Protecting Oregon's Environment
Oregon State Seal
Oregon Department of Environmental Quality

Land Quality

Environmental Cleanup

green envelope icon Sign up for email updates on the Environmental Cleanup Program
Dry Cleaners
Emergency Response
Orphan Sites
Prospective Purchasers Agreement
Site Assessment
Site Response
Voluntary and Independent Cleanup
Conferences, Training & Workshops

Expanded Preliminary Assessment Sampling Plan Guidance


The Quality-Assurance Plan should discuss all of the following:

  1. data-quality objectives for precision, accuracy, and completeness, including description and frequency of QA/QC samples to be collected/analyzed, to assess data quality;
  2. data-quality assessment procedures; and
  3. data-quality reporting.

The following standards must be maintained during sampling and analysis to ensure that the data generated for the XPA meets DEQ data-quality objectives:


  • Collect background, duplicate, blank, etc. samples in percentages or numbers specified below in QA/QC SAMPLING GUIDELINES.
  • Use pre-cleaned equipment to perform all sampling , and follow sampling procedures specified in DEQ or EPA guidance.
  • Collect samples in pre-cleaned bottles; label, store, and transport the samples according to DEQ or EPA guidelines.
  • Maintain strict chain-of-custody from sample collection until the samples are received by the analytical laboratory.
  • Use field notes and photographs to document all sampling activities and any deviations from the original sampling plan.


  • All sample analyses must be performed within the holding time specified for each individual analysis; note any exceptions in the final report.
  • Laboratories must follow the individual protocols specified by EPA or DEQ for the analytical methods used.
  • Internal laboratory procedures such as lab blank and surrogate analysis will be performed as follows, unless otherwise requested by DEQ:
  1. all VOC or BNA samples will receive surrogate spike analysis; and
  2. matrix spike analysis will be performed on at least every 20th sample; if less
  3. than 20 samples are collected, at least one matrix spike analysis will be performed.
  • Labs must report results of all internal laboratory QA/QC procedures such as lab blank, matrix spike, and surrogate analyses.
  • In addition to analytical results, analytical data sheets generated by the laboratory for the XPA will each contain the following information: sample number and laboratory identification number, analysis method type or number, detection limits, and date of analysis.
  • The lab must document any problems it encounters regarding chain-of-custody, sample holding times, sample analyses, lab contamination, etc., and these must be discussed in the XPA report.

QA/QC Sampling Guidelines

Background Samples
Sampling to determine the background levels of naturally occurring and man-made chemicals should be carried out as part of any routine sampling program. Background areas should be removed from facilities that may have contributed contamination to the environment, and should be upgradient, upwind, and upstream of such facilities. These areas should also be near enough to the site to have similar topographical features and the same or very similar soil types. The parent material for the soil should be the same, if at all possible. Collect at least one background sample, when appropriate, for each sample matrix and parameter selected. Background samples should be preserved, packaged, and sealed the same way as any other sample. Assign a separate sample number to each background sample, and submit it "blind" to the laboratory.

Duplicate Samples
Duplicates are two identical samples collected at the same time from the same source, but placed in separate sample containers. The purpose of collecting a duplicate is to assess laboratory performance by comparing what should be identical results. Duplicate samples should be collected from areas of known or suspected contamination, and should make up at least 10 percent of samples from each sample matrix and every analytical group to be tested.

Blank Samples
Blanks are used to determine whether sampling equipment, sampling technique, or sample transport has induced contamination that is not actually present in the environment. When required, one blank sample should be collected per day. There are several types of blanks, as explained below.

  1. Equipment Blanks
    An equipment blank should be collected when sampling equipment is decontaminated and reused in the field, or when a sample collection vessel (bailer, beaker) will be used. Equipment blanks are designed to evaluate field sampling and decontamination procedures. These blanks are prepared by passing organic-free (for organics) or deionized water (for inorganics) through decontaminated sampling equipment before filling the sample bottles. One equipment blank should be prepared per day when equipment blanks are needed. Note that the use of dedicated sampling equipment eliminates the need for blanks.
  2. Field Blanks
    Collect this type of blank when equipment decontamination is not necessary and when a sample collection vessel will not be used (bailer, pump, etc.). The purpose of field blanks is to evaluate the general sampling environment. The field bottle blank should be poured at a sampling point. Use the appropriate "blank" water: organic-free water for organic parameters, and deionized water for inorganic parameters.
  3. Trip/Travel Blanks
    Trip or travel blanks evaluate potential sample contamination from volatile organic compounds (VOCs) that may be present in the air on-site or in sample shipping containers. A trip blank consists of laboratory distilled, deionized water in a closed container. The blank accompanies the empty sample bottles to the field as well as the samples returning to the lab for analysis; it is not opened until the lab analyzes it with the actual site samples. When needed, one trip blank should be prepared by the sample laboratory and analyzed upon return for each sampling event.

Laboratory QC Samples
Laboratory quality control (QC) samples should be collected and analyzed as part of standard laboratory protocols. A laboratory QC sample is not an extra sample, but consists of additional sample volume from specific sample locations where there is known or suspected contamination. For a given sample, this extra volume provides the laboratory with sufficient material to duplicate its analyses or conduct matrix spike analyses. Bottle labels, traffic reports, and chain-of-custody records for these samples must identify them as laboratory QC samples. Designate one field sample per week or one per 20 samples (including blanks and duplicates), whichever is greater, as the QC sample. It is good practice to check with the analytical laboratory regarding the additional sample volume required for laboratory QC samples prior to sampling.

Health and Safety Plan

Prepare a Health and Safety Plan with the XPA sample plan for all sites where DEQ personnel or persons performing contract work for DEQ will be involved in on-site activities. At a minimum, the Health and Safety Plan should:

  • Describe known site hazards and risks;
  • Identify appropriate levels of protective clothing and equipment for site work;
  • Describe decontamination procedures and means of handling, storing, and disposing of investigation-derived wastes;
  • Identify any special requirements or training needs, and verify that all staff participating in site work are adequately trained; and
  • Outline a contingency plan for emergencies.
[print version]


For more information about DEQ's Land Quality programs, visit the DEQ contact page.

Oregon Department of Environmental Quality
Headquarters: 700 NE Multnomah Street, Suite 600, Portland, OR 97232
Phone: 503-229-5696 or toll free in Oregon 1-800-452-4011
Oregon Telecommunications Relay Service: 1-800-735-2900  FAX: 503-229-6124

The Oregon Department of Environmental Quality is a regulatory agency authorized to protect Oregon's environment by
the State of Oregon and the Environmental Protection Agency.

DEQ Web site privacy notice