February Update

During the last quarter of 2015, the Remedial Design team continued to collect field data and to submit reports to EPA presenting the findings from the various design investigations. The ongoing field work has included continuation of landside drilling as part of the bulkheads evaluation. It has also included measurements to understand the chemical and physical properties of the soft sediment and installation and retrieval of noise and vibration monitoring equipment deployed for a baseline study. During this same period various data reports have been submitted to EPA presenting findings of the ongoing pre-design investigations described in prior updates.

Field work is underway to conduct bulkhead investigations by landside drilling and will continue through March.

The Gowanus Canal Design Team arranged for aerial photographs to be taken over the Gowanus Canal. The photos, taken on a clear and sunny day, were purposefully captured at low tide to show sunken vessels, areas of exposed sediments, bulkhead characteristics, and other items of interest. The photos will be used by the Team to support site staging design, access coordination, scouting upland drilling locations, assess areas of low draft and additional debris reconnaissance.

Photos from Ongoing Work

The 4th and 6th Street Turning Basins with debris and barge traffic.

Gowanus Bay with downtown Manhattan in the background.

Landside drilling near the canal continues.

March Update

The Design Team and its contractors are currently engaged in several activities on the canal. These activities are part of their ongoing effort to further study the canal and develop the remedial design. Information gained from these studies will help the United States Environmental Protection Agency (EPA) and the Design Team develop and implement a lasting remedy for the canal.

1. Temporary Dock: We are installing a floating dock northeast of Huntington Street on the western bank of the canal. The dock will be used for smaller watercraft and light field work associated with pre-design and pilot study activities within the canal.
2. Groundwater Studies: We have been and will continue to collect data to better identify locations where groundwater is seeping into the canal from beneath its floor, referred to as

Groundwater Upwelling.

We will use probes to look for abnormal water temperatures in the Sediment of the canal. The specialized probes are able to gather samples and evaluate water as deep as 3’ beneath the canal bottom. Abnormal temperatures may indicate areas where groundwater is seeping into the canal. These findings will show specific locations where divers may continue to measure the rate of groundwater upwelling.

We will perform tests to evaluate sediments on the canal floor. The findings will show the rate at which water travels through the sediments. Automated sensors also will monitor water pressure at different depths beneath the canal to gauge the amount of groundwater being discharged into it.

Ongoing Work

1. Phase 1 Non-Aqueous Phase Liquid (NAPL) Mobility Pilot Investigation: This investigation will identify areas beneath the canal floor that have higher concentrations of Non-soluble liquids. We will use specialized tools to conduct this investigation near the Citizens former Manufactured Gas Plant property and NYC Asphalt Plant Site. Work will be conducted from a barge in the canal.
2. Bulkhead Pilot Study: In February, we began an investigation into the conditions of the bulkheads that line the canal. We are evaluating various testing methods to use in determining bulkhead stability.  This will be important during field work in the canal as well as during the remedy phase. This pilot study will take place at the Citizens MGP site.

Team traveling to the working barge in 7th Street Turning Basin.

The working barge prepares for NAPL screening in 7th Street Turning Basin.

Drilling near a bulkhead at the Citizens former Manufactured Gas Plant property.

March 2016 Update

The design team is preparing for a debris removal pilot study, scheduled to begin in the summer of 2016. The pilot study will take place in the 4^th Street Turning Basin of the Gowanus Canal. The purpose of the study is to:

• Clear obstructions preventing navigational access
• Evaluate different equipment types for removing debris
• Evaluate environmental monitoring approaches to measure air and water quality

April Update

As the spring weather continues, the Design Team and its contractors remain engaged in several activities on the canal.

Upcoming Work

Sediment Studies: We will collect sediment throughout the canal for testing. These samples will guide the Design Team to determine the appropriate remedy for the corresponding area.

Measuring Non-Aqueous Phase Liquid (NAPL) Movement: We will probe the sediment near the Citizens former Manufactured Gas Plant to identify areas beneath the canal floor that have NAPL. These findings will also aid in the remedy-selection process for areas where NAPL migration may occur.

Determine Sediment Characteristics: Starting in the upper canal, we will gather over 40 sediment samples. The samples will help us learn about the sediment’s composition including the rate at which water travels through it, if it changes in volume and its density. We will use this information to develop a model that will simulate groundwater flow in different remedial design options.

