10/29: Project after completion. View of quarry spall where the tar was removed in the foreground, fringe cap nearshore and the railroad bridge in the background. Looking upriver. |
10/29: Project after completion. View of fringe cap (foreground) with the St. John's bridge in the background. Looking downriver. |
10/27: Placement of near shore "fringe cap" outside of tar deposit removal area. The fringe cap was placed to cover any disturbed tar materials as a temporary measure until broader site cleanup is conducted. |
10/26: View of GASCO site looking downriver; St. John's bridge is in the background. Darker section of shoreline is rock armor material. Rock is being placed over sand and the organoclay to minimize remaining tar material dissolution or erosion. |
10/25: Placement of sand on shore to armor remaining tar deposits that extend up into the riverbank. Looking downriver (St. John's bridge in the background). |
10/25: Armor placement on shore--bucket is about to drop material. Looking downriver. |
10/25: View of barge in foreground with sand and rock armor material for placement at the site. |
10/24: Cap after placement in the near shore area looking downriver. |
10/24: Cap after placement in the near shore area looking downriver. |
10/23: A diver assists in the placement of the mats and cover with sand cap material. Photo is looking upriver. |
10/23: Organoclay mats are placed near shore where seepage was observed to temporarily contain any free oils that come out of the sediments or uplands. |
10/22: Silt curtain removal. After the cap was placed over the dredge prism, the silt curtain was taken down to make way for fringe area capping that extends throughout the entire containment area. |
10/21: Beginning cap placement. Though the contiguous tar deposit is gone, the bottom sediments are still contaminated from years of tar discharge. Clean sand is placed over the still contaminated bottom until a final site remedy is decided upon. |
10/19: Final grade dredging proceeding in areas identified above design target depths. Environmental bucket is at the center of the photo, about to exit the water column. |
10/18: Sample PD 12--See map on GASCO main page to see where this sample was taken. This was one of the post-dredge samples taken below the tar mass that was removed. As suspected, sediment below the tar mass shows visible contamination. This sample has evidence of non-aqueous phase liquid similar to that seen in upland wells. |
10/16: View of near shore tar mass that remains due to inaccessibility (under or behind dock area). A deeper section is visible at the left, bottom of the photo where material on the bottom has sloughed into the dredge prism. |
10/15: View of the GASCO site nearing completion. |
10/14: Barge door after additional anchoring/weighting was added to close the gap between the door and the remainder of the containment curtain. |
10/14: A gap in the barge access silt curtain "door" at the site was identified and brought it to the attention of NW Natural and EPA. This was corrected within hours of when it was first noted. |
10/13: View of inshore area where additional tar removal was directed on 10/5 (see photo below dated 10/4.) |
10/12: Dredging taking place in the channel side of the dredge prism (outer containment area). The bubble curtain had to be turned off at this point due to the bubbles causing the silt curtain to float towards the surface. The environmental bucket is being used again in the photo above. As harder material is encountered, operators switch back to the clam shell bucket which is heavier and better able to penetrate sediments; where softer material is encountered, the lighter environmental bucket is used which better contains disturbed sediments. |
10/11: Removal of the inner silt curtain took place slowly once the outer containment boom was in place. |
View of the inner and outer containment silt curtains with the St. John's Bridge in the background. |
10/9: Placement of the outer containment silt curtain along C-D transect. A second curtain containment system must be set up to dredge the second phase of the prism, which is toward the channel and in deeper water. Since for this portion the silt curtain cannot be placed surface to bottom, a "bedload baffle" will also be put in place to hold back material moving along the bottom of the dredge prism. |
10/9: In shore area of dredge prism after removal, with an oil absorbent boom draped across it. The railroad bridge is visible in the background (upriver). |
10/5: Near shore close up of the edge of the dredge prism. A sheen is observable coming from the tar lense area which could be lighter fractions of the tar coming off into the water, or a slow oil seep. |
10/5: Long view looking upriver at the near shore area after tar from the prism has been dredged. The white line is an oil sorbent boom used to soak up oils being discharged from remaining riverbank tar. |
10/4: Tar lense of material (black) with rock/soil overburden (brown). This material likely extends into the uplands where depths of tar extend up to 60 feet deep in places. This and the tar deposit itself were originally part of an overflow ditch from the upland tar ponds. |
10/4: tar deposit in the area between the sorbent pads that is outside the dredge prism. EPA directed removal of this material on 10/5 after DEQ personnel noted its presence. |
Overview of inshore dredge cut. An oil sheen is present at the right; oil boom at the center of the photo. The cap in water will extend over this cut to ensure it does not slough into the river. Also, cap amendments will be required to absorb oil discharges coming from the uplands on a temporary basis, until an overall site remedy is put in place. |
10/4: Fourth step; water is passed through carbon filter cannisters in series (water through one, then through the other). Water is subsequently discharged to the area inside the silt curtain. The second in line filter was added as a result of pre and post cannister treatment sampling showing that acute concentrations of contaminants (see water quality reports posted in the GASCO Removal Updates section) were still coming out of a single carbon cannister unit. |
Third step: water is passed through bag filters to remove further particulates. |
