets?

Blasting may be used for structure excavation. Blasting shall not be used to create rock sockets.

13.0

Due to the concrete temperature requirements of the specifications, it is not definite when the concrete will obtain a temperature that will allow the post cooling process to be discontinued and removed. When will Caltrans accept the project and not count working days? The post cooling may have to be continued for many months after the last concrete placement.

The Special Provisions require that the Contractor develop a Thermal Control Plan prior to commencing any mass concrete placement based on the design assumption that cracking of the concrete as a result of heat of hydration shall not occur. The duration of the cooling period depends on the Contractor's approach used in the Thermal Control Plan and needs to be predicted as part of the plan. Caltrans will accept the project when all provisions of the contract including the Thermal Control Plan have been satisfied.

14.0

Will trafffic control be required on the existing Bay Bridge, in either direction, during blasting operations?

Restrictions and safeguards in the blasting specification is such that noise, dust, or ground vibration due to blasting operation will not affect mainline traffic flow on the Bay Bridge. No traffic control is needed.

15.0

Are the US Coast Guard facilities available for contractors' use?

No. USCG docks, piers and facilities are not available for the contractors' use.

16.0

Ref plan page 24: Pipe supports PS-10 & PS-11 indicate that the Embed Plate "B" on M-2 should be used. There are no details for this Embed Plate. Where are these details?

On sheet M-5 (Sheet 24) when reference is made to plate "B" for PS-10 and PS-11, the contractor shall review tables provided on the same page.

In the "Table for PS-10" the "B" equals 4, thus indicating that contractor shall use embed plate #4 from drawing M-2 (Sheet 21).

17.0

This is in reference to Welded Hoops Testing Certification of Bar Size #36 shown on Detail F - F on Sheet 60 of 110. According to our Vendor/Supplier of welded hoops, Caltrans does not have an established certification for this specified bar size. Please verify if this is correct, and if not, can this be substituted to a smaller size that Caltrans has already approved and accepted?

Please bid according to the plans and specifications.

18.0

Ref Spec Section 10-1.35 sub section "MATERIALS" and plan pages 65 & 72:

The first paragraph of the MATERIALS section indicates that the HS rods are 75mm (2.95")diameter. The second paragraph states the duct diameter is 200mm (7.9"). This is much larger than we would expect. Is it correct? If so then the duct will interfere with the 50mm plate shown in Detail "H" on plan page 65. Also the prestressing notes do not give a P'jack or P'final. Note 3 just gives rod stress not exceed a maximum of 70% of the ultimate strength. What is P'jack for the rods?

The diameter of the duct may be adjusted to fit field conditions. The diameter shall be large enough to accommodate the HS rod and coupler. Macalloy may be contacted for standard duct size for the required HS rod and coupler.

Refer to Note 5 on plan sheet 63 of 110 for the jacking force in the high strength prestressing rods.

19.0

How detailed of an inspection are you expecting on the 120+ foot-tall Pier E1.  Is the request for a Photo Inspection truly a request for every square foot of the structure, up close and personal?

Existing SFOBB Pier E1 is founded on a slope. The existing pier is assessable from the Torpedo Factory Road and from the top of slope adjacent to the location of the new W2E pier. Unless there are unknown circumstances which require access to the top portion of the pier, it is reasonable to assume that photo survey may be performed on the ground with proper photo and video equipment.

20.0

Do you know if the painting scaffolds that currently hang under the bridge are useable?  If so, who manages them?

Painting Scaffolds are not made available to the contractors.

21.0

As a distributor of explosives we have been approached about supplying this project.

a.) Will any explosives storage be allowed on or near this project?

b.) Will the delivery of explosives be allowed over the bridge with escort?

c.) Is there a alternate plan for delivery of explosives if the bridge is not acceptable?

a) No.

b) No.

c) If the contractor elects to use explosives, they will be responsible to select the method for transporting the explosives. The method shall comply with all applicable specifications and regulations.

22.0

The plan views in the project plans seem to indicate that there are less than 50' between the new East pier footing to be constructed and the existing adjacent Bay Bridge footing. However, we are unable to find details or any elevations for the existing Bay Bridge footing structure in the contract plans or in any of the materials information provided with the bidder's package. Especially in view of the fact that blasting will be required to excavate a shaft about 91 deep feet for the new footing, we believe details of the existing bridge footing may be critical to our bid. Can Caltrans make as-builts of the existing footing structure available as part of the bidder's package?

