Large Volume Samples for Organic Compound Determinations
Assorted Sensitive Inorganic Species NOf, NH4+, Fe(II)
Trace Metals for Mobile Substance Load+++
Trace Metal Samples for Specific Geochemical Imformation+++
S a, Sensitive Inorganics i
Major Cations and Anions
Representative Water Access
Verification of Representative Water Sample Access
Sample Collection by Appropriate Mechanism
Minimal Sample Handling
Head-Space Free Samples
Minimal Aeration or Depressurization
Minimal Air Contact, Field Determination
Adequate Rinsing against Contamination
Minimal Air Contact, Preservation
Pump water until well purging parameters (e.g., pH, TC'1, Eh) stabilize to ± 10% over at least two successive well volumes pumped.
Pumping rates should be limited to ~ 100 mL/min for volatile organics and gas-sensitive parameters.
Filter: Trace metals, inorganic anions/cations, alkalinity. Do not filter: TOC, TOX, volatile organic compound samples. Filter other organic compound samples only when required.
Samples for determinations of gases, alkalinity, and pH should be analyzed in the field if at all possible.
At least one blank and one standard for each sensitive parameter should be made up in the field on each day of sampling. Spiked samples are also recommended for good QA/ QC.
Minimal Loss of Sample Integrity Prior to Analysis
Observe maximum sample holding or storage periods recommended by the agency. Documentation of actual holding periods should be carefully performed.
* Denotes samples that should be filtered to determine dissolved constituents. Filtration should be accomplished preferably with inline filters and pump pressure or by N2 pressure methods. Samples for dissolved gases or volatile organics should not be filtered. In instances where well development procedures do not allow for turbidity-free samples and may bias analytical results, split samples should be spiked with standards before filtration. Both spiked samples and regular samples should be analyzed to determine recoveries from both types of handling.
** Denotes analytical determinations that should be made in the field.
FIG. 9.15.4 Generalized flow diagram of groundwater sampling protocol. (Reprinted from U.S. Environmental Protection Agency, 1993, Subsurface characterization and monitoring techniques, a desk reference guide, Vol. 1, USEPA/625/R-93/003a [May] U.S. EPA.)
Was this article helpful?