Gowanus Canal CAG Meeting
Tuesday, October 24, 2017
Mary Star of the Sea Senior Apartments, 41 1st Street
Announcements:
Doug Sarno opened the meeting at 6:35.
The September meeting summary was approved with no revisions.
Project Updates (Christos Tsiamis, EPA Remedial Project Manager)
EPA has started prep work on the pilot study, which will start a little over a month from now. They’ve opened the tunnel of the 4th street basin so equipment can get in. Today they’ve begun the sheet piling that is required to start the dredging and capping. Dredging should commence at the beginning of December, and they should complete the pilot in the spring of 2018, when for the first time in over a century a portion of the canal will have a clean bottom.
They’ll remove all the toxins that have accumulated for a century and a half and remove and replace a brand new bottom with clean material. Once we have the results from this pilot, EPA will finalize a design for the entire canal. Then we will clean out the canal from the top to the bottom.
Fourth Street Turning Basin Dredging and Capping Pilot Project
More details on the pilot study were provided by David Himmelheber of Geosyntec, the contractor working on the design. Dave presented a number of slides to give sense of what the work will look, smell, and sound like over the next few months.
Overview
- We will be dredging of all the soft contaminated sediment from the 4th Street Turning Basin of the Canal (next to Whole Foods) and installing a multilayer protective cover (cap) on the original canal bottom.
- This pilot study is a small-scale implementation to figure out the best approach for the remedy, sort of like a test drive. It is a collaboration of EPA with the Gowanus Remedial Design Group (the PRPs and Geosyntec).
- We are currently out in the field doing prep work. The full work will be performed from December 2017 to May 2018.
- In December 2016 we conducted major debris removal to allow access for the deck barge and larger barges, all of the material was screened for cultural and archaeological resources, then disposed of and recycled where possible.
Prep Work
- We will begin with initial access dredging at low tide to allow vessels to get through without moving sediment on the bottom
- Beginning tomorrow, steel sheet piling will be installed from the water side in front of existing bulkheads to support and protect existing bulkheads during dredging and capping operations, so there’s no damage or landslides. After the pilot study, the sheet piles below the waterline will be cut off so the bulkheads look the way they look now, and so the piles can’t be seen.
Pilot Study
- Will involve dredging contaminated sediments, screening sediments to remove debris, dewatering and stabilization of the sediments, treating the dredge water, and off-site disposal of the stabilized sediment.
- A multilayer cap will be installed with treatment, sand and armory elements.
- Sediment will be moved from the 4th Street Basin to the Citizens Site/Public Place, (Public Place is still occupied by Ferrara Brothers Concrete).
- Public Place will also serve as the primary staging area for support trailers and cap material storage.
Dredging
- We will use a flat level cut with an environmental dredge with sophisticated software and integrated with GIS – operator looking at the computer location for better accuracy. Material will be placed into 100-cubic-yard scows. We are looking to remove 20,000 cubic yards (all the soft sediment).
- Sediments will pass through a screen to sort out large debris. The sediment passes through the screen to a barge, while the larger material is segregated for photography and evaluation by archaeologists for cultural resources.
- Material from the access dredging is similar to the 2016 debris and is expected to include wood, tires, rope/wire, metal, concrete, gravel/riprap. These are mostly items that have been dumped in the canal. EPA noted that the community will need to take increased responsibility to prevent this behavior from happening in the cleaned canal.
Sediment processing
- The sediment will be thoroughly tested and processed, and then get mixed with cement for stabilization so it can be taken offsite. The material will be used as a daily cover for the Tullytown, Pennsylvania landfill.
- Two sediment processing sites will be used, one on site and another off site, in order to gauge the efficacy of on- versus off-site processing (with regard to sound, odor, vibrations, etc.).
Capping
- The dredging will remove about 11 feet of material and be replaced with a two-foot cap.
- The cap includes several layers of granular materials placed on native sediment after dredging to prevent the potential migration of contaminants from native sediment.
- The mutlilayer cap includes a 6-inch sand leveling layer, an 8-inch filler clay layer, a treatment layer of 4 inches (total treatment 1 foot), and a gravel armor of about 6 inches.
- The surface of the cap will be articulated concrete blocks filled with gravel (benthic layer) with good controls, placed in mats. Divers will ensure that these go in snugly and fit the contours.
Air Quality and Odor Monitoring
- 24-hour continuous air quality monitoring for Volatile Organic Compounds.
- Periodic monitoring for odor.
- Please don’t call the police when you see EPA monitoring devices because they would be destroyed.
