Dutra Dredging Company
Our letter No. 161 identified the situation at the U.P.R.R. dike location and the facts the Navy has information that there 2 sewer lines crossing the Inner Harbor in the location of the new crossing. That letter also suggested a possible solution to the slope stability issue by moving the location of the pipe landfall 500 feet to the east.
We had hoped that all of the parties involved could get together and devise a solution to the many facets of the differing site conditions. However, after the weekly meeting on Tuesday, September 3, it appears we need to take a more formal approach. This letter is to formally advise you of the changes of conditions that exist.
The waterside slope at the Union Pacific Railroad location of the landfill of the sewer line has dramatically steepened from conditions shown on the contract drawings. This apparently as a result of the 1989 earthquake. The U.P.R.R. has brought in rock by railcar and side dumped to create a rock berm between the tracks and the edge of the water. Your staff has been provided cross-sections showing the existing conditions super-imposed over the cross-section on the plans.
The railroad has required that construction methods maintain slope stability and guarantee stability. The railroad also insists on using the track at all times.
Neither of these requirements was known prior to the bid.
Serial Letter No. 0167
With the rock in place from railcar side dumping we are unable to drive H beams and plates as ordered on the plans. We cannot excavate the rock and still assure stability. It is not possible to guarantee stability at that location while jacking a casing under the tracks as prescribed on the drawings.
We have offered a possible solution by way of an alternate landfall site 500 feet east of the plan location. This site would allow slope excavation without endangering slope stability. However, use of this site would result in the need for 700+/- feet of additional pipeline. We maintain that this alternate site may actually be less costly at the end than trying to devise an exotic method of assuring the U.P.R.R. of slope stability at the plan location.
The other item that must be determined is if there actually is a second pipeline crossing the Inner Harbor at the plan location. An, if there are two, which is the line line.
As we stated in our serial letter No. 0161, time is of the essence. The lead time on more pipe is 100 days per the manufacturer. It is critical that we be advised how to continue.
We are willing to do whatever we can to assist in solutions to the above illustrated dilemma.
Thank you for your assistance.
Robert D. Johnston President