Second step: water is passed through an oil/water separator to remove any oil and floatable material. |
10/4: First step: Photo of water catchment on the barge where initial pumping and filtering takes place during dewatering of tar material. This is the first step of dewatering water treatment. This tar material must be dewatered to make the tar material suitable for Subtitle C disposal. |
10/3: In shore extent of dredging as it moves toward the dock (compare to 9/30, 9/29). |
9/30: Close up of inshore dredging area. |
9/30: Continuing inshore tar dredging. A sheen is visible along the shoreline. |
9/29: Transload site. The environmental bucket is offloading the haul barge. Hoppers have been added (right side) to stage material and ensure that is adequately dried before sending to the Subtitle C facility. |
Trackhoe moving material from hoppers staging areas to trucks. |
9/29: Near shore tar excavation. Picture shows a U-shaped area where tar was removed on 9/29. |
Clam shell bucket removing near shore tar. Heavy sheening is noticeable during this part of the excavation. |
Seep of oily liquid that began once this near shore area was excavated (non-aqueous phase liquid or NAPL). Upland of the tar deposit up to 4 feet of NAPL is present at some well locations near the riverbank. |
9/27: Photo showing the silt curtain with a geofabric patch over a tear. Dredging had to be shut down for approximately one hour when a rip was discovered in the silt curtain by a routine diver inspection. No specific cause was identified, but it is suspected that the rise and fall of the curtain with the tide may have 'hung up' the curtain on a sharp object on the bottom, causing the rip. Diver inspections will continue at an increased frequency as a result. |
View of the tar deposit dredge cut, looking inshore from the FAMM loading dock. |
Close up of the dredge cut in shore. Note the sheen coming off the tar material. |
9/21: View of GASCO removal from channel. The haul barge, being loaded, is in the foreground. |
9/21: Dive platform at center near the haul barge (right). View is from the channel. |
9/22: View of haul barge during offloading (near empty). The tarp is used to contain windblown dusts during transport.. |
9/19: Barge dewatering treatment system at left of center. Water is fed through carbon (blue cannister) to remove PAH contaminants and particles before returning to the inside of the silt curtain containment. This extra step was added after water quality exceedances were discovered through routine monitoring. The changeout schedule was increased on 9/29 based on pre and post treatment monitoring data. |
View of the GASCO removal from the railroad bridge. |
View of GASCO site from the channel, upriver. |
9/16: Offloading the haul barge at the transload facility. Bucket is swinging from the barge to the truck hopper where the load will be dropped into the truck bed. |
Bucket is "grabbing" material from the haul barge to swing to the truck. Note the spill tarp in foreground to contain drips from the bucket. |
Close up of waste material in the haul barge, after dewatering agent has been added to the tar. |
9/14: Loading material from the barge to trucks (transload) for disposal at the Subtitle C Waste Management Facility in Arlington. |
Tarped area under hopper where trucks will receive tar to take to the landfill. |
View of the haul barge with tar aboard, awaiting loadout via a clamshell bucket to trucks. Workers are mixing the material to ensure consistent water content. |
Dredging on 9/13: Dredging continues in the nearshore area. Once this area is removed and the water is deepened, the barge will be able to remove the farthest inshore tar. |
Piling removal in nearshore areas. |
Dredge bucket moving toward barge to unload. |
Clamshell bucket depositing material on the barge. |
Commercial diver exiting the water after setting an anchor point. |  |
September 8: View of dredging from St. Johns bridge sidewalk. The dredge bucket about to unload onto the barge for initial dewatering (right). |
Close up of dredge bucket (clam shell type is now being used due to refusal encountered). The black spill apron in the foreground ensures any spillage is returned inside the silt curtain enclosure. |
Close up of the silt curtain. From the murky color, higher turbitidy is visually observable inside the silt curtain. |
September 5: Seining fish out of the removal area. Fish captured included: 94 shad, 2 starry flounders, 45 small-mouth bass, 1 large-mouth bass, 19 perch, 1 larval shrimp, 1 crayfish and 1 sculpin. No endangered fish observed. |
September 7: All barges on site and ready to begin dredging. |
September 7: Second bucket of dredge material removed from the tar deposit being placed on a barge with an environmental bucket.
Video: Bucket Leaving Water (3.8 MB, Windows Media Player File, 11 seconds)
Bucket Placement on Barge (4.6 MB, Windows Media Player file, 14 seconds)
To get Windows Media Player, Click Here. |
August 30: Deployment of the bubble curtain. |
Deployment of the silt curtain along transect A to B. |
September 2: Bedload baffle deployment |
August 25: Initial deployment of silt curtain (still rolled up). |
Pressurized air line in foreground which runs from a compressor on shore to the "bubble curtain" which will be used in water to surround the removal area with air bubbles, thereby limiting fish entry. |
Close up of a portion of the silt curtain (black) and float (yellow). The silt curtain is designed to control offsite releases of particles stirred up by the dredge. Anchors and the float keep the silt curtain upright in the water column. |
August 24: View of divers (dressed in polluted water protective equipment, including surface supplied air and a full helmet) placing anchors for the inner containment silt curtain. Due to the nature of the removal project, and combined sewer overflows in the area, divers are receiving a full rinse after returning to the vessel, before breaking the seals on their protective equipment. |
Barge and derrick placing anchors on the bottom in preparation for dredging. |
View of project site with silt curtain anchors (inner containment) marked with buoys in foreground / St. Johns bridge in the background. |