2014-01-29_HYDROLOGY - P2009025 (8)

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SOP for Surface Water Sampling — Hansen Project 2 3. SAMPLING PROCEDURES This section provides step -by -step procedures for collecting surface water quality samples in the field. Observations made during sample collection will be recorded in the fieldbook and field data sheet as specified below. If multiple stations exist on the same stream, sampling will begin at the most downstream monitoring site and continue upstream to avoid disturbance from upstream areas prior to sampling. 3.1 Selection of Sampling Methods This section discusses the criteria for the selection of sampling methods and equipment. The selection of sampling methods and equipment is based on sample type, flow conditions, and data quality objectives stated in the field sampling plan. Selection of sampling methods and equipment based on flow condition is described in Table 1. Table 1. Collection Methods and Devices Based on Stream Dimensions Stream Stream Method Device(s) Width Depth Grab from center of stream Polyethylene or glass sample <3 ft <1 ft container Grab from thalweg, if defined Polyethylene sample container, 3 - 5 ft Approx. 1 ft Else, grab from center of stream swing sampler with short pole or horizontally integrated composite Vertical composite integrated from Polyethylene sample container, >5 ft >1 ft thalweg swing sam ler with long pole Too deep to Vertically integrated composite or Kemmerer -type sampler Any width grab discrete samples at designated depths • If depth is less than one foot and the stream is less than three feet wide, collect samples from the center of flow. Use a decontaminated polyethylene or glass sample container and clean latex gloves. Dip the sample and transfer into the sample bottles. • If depth is about one foot in depth and the stream is three to five feet wide, use the swing sampler (Figure 1) to collect the sample from the thalweg (deepest portion of the stream). If the thalweg is not defined, collect the sample from the approximate center of the stream. Alternatively, use the horizontal areal composite method: Collect aliquots of sample from three stations spaced evenly across the stream. Combine these in a clean (decontaminated) container. • If depth averages greater than one foot and the stream is at least five feet wide, use the swing sampler to collect a vertically integrated sample from the thalweg . If the thalweg is not defined, collect a vertically integrated sample from the approximate center of the stream. • If the stream or water body is too deep to collect grab samples using the swing sampler and the longest extension rod, use the Kemmerer — type sampler to collect samples at depth. If a composite sample is desired, collect samples at uniform depths, composite the samples in a clean container, and fill the sample bottles from the composite. Samples will be collected from the same cross section of the stream that is to be used for the flow measurement, if stream flow is measured. Where samples are to be collected downstream of a confluence: the sample location will be selected at least 100 feet downstream of the confluence or as appropriate to allow proper mixing of stream waters. Always collect samples prior to making flow measurements. Remain on the bank, or stand downstream of the water to be sampled. 4153A.140129 Whetstone Associates