Please refer to response to Inquiry #9 for information on existing Bay Bridge footing structure. Additionally, as-built plans of the existing San Francisco-Oakland Bay Bridge are available for inspection, upon written request, at the office of Duty Senior at the District 4 Office, 111 Grand Avenue, Oakland, California 94612, fax number: (510) 622-1805, email address: duty_senior_district04@dot.ca.gov, telephone number (510) 286-5209. When a request to review, inspect, or copy as-built plans is approved by the Duty Senior, the Contractor shall fill out and sign a "Confidentiality Agreement" form with the Department. When the Contractor's work is finished, the Contractor shall return all obtained as-built plans back to the Duty Senior at the District 4 Office.

23.0

Special Provisions 5-1.29 states that no in-water construction will be allowed within 200 m of the water-based ESA boundaries until the delineators have been placed, by others. How many days after NTP would this work by others be complete?

The ESA delineators will be placed prior to contract NTP.

24.0

Special Provisions 10-1.34 states that pile concrete is to contain 400 kg/m3 of cement while 10-1.36 says pile concrete is to contain 300 kg/m3 of cement. Please clarify.

Special provisions Section 10-1.34 states "Concrete deposited under slurry shall contain not less than 400 kg of cementitious material per cubic meter."

Special provisions Section 10-1.36 states "The cementitious content for piling shall be 300 kg/m3 minimum and the mineral admixture content shall be 35 percent of the cementitious material content."

Special provisions Section 10-1.36 applies to all piling (including where concrete is deposited under slurry). The concrete for piling deposited under slurry has the added requirement that it shall contain a minimun of 400 kg/m3 of cementitious material.

25.0

Special Provisions Section 5-1.13, as revised by Addendum 3, states "Construction of Pier W2 footings...shall not begin until" the ISD's are approved. Is "construction of footings" intended to mean the permanent concrete work only or does the restriction to begin work apply to the excavation of the footing and the work on the footing demonstration pour? Please clarify.

The footing demonstration pour and excavation of the footings may begin before the ISD's are approved.

26.0

It is our understanding that the "Areas for Contractors Use" for Contract No. 04-0120C4 shown on drawing C-6, with the exception of ESA areas, can be used for field offices, laydown yard, etc. and can be cleared of vegetation if necessary. Please confirm.

Within the restrictions outlined in the Contract Special Provisions, this is correct.

27.0

The allowable schedule duration for this project has been drastically changed from the prior bid. It was changed from 340 working days to 285 "working days" with a change in the definition of "working day". In changing the definition of a working day to count Saturdays, Sundays, legal holidays, and days of inclement weather as working days, this project has become a "calendar day" job.

The original duration of 340 working days resulted in a schedule of 13 to 16 months, depending on how many weather days you allow for. The new duration of 285 "calendar days" results in a schedule of only 9 months.

By shortening this project to 285 "calendar days", the timely completion of the work has become extremely sensitive to the submittal review, fabrication, and delivery of the sole-sourced Mac Alloy PT rods from England and the large tie-down anchorages.

The time required for the Mac Alloy PT rods submittal review, manufacture, and shipping takes about 180 days. If the review of the PT rod submittal started on the day of Notice to Proceed, this would leave 105 days to construct all the concrete structures since the bottom of the rods must be encased in the footing.

We arrived at 180 days by adding up the following durations. * 25 days for submittal review - Special Provisions 10-1.35, third paragraph under "Working Drawings" on page 172. Working days include Saturday, Sunday, and legal holidays. This assumes a perfect submittal as we did not allow additional time for re-submittal and re-review. * 120 days for rod fabrication - Mac Alloy Limited gave us a manufacturing duration of 17 weeks. * 35 days for delivery from the U.K. via ship and truck.

The remaining 105 calendar days, or 15 weeks, is insufficient to complete the project even working multiple shifts and 7 days per week.

We ask that you consider leaving the maximum allowable days at 285, but restore the Standard definition of "working day" for this project.

Section 3 of the Special Provisions has been revised. See Addendum #5. .

28.0

Reference Sheet 18, Utility plan U-1 shows 75 mm Water Main. There is no bid item for that size line. In the Specifications on Page 193 under Measurement & Payment it references "various sizes", however, it does not state under which item the 75 mm Water Main gets measured and paid. Under which bid item does this material get measured and paid? Please clarify.

There appears to be a discrepancy. Work not covered by a bid item will be paid as extra work at force account in accordance with Section 4-1.03D of the Standard Specifications.

29.0

In the original specification for this project, a working day was defined by the Caltrans Standard Specification Section 8-1.06 i.e. 5 working days per week. In the reissued specifications for the project, all days, including Saturdays, Sundays and legal holidays, become working days. By this redefinition, Caltrans has shortened the effective time to complete the contract by approximately 2/7ths, or 30%. If this is Caltrans intent, it will be virtually impossible to compete the contract in the time frame specified in the reissue documents. Please delete the reference that Saturdays, Sundays and legal Holidays, including days of inclement weather, will be counted as working days, and revert back to Standard Specification Section 8-1.06

Section 3 of the Special Provisions has been revised. See Addendum #5.