- Instruments continuously monitor threshold (very low) minimums to make sure everyone is safe, especially those on the barges.
- Tarp covers or foam will be applied to mitigate odors.
- There will be three monitors on the Whole Foods side, two on the south side, and some additional monitors by Huntington Street.
Noise monitoring
- Some of the work will be noisy, including bulkhead sheet installation, so there are noise monitors to make sure it doesn’t exceed regulations (80 dBs sustained for 20 minutes sets off an alert, one time noise above 85 dBs creates an alert and then takes a picture to see what the noise was related to).
Vibration monitoring
- There are vibration-monitoring units on the north and south side of the basin along the bulkheads. These will compare to current conditions like existing bridge movement, and have pre- and post-construction imaging and measures to gauge damage.
Water quality
- An air curtain will bubble up air and create a current to keep the water contained on one side if there are suspended sediments so then it can be collected. At night, they will extend a more typical turbidity curtain. The turbidity monitor will continuously check what is happening so barge teams can stop or proceed.
Timeline
- Access dredging is complete.
- Bulkhead support during October, November 2017.
- Dredging from December 2017 to March 2018.
- Capping from March 2018 to May 2018.
- Demobilization May 2018.
- Work hours are weekdays 7 AM to 6 PM.
- No work will be conducted on weekends or holidays.
EPA noted that the first pilot took place during summer 2015. They tested the Record of Decision approach for native sediment containing tar, which had to be stabilized with saline water and was successful. The second pilot was in 2016 to evaluate debris removal. This is the third pilot; once it is complete EPA believes they will have everything needed to develop a process and final design for cleaning the canal.
Questions and Answers
CAG: Will there be aerosolizing? There is an air-bubble study from the PRP group in Newtown Creek.
EPA: We are familiar with that study and don’t think it applies here. There is a difference in the air curtain and an aeration system used to increase the dissolved oxygen that went half the length of the canal.
CAG: Changing attitudes about area pollution, whose jurisdiction is this? There are few no-dumping signs.
EPA: We are creating a new bottom to the canal, EPA does not have the ability to stop people from using the canal as a dump site. Perhaps a CAG group could discuss it and help implement a sense of community responsibility not to litter moving forward.
CAG: How will the sheet piles be put in? How long are they?
Geosyntec: They will be vibrated in, they are 40 to 50 feet.
CAG: When straining out debris, is there any excess water?
Geosyntec: Water will be pumped from a water treatment plant, treated, and then discharged. Depending on the level of contamination, it will be discharged back to canal.
CAG: Is there a compressor?
Geosyntec: There has been a compressor out there since October 5th. It isn’t that loud.
CAG: How often is there an archaeologist on site? Do they work with the EPA archaeologist?
EPA: John Vetter, the EPA archaeologist, completed the protocol; they monitor what is culturally significant. If something is significant, the contractor archaeologist will come to the site to investigate and then it is all sent back to EPA.
CAG: Material stabilized and sent to landfill cover, is it the top layer or intercellular?
Geosyntec: The landfill needs to be covered up at night, so it will be used for that daily cover.
CAG: Does it feel like blocks of concrete? What does it feel like?
EPA: The material looks like chunks of soil; the material is stable and without harmful compounds, but not good to touch.
CAG: Three young middle schoolers tossed trash into the canal and remarked “why would you care if you throw something in there, it’s the Gowanus Canal.” If the city dumps, everyone can dump there, so is it possible to have the city storage silos/clean up at the same time to change attitudes?
EPA: That work is on schedule, it is the prescribed path, we should both be selling different attitudes.
CAG: What height will the bulkhead piles be trimmed to and what will the edges be like?
EPA: Below the waterline, consistent with where the cap is and what is there now – no exposed sheet pile above the water so no one will get caught during recreational activity or any encounter. What you see now will be there then.
CAG: Thinking about the Riverkeeper’s patrol boat and other vessels, how far down and away from the edge will the cut bulkhead be located?
EPA: 4 to 6 inches out, the sheets protrude maybe a foot and a half, will be cut off around the same level as the cap, in terms of mean low water it is a couple feet lower – we will provide a visual section of the sheet pile/bulkheads.
CAG: Are you going to come back to the CAG with how quickly the canal could be re-contaminated after it is cleaned?