Sampling Wells: We will install temporary wells within the sediment of the upper and middle reaches of the canal to evaluate Groundwater Upwelling. After gathering the samples, they will be sent to a laboratory for testing. We will use the findings to confirm results from the field-screening used for NAPL movement study.

Ongoing Work

Temporary Dock: We completed the installation of a floating dock northeast of Huntington Street on the western bank of the canal. The dock will be used for smaller watercraft and light field work associated with pre-design and pilot study activities on the canal.

Groundwater Studies: We have been and will continue to collect data to better identify locations of groundwater upwelling.

We will continue using probes to look for abnormal water temperatures in the sediment of the canal. The specialized probes are able to gather samples and evaluate water as deep as three-feet beneath the canal bottom. Abnormal temperatures may indicate areas where groundwater is seeping into the canal. These findings will show specific locations where divers may continue to measure the rate of groundwater upwelling.

We will perform tests to evaluate sediments on the canal floor. Automated sensors also will monitor water pressure at different depths beneath the canal to gauge the amount of groundwater being discharged into it.

May Update

As the spring weather continues, the Design Team and its contractors remain engaged in several activities on the canal.

Upcoming Work

Groundwater Studies: We will collect data to better characterize how groundwater enters the Canal. We will use this information in the development of future remedial design operations.

1. Groundwater Discharge Rates: Based on April’s results, we will install seepage meters in the Canal to measure the flow of water between the sediments beneath its floor and the surface water. The seepage meters will measure and record the water flow in two-day periods to provide information from multiple cycles of the tide.
2. Sediment Measurements: We will install specialized probes in the sediment of the canal to measure pressure data. This information, coupled with the seepage meter results, will help us understand the location and rate at which groundwater enters the Canal. We will also determine to what extent, if any, other materials move beneath it.
3. Hydraulic conductivity: We will use a barge-mounted drilling rig to collect water samples by installing temporary wells and sediment samples. The data will give us an overall snapshot on the rate at which water travels through the sediment throughout the Canal.  We will use this information to develop a model that will simulate groundwater flow in different remedial design options.

Drilling for Bulkhead Study: We will strategically begin drilling geotechnical borings along the Canal. Once drilled we will observe the properties of the soil and assess the structure and foundations of the existing bulkheads.

Photos from Ongoing Work

Deployment of Trident Probe into the Canal sediments. The Trident Probe technology was used as part of the effort to collect data to better identify locations where groundwater may be entering the Canal.

Sediment core processing by field team for evaluation of NAPL characteristics within the Canal.

June Update

The Design Team and its contractors remain engaged in several activities on the canal as the warm summer weather continues.

Drilling for Bulkhead Study: As part of our continuing study of bulkheads in the canal, we will strategically begin drilling borings near and along existing bulkheads of the canal. Once drilled, we will prepare the borings for tests that will help us investigate and identify the structure and foundations of the existing bulkheads.

Groundwater Studies: We will collect data to better characterize how groundwater enters the canal. We will use this information in the development of future remedial design operations.

Hydraulic Conductivity: We will use a barge-mounted drilling rig to collect water samples by installing temporary wells and taking sediment samples. The data will give us the rate at which water travels through the sediment throughout the canal. We will use this information to develop a model that will simulate groundwater flow in different remedial designs.

Sediment Studies: We will collect sediment throughout the canal for testing. These samples will guide the Design Team to determine the appropriate remedy for the corresponding area.

Determine Sediment Characteristics: The temporary wells used to collect data for the groundwater study will also be used to gather sediment samples. With the samples, we will perform tests to help us learn about its composition. This includes the rate at which water travels through it and if it changes in volume and density. We will use this information to develop a plan for dredging and the cap design.

Photos from Ongoing Work

We’re using this barge-mounted drill to collect sediment samples in core tubes.

We will test the sediment collected in core tubes, like this one shown, to develop a plan for dredging and the cap design.

July Update

The Design Team and its contractors continue working on several projects on the canal.

Drilling for Bulkhead Study: As part of EPA’s remedy, dredging will be required along existing bulkheads. Through the bulkhead study, we are learning about the structure of the existing bulkheads and assessing their stability under current conditions, so that we can understand how the bulkheads may behave during and after remediation. Field activity for this work began in June and included installation of borings and collection of soil samples. This activity is expected to continue through September.