30.0

Please refer to Section 4 - PROPOSAL REQUIREMENTS AND CONDITIONS, of the Contract Documents. By Caltrans' redefinition of a "work day" as all days including Saturdays, Sundays, Legal Holidays, and days of inclement weather, the time available to the Contractor for completion of the project has effectively been reduced by a minimum of 30%. Unless the Contractor works around the clock for all available days, which will add substantial premium time and reduce labor productivity (increasing labor costs), it will be virtually impossible to complete the project in the time frame specified and within the Caltrans budget. Is this Caltrans' intent? Please advise in order for the project to be priced correctly.

Section 3 of the Special Provisions has been revised. See Addendum #5.

31.0

Recently, the California Department of Industrial Relations announced expanded coverage of the prevailing wage requirements to include off-site fabrication at permanent yards and shops of materials used in public works projects. Until now, fabrication off the site of a public work have not been subject to prevailing wage requirements unless they were performed in a temporary yard, plant, or other facility established primarily to perform work called for in the plans, specifications, or other documents. Will this new determination by the D.I.R. affect the material fabrications for the W2 project, especially the cable tie downs? Please advise.

The Department of Industrial Relation's (DIR) has stayed its two decisions on Prevailing Wage for Off-Site Fabrication.
See http://www.dir.ca.gov/DLSR/Notices/04-16-2003.pdf.
Work performed by contractors or subcontractors at off-site fabrication or prefabrication facilities will not be considered covered work until further notice by DIR.
If a site is set up solely to support the public work, even if it is "off-site", it is covered.
That determination has already been issued.
See http://www.dir.ca.gov/DLSR/Coverage/92-036.pdf.

32.0

Addendum 5 revises page 7 of the Engineers Estimate and lists Item 61 as Mobilization. Previously, Addendum 3 showed Item 61 as "Blank" and Mobilization was listed under Item 72. Please clarify.

Item #61 is "blank", and Item #72 is "Mobilization". The corrections have been made in Addendum #6, issued 4/14/03.

33.0

If marine life is present in the Marine Mammal Safety Zone;

a)Will the blast be held up?

b)How long will they wait for the Marine life to leave the MMSZ?

c)How will this delay be paid for if blasting is held up for hours/days?

a) The RE will inform the contractor when blasting can occur, which will be when the Marine Mammal Safety Zone is free of marine mammals.

b) Until the MMSZ is clear.

c) Any unreasonable delay will be considered a temporary suspension of work in conformance with Section 8-1.05, "Temporary Suspension of Work," of the Standard Specifications.

34.0

Caltrans plans sht. 38 of 110 states: "Structural Steel: A709 Grade HPS 485 unless noted otherwise on the plans." Caltrans plans sht. 65 of 110, Note 1, states: "All plate shall be ASTM A709M HPS 485W, unless specified otherwise." However, Caltrans Special Provisions, page 182, Sect. 10-1.39, Subsection, "Materials," states: "Structural Steel shall conform to ASTM designation: A709M, Grade HPS 485W or Grade 345 with supplementary requirement...," which means the two grades can be interchanged at the contractor's option, but conflicts with Caltrans plans sht. 38 & 65 stating only one grade (HPS 485W). The conflict is resolved by the Caltrans Standard Specs, Sect. 5-1.04, which states: "the Special Provisions govern over both these standard specs and the plans." Therefore, please confirm that the two subject grades of steel are optional contractor choices with respect to all structural steel plates in the Upper & Lower Tie-Down Base Frames, including the loose bearing platesfor the PT anchor rods. If Caltrans does not agree, please explain why not, and confirm what the structural steel specifications should be.

There is no conflict. The bidder's assumption of optional choices for all structural steel plates is incorrect. Sheet 38 is a general drawing, and sheet 65 is a detail drawing. Sect. 5-1.04 of the Standard Specifications states, "Detail drawings shall prevail over general drawings." Sheet 65, Note 1 states, "All plate shall be ASTM A709M HPS 485W, unless specified otherwise." Sheet 65, Note 5 states, "Steel pipe shall be ASTM A709M, Grade 345 unless specified otherwise." Section. 10-1.39, "Steel Structures," Subsection, "Materials," provides requirements for all structural steel materials for the contract, including, but not limited to, the steel plate and steel pipe shown on Sheet 65.