From: Rob Ede
Sent: Mon Sep 29 12:20:55 2014
To: BAYUK Dana
Cc: Bob Wyatt; Patty Dost; Ben Hung; Taku Fuji; John Edwards; John Renda; Carl Stivers; Sarah Riddle
Subject: Updated "3Q14" GW Monitoring Program - w TPH added
Importance: High
Attachments: 3Q14 Integrated with TPH Proposal_140929.pdf; Dana, As you requested during our September 24, 2014 telephone conversation I am providing on behalf of NW Natural a revision to the table previously provided to DEQ in e-mail correspondence dated September 5, 2014. The referenced table describes the locations and analyses to be conducted as part of the next groundwater monitoring event completed by NW Natural at the Gasco and Siltronic properties. As you are aware, this event was previously approved for implementation but was delayed due to discussions necessary subsequent to DEQ's request/requirement for collection of total petroleum hydrocarbon (TPH) data during this event, including gasoline-range (NW-TPH Gx); diesel- and oil-ranges (NW-TPH-Dx); and TPH fractions (WDOE VPH and EPH Methods). Based on our discussion yesterday, NW Natural has revised the previously provided table to include the following locations/analyses described by DEQ as being necessary for adequate spatial coverage. I. Incorporated NW-TPH-Dx; NW-TPH-Gx; WDOE EPH and WDOE VPH analyses to the following Gasco shoreline wells already scheduled for sampling during the next event:
II. Incorporated the following Gasco upland wells for sampling and NW-TPH-Dx and NW-TPH-Gx analyses (only) - no other analytes on the standard parameter list are proposed.
III. Incorporated NW-TPH-Dx, NW-TPH-Gx; WDOE-EPH and WDOE-VPH analyses to the following Siltronic shoreline wells:
Additionally, it is understood that once installed, new wells MW-39F, MW-40F, and MW-41F are to be sampled/analyzed for NW-TPH-Dx, NW-TPH-Gx; WDOE-EPH and WDOE-VPH; analyses that have already been incorporated into the Fill WBZ Trench SAP/QAPP, where installation and sampling of these wells is described.
Based on our discussion yesterday, NW Natural withdraws our September 5, 2014 statement that the TPH fractionization testing will be a one-time only occurrence. Instead, NW Natural will evaluate the usability of the TPH fraction data for risk assessment purposes after the data from this event are available, with recommendations for inclusion in a subsequent event to be made at that time. Further, and in light of the known limitations with regard to laboratory detection limits relating to the WDOE EPH and VPH Methods, NW Natural will evaluate the data once available and will make a determination as to how any such data will best be compared to screening levels presented by DEQ.
NW Natural plans to mobilize for the next sampling event as soon as possible after DEQ concurrence is received. Coordination with a pending "Phase 1 Step 6" test of the groundwater extraction system will be necessary so that the two activities do not interfere. As such, and depending on schedule, the groundwater monitoring event may be initiated prior to the Phase 1 Step 6 testing, but may need to be paused for the duration of the Phase 1 testing, to be completed as soon as possible after conclusion of the Phase 1 Step 6 testing.
We look forward to your written approval of the proposal for inclusion of TPH testing in the pending groundwater monitoring event, dated September 5, 2014, as amended by this response and the attached table.
Regards,
-Rob
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Rob Ede, R.G. * robe@hahnenv.com
Hahn and Associates, Inc.
Environmental Consultants
434 NW 6th Avenue, Suite 203
Portland, Oregon 97209-3651
Phone: 503.796.0717 * Facsimile: 503.227.2209