Hi Brian.
Thanks for submitting the sampling proposal, which I found well written and responsive to DEQ’s request. In the interest of time and the waning of the rainy season, I’m providing a few comments by section via this email, rather than responding on letterhead.
1 Introduction
1. While the shallow soil sampling proposed will be helpful for evaluating contamination potentially entrained in stormwater flowing overland and potential occupational exposures, it will not be adequate to evaluate infiltration anywhere on the site. Further, while the memo does not specify where “an area of potential stormwater infiltration” is proposed, DEQ understands from previous conversations with Parks that disposal of stormwater into the existing wetland area is being considered. DEQ notes that wetlands typically pool water due to the presence of saturated hydric soils and, therefore, are not suitable for infiltration. Please strike references to infiltration evaluation from the plan.
2.1 Topography and Drainage
2. It would be helpful to have the inlet identifying numbers referenced in this section also labeled on the figures.
3. The text indicates that ponded stormwater flows toward St Helens Rd, but “tends to flow under the concrete via eroded flow paths below the sidewalk.” This implies that rather than discharging to the street and eventually the stormwater conveyance system, most of the ponded water infiltrates into some portion of the right-of-way subsurface. Please provide additional information about the fate of this stormwater, which appears to have the potential to flow into or along the backfill of the abandoned stormwater lines toward the river.
4.1 Shallow Soil Sampling
4. DEQ appreciates the broad coverage of proposed decision units. However, the area with the highest residual PCB concentration does not seem to be covered by the proposed sampling.
a. Figure 3 shows the six decision units described in the text as well as proposed sample locations within an unnumbered decision unit between Firelane 1 and the fence along the Brazil property. Please include this unnumbered area as a decision unit, because existing data indicates residual PCBs in this area range from 8-33 mg/kg and water that ponds here can discharge to St Helens Rd near the stormwater sample point labeled “Gate Sample” on Figure 4.
b. As discussed previously, due to the extent of the removal actions completed and lack of residual PCB detections in proposed decision units 1 and 2, it is less important to obtain soil samples in these areas. If costs must be considered, DEQ’s preference is for sampling in the 7th decision unit, as described above, and forego sampling in proposed decision units 1 and 2.
4.2 Stormwater Sampling
5. The sample locations shown on Figure 4 and described in the text seem adequate to evaluate the potential for contaminants in overland flow runoff. Due to the nature of ponding and saturation occurring prior to runoff leaving the site, DEQ supports foregoing the 24 hour antecedent dry period protocol to better meet the purposes of this site-specific sampling plan.
4.3 Contingent Sediment Sampling
6. DEQ supports this approach, as needed, and anticipates needing only a brief amendment to the plan for review and approval prior to implementation.
Please provide your preferred resolution to comment 4 above and DEQ will conditionally approve the plan. Submittal of the revised plan can happen concurrent with the implementation of the plan, following DEQ’s conditional approval.
Let me know if you have questions. Thanks for completing the proposal so that sampling can get underway as soon as possible toward meeting the PPA requirement of getting permanent stormwater control features in place by October 2019.
Have a nice weekend.
--Alex
L. Alexandra Liverman
Water Quality Coordination Program Analyst
Oregon Department of Environmental Quality
700 NE Multnomah Street, Suite 600
Portland, Oregon 97232
503-229-5080
liverman.alex@deq.state.or.us
From: Marcum, Brian <Brian.Marcum@portlandoregon.gov>
Sent: Friday, April 05, 2019 4:49 PM
To: LIVERMAN Alex <liverman.alex@deq.state.or.us>; Kohlsmith, Emma <Emma.Kohlsmith@portlandoregon.gov>
Cc: Herwig, Britta <Britta.Herwig@portlandoregon.gov>; Ryals, Cindy <Cindy.Ryals@portlandoregon.gov>
Subject: Forest Park Soil and Stormwater Work Plan
Hi Alex and Emma,
Here is BES’ workplan for the soil and stormwater sampling at the Forest Park Entrance site. If you could review and provide comments and/or approval at your earliest convenience it would be appreciated. Once approved, a finalized copy will be sent for your respective files.
Thank you,
Brian Marcum, PE
Senior Engineering Associate
(he/him)
City of Portland Bureau of Environmental Services
1120 SW 5th Avenue, Room 1000, Portland, Oregon 97204
Phone: 503-823-9629 | Cell: 503-823-8672
Brian.Marcum@portlandoregon.gov
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