Enc(1)_Government Response_A0002_22Jun2020.pdf

SOLICITATION NO. N4008420T5410

PROJECT TITLE/LOCATION: LANDFILL LONG TERM MONITORING SAMPLING AT U.S. MCAS IWAKUNI, JAPAN

Amendment 0002 Enclosure (1)

Page Section Para.

Amend No.

Question No.

Date Received

REFERENCE

QUESTION GOVERNMENT RESPONSE

17‐Jun‐201 Specific requirements in the PWS requiring a low‐flow technique for groundwater sampling will not be changed. We will require contractor to adhere to the language in the PWS to use a "low‐flow technique" utilizing a peristaltic pump. Previous response referenced should have been clearer that usage of bailers would not meet intent of the PWS language.

After reviewing the government's response to Question 3, we are wondering if the government is going to change the requirements in the PWS. The PWS states that "the monitoring wells will be sampled using a low‐flow technique for one hour or until the groundwater parameters stabilize." Is the government changing the requirement from a low‐flow technique to allow the use of bailers? We have some concerns about changing sampling methodologies for groundwater monitoring at the landfill and the effect it could have on data comparability between the current project and the new one.

The EPA has stated in its low‐flow groundwater sampling procedures not to use a bailer to collect low‐flow groundwater samples because "bailers and other grab type samplers are ill suited for low‐ flow sampling since they will cause repeated disturbance and mixing of stagnant water in the casing and the dynamic water in the screened interval [and] use of these devices also tends to introduce uncontrolled and unacceptable operator variability."

The PWS also states that the contractor shall provide "a water‐level probe, peristaltic pump, multi‐parameter probe with flow cell, and a turbidity meter" for collecting the samples. It has been shown during the current and previous monitoring projects at the site that a low‐flow peristaltic pump generates sufficient lift to collect samples and therefore a bailer is not necessary to collect samples.

Please clarify whether the government is going to require sampling using a low‐flow technique with a peristaltic pump as required in the PWS or whether the government is going to allow alternative sampling methods such as using bailers to collect the groundwater samples.