40 CFR § 761.247 - Sample site selection for pipe segment removal.

§ 761.247 Sample site selection for pipe segment removal.

(a) General.

(1) Select the pipe segments to be sampled by following the directions in paragraph (b) of this section.

(2) Locate the proper position along the length of the pipe segment that you have selected for sampling, by following the directions in paragraph (c) of this section.

(3) Select the proper sampling position around the circumference of the pipe segment that you have selected for sampling, by following the directions in paragraph (d) of this section.

(4) Prior to removing pipe from the ground or lifting the pipe from its location during former operations, mark the top side of the pipe.

(5) Do not sample if there are free-flowing liquids in the pipe segment. Free-flowing liquids must be removed prior to sampling.

(b) Selecting pipe segments to sample. Select the pipe segment(s) that you will sample from a length of pipe or group of pipe segments, as follows:

(1) Do not sample a pipe segment that is longer than 12.2 meters (40 feet). If a segment is longer than 12.2 meters in length, cut the segment so that all resulting segments are 12.2 meters or less in length.

(2) Determine which pipe segments to sample as follows:

(i) When a length of pipe having seven or fewer segments is removed for purposes of disposal, sample each pipe segment.

(ii) When removing a length of pipe having multiple contiguous segments less than 3 miles in total length, take samples from a total of seven segments.

(A) Sample the first and last segments removed.

(B) Select the five additional segments according to one of the two following procedures:

(1) Assign all segments a unique sequential number. Then select five numbers using a random number table or random number generator. If the random number generator or random number table produces either the first pipe segment, the last pipe segment, or any previously selected segment, select another random number until there are seven different numbers, each corresponding to a different pipe segment.

(2) Divide the total number of segments by six. Round the resulting quotient off to the nearest whole number. The resulting number is the interval between the segments you will sample. For example, cut a 2.9 mile length of pipeline into 383 segments of approximately 40 feet each. Sample the first (number 1) and last (number 383) segments. To determine which additional five segments to sample, divide the total number of segments, 383, by 6. Round up the resulting number in this example, 63.8, to the next whole number, 64. Add 64 to the number of each preceding pipe segment five separate times to select five additional pipe segments for sampling. In this example, the first pipe segment has the number 1, add 64 to 1 to select segment 65. Next, add 64 to 65 to select segment 129. Continue in this fashion to select all seven segments: 1, 65, 129, 193, 257, 321, and 383.

(iii) When removing a length of pipe having multiple contiguous segments more than 3 miles in total length for purposes of disposal, take samples of each segment that is 1/2 mile distant from the segment previously sampled. Sample a minimum of seven segments.

(c) Selecting the sampling position - length. Select the sampling position along the length of the pipe segment, as follows:

(1) Take samples at the end upstream of the former gas flow of each segment removed.

(2) If the pipe segment is cut with a torch or other high temperature heat source, take the sample at least 15 cm (6 inches) inside the cut end of the pipe segment.

(3) If the pipe segment is cut with a saw or other mechanical device, take the sample at least 2 cm (1 inch) inside the end of the pipe segment.

(4) If the sample site location selected in the procedure at paragraph (c)(2) or (c)(3) of this section is a porous surface (for example, there is significant corrosion so that the wipe material will be shredded), then move the sample site further inside the pipe segment (away from the end of the pipe or pipe segment) until there is no such porous surface. For purposes of this subpart, natural gas pipe with a thin porous corrosion preventive coating is a non-porous surface.

(5) If there is not a non-porous surface accessible by paragraphs (c)(2) and (c)(3) of this section, use one of the following three options:

(i) Sample the downstream end of the pipe segment using the same sample site location procedure as for the upstream end.

(ii) Select another pipe segment using the random selection procedure described in paragraph (b) of this section.

(iii) If there is no other pipe segment in the population to be sampled and both ends of a pipe segment have porous surfaces at all possible sample collection sites, then assume that the pipe segment contains ≥50 ppm PCB but <500 ppm PCB.

(d) Selecting the sample position - circumference. Based on the mark on the top of the pipe segment made prior to removing pipe from the ground or lifting the pipe from its location during former operations, sample the inside center of the bottom of the pipe being sampled. Make sure the sample is centered on the bottom of the pipe segment; that is, sample an equal area on both sides of the middle of the bottom of the pipe segment for the entire length of the sample.

[63 FR 35462, June 29, 1998, as amended at 64 FR 33762, June 24, 1999]

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