EPA: With regard to the study, the times are too short. They will take a look, but reporting pollution back there won’t be enough time to look at measurable amounts of sediment between the top and bottom of the canal. It is the kind of thing that will be measured and reported in 5-year reviews. The ROD sets up a threshold for a number of contaminants and if met, then maintenance dredging will have to happen. In 2020 NYC is obligated to move on with bank construction. The schedule of construction will take about seven years, so during that time we can expect some settling of sediment. The city has agreed they could do dredging of the materials two ways – scoop with buckets or hydraulic. Once we do it, it will be easier.
CAG: Will the monitoring data be released to the public? Are you measuring anything besides turbidity?
EPA: Just turbidity, the data is available by request. A person at the staging area is responsible for gathering it. Like vibration monitoring, a property owner affected could be given the information.
CAG: Could the Gowanus Canal Conservancy use the data for monitoring for educational use? They’re looking at eight parameters, but want the turbidity measures for certain days if possible.
EPA: We should be able to share that. EPA’s job is to warn data collectors of the dangers of the superfund site.
CAG: Will debris sorting be on site or off site – how will that be determined? Is that part of the pilot test?
Geosyntec: Primarily looking at stabilization now, during the next round of dredging sorting is occurring at a commercial facility off site. 2,500 cubic tons will be sorted there. The offsite facility will submit the data and it will be determined based on logistics moving forward.
CAG: How is the material taken offsite?
Geosyntec: By barge.
CAG: With or without permission, the CAG should make a point about cleanup progress occurring at the Gowanus and tell people not to further contaminate or believe the canal will never improve.
EPA: Yes, celebrate communities and constantly bring it up to change attitudes.
CAG: Vibration work – because the work is during the workday and schools and offices are open, is there any way to drive piles in on the weekend?
Geosyntec: Probably not; they’ll start in the middle of the basin and move to the edges and when they move toward the bridge, if it is too much, they’ll stop work. They’ll keep tabs on it and look into different approaches if it is too much vibration.
CAG: Are you going under the 3rd Avenue Bridge, or beyond the bridge?
EPA: No, there is not enough DOT information about the bridge to determine if it is possible. Geosyntec is doing an investigation, so the EPA is putting a cutoff wall 20 to 25 feet away from the bridge. Beyond the bridge is a separate piece of the canal clean up called Turning Basin 5, and there will be no action taken there at this point.
CAG: There should be community outreach, cake, and a party in May for the end of the pilot study.
Public: Where are the off-site commercial facilities that the dredged materials go to?
Geosyntec: New Jersey.
CAG: Will EPA have any public signage at the 4th Street Basin?
EPA: Whole Foods wouldn’t allow us to have a table set up on their property. Signage won’t happen. If you look at 3rd Street, there is private property on the other side. In terms of signage, it is unlikely.
Committee Reports
Archaeology
Did not meet.
Facilitation/ Outreach
The Town Hall Meeting on Gowanus is Thursday November 16 – some members are meeting on October 25th to work on planning the town hall meeting. This is the last CAG meeting before the town hall; other meeting schedules are unaffected.
Land Use
Land Use did not meet this month. The ULURP meeting for October 26th will discuss the canal and Salt Lot. We would like the City to extend the invitation to Community Board 6 and the CAG. Want to invite Kevin Clarke from DEP to CAG committee so we can understand what is happening there to formulate a response. The EPA agreed to invite the City to these meetings.
The City wants to purchase three properties, two for tanks and one for staging, so that is likely the essence of this meeting. If they aren’t able to purchase, they will probably use eminent domain. One other property, the Salt Lot, is also the location for another tank at some point.
Water Quality/Technical
No announcements.
Other Announcements
- There is a NYC DEP meeting on Wednesday, November 15th at CUNY Law, Court Square in Queens, to discuss all of the timelines and citywide issues.
- Some residents are trying to control the feral cats around Butler. If you’re interested in helping to control the cat population, please take a flyer.
- There are lots of Sandy events coming up including a march on Saturday.
The meeting adjourned at 8:05
CAG Members Present
Jerry Armer
Dave Briggs
Diane Buxbaum
Michelle de La Uz
Sean Dixon
Marlene Donnelly
Katia Kelly
Stephen Kondaks (alternate for John McGettrick)
Hildegard Link
Linda Mariano
Margaret Maugenest
Eric McClure
Christine Petro (alternate for Andrea Parker)
Peter Reich
Buddy Scotto
Brad Vogel
Maryann Young (alternate for Rita Miller)
Other Alternates
Mark Karkowski
EPA and CAG Support
Doug Sarno, CAG Facilitator
Brian Carr, EPA
Christos Tsiamis, EPA
Natalie Loney, EPA
Dave Himmelheber, Geosyntec Consultants