Site Visit Q&A.doc

Option Clarification Question #1 - At the site visit, there were numerous questions regarding the frequency of test holes, and whether we were willing to reduce the Subsurface Utility Engineering (SUE) quality to Type “B”.

Answer #1 - To obtain the highest accuracy with the funds available we adjusted the price schedule to include price options based on the number of test holes that will be required. See the options below for more detail. In addition, the SUE designated in the original specification will remain as Type “A”.

The following option descriptions clarify the frequency of non-destructive digging referenced in the technical specifications. These options are in addition to the project specifications.

Option #1 Gas lines shall be exposed by means of non-destructive vacuum exposure (hydro or air) every 1250 feet at a minimum unless there is a change in direction or a intersection in the line. At this point, the line shall be exposed and surveyed at the midpoint of this change in direction/intersection to minimize the frequency of non-destructive digging. If a valve is located in the path of the line, the valve shall be used to mark XY instead of exposing the pipe and marking XYZ. This may eliminate a test hole in some cases, and the minimum distance from test hole to test hole would then reset. For areas directly around buildings, if there is adequate signal from the tracer wire, the contractor will not be required to expose the pipe within 20 feet of the building as the service line will have an XYZ from exposure and there will also be an XY from where the gas piping emerges to enter the outside of the building. Using the tracer signal, XYZ, and XY, this should be sufficient information to map the line. For all other areas, if tracer wire is not available, the line shall be exposed every 500 feet. Assume that 7.5% of the overall gas system has no tracer wire.

Option #2 Gas lines shall be exposed by means of non-destructive vacuum exposure (hydro or air) every 1000 feet at a minimum unless there is a change in direction or a intersection in the line. At this point, the line shall be exposed and surveyed at the midpoint of this change in direction/intersection to minimize the frequency of non-destructive digging. If a valve is located in the path of the line, the valve shall be used to mark XY instead of exposing the pipe and marking XYZ. This may eliminate a test hole in some cases, and the minimum distance from test hole to test hole would then reset. For areas directly around buildings, if there is adequate signal from the tracer wire, the contractor will not be required to expose the pipe within 20 feet of the building as the service line will have an XYZ from exposure and there will also be an XY from where the gas piping emerges to enter the outside of the building. Using the tracer signal, XYZ, and XY, this should be sufficient information to map the line. For all other areas, if tracer wire is not available, the line shall be exposed every 500 feet. Assume that 7.5% of the overall gas system has no tracer wire.

Option #3 Gas lines shall be exposed by means of non-destructive vacuum exposure (hydro or air) every 750 feet at a minimum unless there is a change in direction or an intersection in the line. At this point, the line shall be exposed and surveyed at the midpoint of this change in direction/intersection to minimize the frequency of non-destructive digging. If a valve is located in the path of the line, the valve shall be used to mark XY instead of exposing the pipe and marking XYZ. This may eliminate a test hole in some cases, and the minimum distance from test hole to test hole would then reset. For areas directly around buildings, if there is adequate signal from the tracer wire, the contractor will not be required to expose the pipe within 20 feet of the building as the service line will have an XYZ from exposure and there will also be an XY from where the gas piping emerges to enter the outside of the building. Using the tracer signal, XYZ, and XY, this should be sufficient information to map the line. For all other areas, if tracer wire is not available, the line shall be exposed every 300 feet. Assume that 7.5% of the overall gas system has no tracer wire.

Question #2 - What is the accuracy of the gas system map provided in the RFP? Meaning the accuracy of the marks that were surveyed, not the survey itself?

Answer #2 – The accurancy of the current GIS is mapping grade.

Question #3 – Who marked the lines that were surveyed?

Answer #3 – The lines were surveyed by government Engineering technicians.

Question #4 – Will the contractor be liable for the final mapping that is submitted? In addition, how will it be determined if a contractor digs on an area where vacuum excavation was not performed and they hit or damage a gas line?

Answer #4 – The contractor will be 100% liable for areas where the vacuum excavation was performed. This should be documented in the final report, and the Government will be liable up to the accurancy of the electronic magnetic readings and/or Ground Penetrating Radar (GPR) for areas between each vacuum excavation or gas valve.

Question #5 – What is your estimate of plastic pipe for the entire system and how much would you estimate does not have trace wire?

Answer #5 – There is approximately 113,000 linear feet of polyethylene gas pipe that will be surveyed under this contract. Of that 113,000, assume that 7.5% does not have tracer wire.

Question #6 – Does a test hole form need to be submitted for each location where the pipe is exposed?

Answer #6 – Test holes shall be documented in the final report.

Question #7 – Can the survey point be taken from a PK nail or a wooden hub installed in the ground directly over the centerline of the pipe as opposed to the surveyor having to shoot the pipe directly?

Answer #7 – We will allow the test holes to be open up to seven days. This should minimize the time spent by the surveyor onsite. All excavations shall be protected by orange construction fence as a minimum. If an elevation is taken at the time of the excavation, we will allow the use of a PK nail to designate XY location until the surveyor can mark the point.