Groundwater Studies: We will continue our groundwater studies in mid-July by installing seepage meters at many of the same locations targeted in May 2015. The devices, placed by divers into the canal sediments, will collect data over a two-day period to provide information from multiple tidal cycles. We will compare this information to the data collected in May to determine the variation in groundwater flow rates between the Canal floor and the canal surface water.

Non-Aqueous Phase Liquid (NAPL) Mobility Study: Based on the completion of the March 2015 pilot, we will begin a full-scale study of the Canal’s Non-Aqueous Phase Liquid (NAPL) movement in late July. The study will use specialized tools to better understand the presence, distribution and mobility of NAPL within the sediments.

Photos from Ongoing Work

A barge and boat used by the field team to perform the studies.

Contractors collect sediment cores from the Canal using a drilling rig.

The team prepares to lower a seepage meter into the Canal.

A diver prepares to install a seepage meter in the Canal.

August Update

The Design Team and its contractors remain engaged in several activities on or near the canal.

Drilling for Bulkhead Study

In August, the field team will conclude the first phase of canal bulkhead assessments. This work included soil sample collection, geophysical tests and boring installation. This study provides valuable information about the structure of the existing bulkheads and assesses their stability under current and anticipated future conditions. The results of the assessment will help us understand how the bulkheads may behave during and after remediation.

Non-Aqueous Phase Liquid (NAPL) Mobility Study

A full-scale study of the presence of Non-Aqueous Phase Liquid (NAPL) in the canal began in late July and will continue into October. The study will use specialized tools to assess the presence, distribution and mobility of NAPL within the sediments. We will also collect samples to determine the presence of soft versus native sediment. Results of this study will be used to confirm existing models and help refine dredge and cap designs.

Field Collections for Laboratory Studies

Throughout August we will collect samples of soft sediment, native sediment and surface water for several studies. We will use the samples to:

Compile information about sediment and determine proper ways to handle and dispose of it for future remedial design activities. We will then give the data to potential vendors to confirm if they can accept and manage the dredged sediment as well as the potential cost.

Understand the ability for bacteria within the sediment to produce gas that could move contaminants to the water in the canal. Results will be used in existing models that will help choose the best remedial design options.

Evaluate capping materials that will limit the movement of contaminants from the sediment to the surface water. We will use water and sediment samples to mimic conditions from specific parts of the canal and apply the results to the remedial cap design.

Baseline Noise and Vibration Study

Our efforts to remediate the canal will require equipment that may create noise and ground vibrations adjacent to the work area. To minimize potential effects during construction we will first implement a three-week study to establish the everyday levels of noise and vibration. Teams will set up vibration monitoring stations and noise monitor stations to collect the needed data. The results will also help us identify methods to mitigate noise and vibration from remedial activities.

Photos from Ongoing Work

The field team prepares a drill rig on the canal bank for sample collection to determine the stability of existing bulkheads along the canal.

Staff conducts one of many geophysical tests to determine the stability of existing bulkheads along the canal.

The field team sets up equipment during the NAPL mobility test conducted from a barge in the canal.

September Update

Over the past few weeks, the Design Team and its contractors continued efforts on three areas of study which began earlier this year. These three on-going projects are:

• Groundwater Studies: This month we continue with the data collection discussed in our May update. For more information, see May Update.

• NAPL Mobility Study: We are continuing with the NAPL mobility study which began in late July and it will continue into October. For more information, see our July update.
• Field Collections: We collected samples of sediment and surface water for several studies. (See August update for more detailed information.) In the coming weeks, these samples will be used to:

Compile information about sediment and determine proper ways to handle and dispose of it. We plan to give the data to potential vendors to confirm if they can accept and manage the dredged sediment as well as determine the potential cost for disposal.

Understand the ability for bacteria within the sediment to produce gas that could move contaminants to the water in the Canal. We will use the results in existing models that will help choose the best remedial design options.

Evaluate capping materials that will limit the movement of contaminants from the sediment to the surface water. We will use water and sediment samples to mimic conditions from specific parts of the canal and apply the results to the remedial cap design.

The field team uses equipment to conduct a portion of the NAPL mobility investigation in the canal.