8-1 Water

Please provide a process and instrumentation diagram for the proposed GAC treatment system.

8-1       GAC Treatment following Extraction at the Pascoag Well – The proposed granular activated carbon (GAC) treatment system needs to be evaluated.  In Table 6.2-2 of the October 2015 application, the proposed MTBE concentration going to the proposed plant is 55 µg/L, and following use at the plant as cooling water, the compositional projection of MTBE going to the Burrillville WWTP is 200 µg/L.  Please provide a process and instrumentation diagram for the proposed GAC treatment system.

RESPONSE: 8-1

 

The design of the granular activated carbon (“GAC”) will be such that water supply to the plant will be below drinking water standards and we will control to reduce MTBE to 40 ppb after the first vessel and the second vessel will remove the remaining MTBE to a non-detect level, but we conservatively assumed that a max limit of 40ppb could get past the second vessel and this was the basis for the 200 ppb in the waste stream. The normal operating flow to the waste water treatment plant will not contain any MTBE.

 

Engineering for the water treatment system is in the early stages of design; therefore, no piping and instrument diagrams are available at this time.  Attached as Exhibit 1 is a pictorial flow diagram that shows the basic process steps for the system. 

 

RESPONDENT:

 

Amit Nadkarni, Invenergy Thermal Development LLC

 

DATE:

May 16, 2016