March 6, 2017
Please be aware that this response was received by the Coalition in February. This was before there was any drainage in the construction site. It also should be known that RTC and other federal agencies have responded that since the mercury from the breach and the existing mercury in Steamboat Creek are from the same source and therefore have the same characteristics, it cannot be determined from where the mercury increase came from. The increase was reported to be 1000% over pre-construction numbers. The Coalition sent strong language to all entities that the opposite could be true and the increase came from the breach, not Steamboat Creek. We stated strongly that they could not make their determination with any certainty. We have not received any follow up information on this issue.
Below is a summary of the events and actions related to the breach. RTC coordinated with the Corps prior to the flood and they put in place protection measures for the stockpiles and prepped the entire site for flooding. Granite Construction began preparing for the upcoming storm 1/4/2017 and continued through 1/6/2017. The work activities to prepare for the storm are listed below:
· Move construction equipment, materials, and portable toilets to high ground.
· Any material that could blow away in the wind or get washed away in flood water was either removed or secured
· All electrical systems turned off at the power poles
· The berms of clean soil surrounding the stockpiles of soil containing mercury were inspected and reinforced where needed
· Ensured BMPs remain installed correctly
· BMPs monitored on a very frequent basis throughout the weekend, day and night.
· Excavators were stationed near the Steamboat Creek drainage structures at Alexander Lake Road, Mira Loma Drive, and Pembroke Drive to remove any upstream debris that flowed into the project site and became lodged
· The project team was prepared to respond as conditions changed and monitored the conditions closely.
RTC did as requested and completed water quality sampling prior to the event. They also sampled on Monday 1/9/2017 after Steamboat Creek crested and again on 1/13/2017. The Corps was able to meet with RTC and PLPT Water Quality regarding the SEC on Wednesday 1/11/2017. The Corps viewed drone footage of the project site as did NDEP in a separate meeting with RTC The video shows the area of concern where the protective measures placed around 1 of the 12 mercury soil piles was breached and a relatively small portion of the pile did wash out. This stockpile contained Category 2 material.
The protective measures were not overtopped; the breach is theorized to have been caused by high velocities in the flood waters, which eroded part of the berm. It is theorized that the eroded soils dropped out on the South side of Mira Loma where water typically pools and sediment has an opportunity to drop out.
The RTC has done/will do the following in response:
1. Determined volume of material that washed out. The amount is estimated to be 16 cubic yards. A total of 125,000 cubic yards of soil containing mercury is already within the roadway embankment and 70,000 cubic yards are located in the twelve stockpiles. The 16 cubic yards equates to 0.0085% of the material that has been moved to date (195,000 cubic yards).
2. Sample soils in stockpile adjacent to wash out to try and determine concentration of what was washed out. As of this time, soil sampling has not been done yet. The areas are under ice or frozen.
3. Complete an assessment of ponded area by Mira Loma and other areas of deposition on the project site to determine what concentration of mercury was deposited and how to handle. A sampling plan has been proposed. Corps comments and recommendations:
· Given that Mercury is moving through the Steamboat creek system from upstream at Little Washoe Lake, how will that effect the results of sediment testing? Will it dilute the concentration? Will it increase the concentration? How will they know if what is within the site are the soils from the stockpile or the soils from the creek, or a combination thereof?
· The Corps recommended the following: ASAP, repair and improve the protection around the mercury stock piles. While only 1 appears to have breached, other protections did scour. Because the issue was not the height of the berms, but their resistance to high velocity flows, K-rail was recommended to line the berms. Concrete barrier (K rail) was placed around the stockpiles for future protection against scour on 1/17/2017.
Major clean-up has not started. The ground is frozen and/or wet. There is still floodwater located within the project site. Minor clean-up has occurred, mostly debris removal along the creek and some hand removal of debris. In some areas the construction access road has had the sediment scraped off to the side in order to allow for limited access. Work on the roadway embankment has started. North of Pembroke Drive the vast majority of it is complete and paved. The embankment within the Golf Course is complete as it relates to the soil-containing mercury in the core of the embankment and the clean soil on the slopes (edges).
North Butler Ranch also has large sections with the soil-containing mercury within the clean soil slopes. Water quality samples were taken pre-storm and the samples taken on 1/13/2017 are pending. The Corps, NDEP, and RTC are working together to interpret the sample results. It’s complex since we are dealing with naturally occurring sources, effects of flooding within the area scouring existing deposits, as well as what is on-site.
EPA looked into the stormwater permitting issue, and NDEP did issue an NPDES stormwater construction permit, which required a Stormwater Pollution Prevention Plan. NDEP and EPA worked with RTC on their sampling approach and are comfortable with it. NDEP will accompany RTC on future sampling.
Coalition Working to Protect Intersections
We should have news soon on the land use designations for the intersection of the SEC and Mira Loma. We are working with Councilman Delgado to get the four corners of the intersections designated open space to prohibit the building of 7-11's and gas stations at the intersections.
A member of our Coalition Board, who lives in Hidden Meadows, has been trying to get a meeting with County Commissioner Bob Lucey for almost a year, and have yet to get a call back. We want to discuss with him - land use issues and trucks on McCarran. Our concerns date back to his first election when he stated that he was all for development around the SEC.
Would urge others to start calling him and telling him that land around the SEC should be designated open space as it is in Critical Flood Zone 1 and is federally and locally designated flood storage areas and portions are in a FEMA Floodway. His website states that Open Space is a priority for him. Ask him to prove it. Ask him to contact the Coalition so we can discuss these issues with him personally and remind him that he is up for re-election in [email protected]
HVHA to Hold Flood Project Meeting
HVHA invites you to our meeting on Thursday, March 16, 2017, 6:30 p.m. at Hidden Valley Elementary School.
The Truckee River Flood Management Authority (Flood Project) will favor us with a multi-media presentation, updating us on our recent flood and providing a status report on plans for mitigating future flooding events. There will be a new computer simulation program that displays various flood scenarios under certain circumstances.
Please plan to attend the presentation. Invite your neighbors come along.