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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.Cambria's specific field procedures are summarized below. Grou"ndwaterElevation 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.e. cleanest to di iest). Groundwater monitoring should not be performed when the potential exists for surface water to enter the well(i.e.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. Monitoriequipment washed using oapy ter Alconoxgfoto ed by one arinse ll e of clean tap water rand henatwo rinses sof distilled ting of sor 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 les.If a sheshall be is observed the well should wells with a measurable thickness of NAPL or floating NAPL globu 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 orry using an aboveground pump (e.g. peristaltic or WatteraTm)or down-hole pump(e.g.Grundfos 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 Page 1 of 2