Collecting a Representative Sample - Sampling Methodologies (con’t) D. Surficial Contamination - Chip or Wipe Samples Examples: Lead paint on concrete Battery acid spill on concrete PCB-contaminated oil
Collecting a Representative Sample – Sampling Strategy Sampling Strategy - making sure the sample reflects the characteristics of the population or media being sampled a.Biased Sampling (looking for “worst case”) b.Composite Sampling (looking for “average”) c.Grab Samples (specific location / time) d.Random Sampling (unknown or variable concentrations) i.Simple ii.Stratified (sampling based on varying colors/grain size) iii.Systematic (grid pattern)
Sampling Safety Up to date H&S Training Recommend a H&S Plan (incl. physical hazards) Familiar with chemical, MSDS, routes of exposure Proper PPE –Consider Exposures and probability for spillage –Level D: long sleeves, protective glasses, proper sampling gloves (e.g. nitrile is most universal) –Level C: Tyvek, boots, face shield, respirator
Sampling QA/QC B.Custody Procedures 1.Samplers Objective Site / Project Information Sample ID / Number of sample containers Preservation Requested Analyses Special Notations (i.e., HOLD, report to MDL) Custody Signatures
Sampling QA/QC What is “Custody”? The National Enforcement Investigations Center (NEIC) of the U.S. EPA defines custody as: 1. The sample is in your physical possession; 2. The sample is within view after being in your physical possession; 3. The sample was in your possession and then you locked or sealed it to prevent tampering; and/or 4. The sample is placed in a designated secure place with limited access to authorized personnel only.
Sampling QA/QC B.Custody Procedures 1.Lab Objective COC is the master document of communication between sampler and lab COC used to catalog sample and assign a unique lab ID number Lab will notify of problems or discrepancies (identification discrepancies, shipping problems, preservative problems)