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CAMBRIA STANDARD FIELD PROCEDURES FOR GROUNDWATER MONITORING AND SAMPLING This document presents standard field methods for groundwater monitoring, purging and sampling, and well development These procedures are designed to comply with Federal, State and local regulatory guidelines Cambna's specific field procedures are summarized below Groundwater Elevation Monitoring Prior to performing monitoring activities, the historical monitoring and analytical data of each monitoring well shall be reviewed to determine if any of the wells are likely to contain non-aqueous phase liquid (NAPL) and to determine the order in which the wells will be monitored (i a cleanest to dirtiest) Groundwater monitoring should not be performed when the potential exists for surface water to enter the well (i a flooding during a rainstorm) Prior to monitoring, each well shall be opened and the well cap removed to allow water levels to stabilize and equilibrate The condition of the well box and well cap shall be observed and recommended repairs noted Any surface water that may have entered and flooded the well box should be evacuated prior to removing the well cap In wells with no history of NAPL, the static water level and total well depth shall be measured to the nearest 0 01 foot with an electronic water level meter Wells with the highest contaminant concentrations shall be measured last In wells with a history of NAPL,the NAPL level/thickness and static water level shall be measured to the nearest 0 01 foot using an electronic interface probe The water level meter and/or interface probe shall be thoroughly cleaned and decontaminated at the beginning of the monitoring event and between each well Monitoring equipment shall be washed using soapy water consisting of Liqui-nox"'M or . Alcono?Jm followed by one nnse of clean tap water and then two rinses of distilled water Groundwater Purging and Sampling Prior to groundwater purging and sampling, the historical analytical data of each monitoring well shall be reviewed to determine the order in which the wells should be purged and sampled (i e cleanest to dirtiest) No purging or groundwater sampling shall be performed on wells with a measurable thickness of NAPL or floating NAPL globules If a sheen is observed, the well should be purged and a groundwater sample collected only if no NAPL is present Wells shall be purged either by hand using a disposal or PVC bailer or by using an aboveground pump (e g peristaltic or WatteraTM) or down-hole pump (e g Grundfosrm or DC Purger pump) Groundwater wells shall be purged approximately three to ten well-casing volumes (depending on the regulatory agency requirements) or until groundwater parameters of temperature, pH, and conductivity have stabilized to within 10% for three consecutive readings Temperature, pH, and conductivity shall be measured and recorded at least once per well casing volume removed The total volume of groundwater removed shall be recorded along with any other notable physical characteristic such as color and odor If required, field parameters such as turbidity, dissolved oxygen (DO), and oxidation-reduction potential (ORP) shall also be measured prior to collection of each groundwater sample Groundwater samples shall be collected after the well has been purged If the well is slow to recharge, a sample shall be collected after the water column is allowed to recharge to 80% of the pre-purging static water level If the well does not recover to 80% in 2 hours, a sample shall be collected once there is enough groundwater in the well Groundwater samples shall be collected using clean disposable bailers or pumps (if an operating remediation system exists on site and the project manager approves of its use for sampling) and shall be decanted into clean containers supplied by the analytical laboratory New latex gloves and disposable tubing or bailers shall be used for sampling each well If a PVC bailer or down-hole pump is used for groundwater Paee 1 of 2