QUESTIONS_2_SNELL_HFM_SLOT_INSTALLATION.pdf

HFM SLOT INSTALLATION @ SNELL LOCK

RFP NO. DTSL5517R0681

QUESTIONS AND ANSWERS

AUGUST 14, 2017

1. Q: We can find no rebar shown on the record drawings other than at two locations, the oil tank support/recess and the parapet curb. If there are other locations where rebar is known to exist, please provide the location, rebar size & spacing.

A: All reinforcing steel (rebar) that was designed into the project and is known to exist is shown on the reference drawings. Nominally, except for isolated small concentrations of rebar as shown, the lock wall monoliths are unreinforced mass concrete.

2. Q: The presence of concealed obstructions, including reinforcing steel, will extend the duration and increase the cost of demolition operations. At how many locations should the contractor anticipate encountering concealed obstructions such as reinforcing steel, timber, etc.? Please provide guidance as there is no information upon which to base a bid.

A: The quantities of unanticipated steel reinforcing bar or other embedded extraneous matter, being unplanned random occurrences, cannot be predicted with any accuracy. The experience with a similar project at Eisenhower Lock indicated that the wall slot demolition encountered scattered small amounts of embedded steel, much of which did not show on any drawings. The west slot encountered 84 pieces of steel, the center slot had ~35 pieces of steel and the east slot had 33 pieces of steel. This was over the entire

~75-foot height of each slot. The steel consisted mostly random of short lengths of no. 6 to no. 11 that ranged up to about 6 feet in length, a few 2” angles, and 2”-3” pipes that did not show on any drawings. This steel was not designed in, but believed to have been thrown in randomly. The wall armor had angles associated with its anchorage that did not show on any drawings. These angles can be expected at all wall armor embedments.

3. Q. Also, when the guardrail was installed at the Snell Lock was reinforcing steel or other obstructions encountered when core drilling? Please advise.

A: At four railing post hole core locations at Snell, out of about 200 total, steel was encountered that caused some difficulty in removing the cores. In those cases, the steel was oriented vertically or near-vertically and extended below the 24-inch termination depth of the core hole, thus the concrete had to be broken up and then the steel cut with a torch. None of these locations was within the slots area. The railing was not constructed in the same monoliths that are to receive the slots.