2005/05/04 Council Agenda Packet

5 • Temporary work platform (Item 21) Further descriptions of the these differences are summarized below: Mobilization (Item 1) The engineer's opinion of probable cost assumed mobilization project costs to equal approximately five (5) percent of the subtotal construction cost. Mobilization costs typically include items such as procuring the project field office, preparation of shop drawing submittals, mobilization of equipment, B&O taxes, and other administrative costs that occur during the startup of the project. The mobilization costs found in the three-bid schedules ranged from a low of 7.1% to a high of 12.3% of the subtotal cost for other bid items. The higher percentages used by the bidders in the mobilization bid item becomes even more significant due to the larger subtotal of the bid prices reflected in the bid proposals resulting from some of the other bid items. For example, the higher mobilization percentage used in the low bidder's (Tri-State) proposal for Bid Schedule C (7.1%) as compared to that used in the engineer's opinion of probable cost (5%) results in an additional cost of$772,468. Elevated Walkway— Pipelines No. 2 & 3/Pipeline No. 4 (Items 26, 27 and 64) The engineer's opinion of probable cost for the elevated walkways was based on a unit cost price of $70 for the walkway between Pipelines 2 and 3 (bid Item 26) and $40/lineal foot for the Pipeline 4 walkway (bid items 27 and 64) compared to the low bidder's unit cost of$135/lineal foot for each item. This represents a total cost difference of $1,057,600. Several factors may account for this cost difference including under estimating the crew time required, the restricted access requirements and the volatility in the steel price industry (steel beams and walkway grating). It also appears that the low bidder did not differentiate between the cost of the Pipeline 2/3 walkway (involving a 5 ft wide grating and two W12 x 58 longitudinal steel beams), and the Pipeline 4 walkway(involving only a 3-ft 4-inch walkway and no longitudinal beams) Install/ Remove Temporary Work Platform (Item 21) As described previously, the engineer's opinion of probable cost was based on an assumed construction access method involving a temporary work platform supported directly on the permanent steel piles. This approach minimizes the number of temporary pile bents required for construction access. The permanent pile bents are capable of supporting a 150-ton crane load plus the working platform weight. Responsibility for the design of the temporary work platform remains with the Contractor, based on their construction plan. The three bidders that proposed on the Phase 6 work developed three different concepts for the temporary work platform, resulting in costs ranging from $4.22 to $7.10 million. This price is substantially higher than the $1.65 million shown in the engineer's opinion of probable cost. This bid item alone accounts for a difference of$5,049,136 between the engineer's opinion of probable cost and the low bidder's price. There are several factors directly impacting the cost of the temporary work platform that appear to have contributed to this significant cost difference, as described below: 1. Restrictions on timing of in-water activities: During the original design work no winter timing restrictions were anticipated for the construction work. However, near the end of the design phase, the Corps of Engineer's Nationwide-permit imposed MWH—TECHNICAL MEMORANDUM Page 3 TRANSMISSION LINES 2&3—PHASE 6&7 APRIL 22,2005 ASSESSMENT OF BIDDER'S PRICE PROPOSALS 15