Much of the following information was found in the Environmental Impact Statement (EIS) issued by the WI DNR and the Environmental Protection Plan (EPP) issued by the US Army Corps of Engineers. This page is in=progress – we will add images and hyperlinks to make this guide easier to follow and more useful.
The Right of Way (RoW) is a permanent 50’ stretch on each side of the pipeline. It is marked by blue/white flagging or Enbridge signs that say “warning–pipeline” or “no trespassing.” There is a wider temporary construction RoW (or disturbance corridor) which is marked in the field by flagging and signs, and is mapped as the “proposed workspace” in Appendix A of the Environmental Impact Statement (EIS). All construction activity should happen within the temporary RoW boundaries.
Signage and flagging are used to tell workers where and how to work. Flags mark the boundaries of construction sites (as specified above), or may mark other underground infrastructure such as underground cables. Signs that mark the waterbody boundaries (they should display the number of corresponding waterbody from the EIS), and “no refueling” signs in wetlands tell workers they need to use secondary containment. For example, one worker told a community member that because workers are shifted from site to site so frequently, they need signs to delineate the wetland so they don’t drive through it and damage their equipment (no mention of damaging the wetland).
Safety fences are orange plastic netting used to demarcate construction areas or falling hazards. They are required around residences, at trail crossings, and around the pipeline trench.
Goalpost safety flagging is colorful overhead safety flagging required to hang over the entrances of access roads (as a height marker, so construction vehicles do not hit power lines).
Erosion control devices (ECDs) are required in construction areas once ground is broken. Their purpose is to prevent silt, mud, dirt etc from eroding off of the construction RoW. They include sandbags, sand stockings, and sediment screens (aka silt fences), which are fine plastic screening (commonly black, orange or sometimes silver) set up to filter sediments out of water or wind that passes through the construction area. They are commonly set up around open dirt, at the edge of the construction RoW, around the pipeline trench, or on slopes. If needed, sediment screens are reinforced with a second layer, such as hay bales on the down-slope side of the screens, or sandbags at the bottom. They often fail by allowing unfiltered/muddy water to flow under the bottom or over the top. The proposed ECDs are in Appendix E of the EIS.
Metal piling (or sheet piling): Metal plates that are 20-25 ft tall are jammed into the ground by cranes with specialized attachments in order to stabilize the pipeline trench. Each plate dovetails into the next one. They are used in sites where the trench may collapse due to the nature of surface material or on sites where the trench is below the water table (sites that require dewatering). The pilings are lined up in a row and then drilled into the ground one after another. This process is extremely loud. In Minnesota during the construction of Line 3, Enbridge pierced multiple groundwater aquifers, causing large volumes of groundwater to continuously flow to the surface. A map of areas likely to use sheet piling is on p 287 of the EIS.
Pipeline welding: The joints of the pipe are welded together on the ground, and then the pipe is lowered into the trench all at once. Once the pipe is in the trench, heavy pillow-like sandbags are put on it to keep it in place until the trench is refilled.
Road crossings: At junctions where heavy equipment crosses roads, workers are supposed to lay down tires to minimize damage.
Dewatering sites: Some pipeline trenches are below the water table. To enable construction, workers “de-water” the trenches with a series of continuously running pumps and pipes, essentially like bailing out a leaky boat. After the water is pumped up, it is piped to a containment structure made out of hay bales lined with sediment screens. The water filters through the screen and hay and slowly seeps back into the ground. A flow meter on the pumps measure the volume of water that is being taken up. The DNR’s Water Resources Division regulates water withdrawal and soil erosion, and writes the permit that specifies a certain volume of water allowed to be pumped out for the whole project. Pumps must sit in secondary containment (like a bin) to catch equipment leaks or spills during refueling. The hay bale containment structures must be inside of the easement, unless specified in the EIS.
Directional Drilling (or Direct Bore): A method of installing pipe by boring a tunnel rather than digging a trench. Direct bores are used to cross under roads, railroads, and some rivers where the soil is soft.
According to Enbridge in the EIS, direct bores use a tunnel boring machine (TBM) in combination with a pipe thruster to tunnel the pipeline. The TBM is attached to the front of the pipe and it is pushed forward in a shallow arc by the pipe thruster. Slurry lines (pipes) return the drilling fluid and cuttings to the surface. The pipe is installed in one pass. (EIS, p 70).
Direct boring causes very loud vibrations. Sometimes the road collapses and they need to trench through a road from the top. Workers put metal frames (different than the piling) into the cut to keep the sides of the road from collapsing.
Road bore locations are listed on p 70 of the EIS.
Blasting –The Project’s construction also involves blasting through shallow and hard bedrock using explosives in order to create the trench for the pipeline. The blasting areas are located primarily south of the Bad River Reservation, where the shallow bedrock is igneous rock, including granite. According to Enbridge, blasting would be conducted by drilling holes into the rock and detonating explosives in those holes in a sequential pattern to break the rock into fragments. Special mats are typically used over the trench during blasting to contain rock fragments where rock is particularly hard or where there is something to protect, such as an overhead utility crossing. (P. 67 of the EIS). The locations where blasting is planned are shown in Figure 2.5-3 of the EIS (p 68). See a map of the bedrock geology on p 272 of the EIS (and keep reading thru p 292 for potential effects of blasting/ HDD on the groundwater, aquifers, and artesian wells).
According to the Bad River Tribe’s “Will Effect” letter to the EPA, blasting will increase fracturing in the bedrock beyond the trench area. “Blasting has the potential to increase total suspended solids in wetlands, impact groundwater hydrology by creating new bedrock fractures which may dry up or drown wetlands, or change flow rates at seeps.“ Blasting residue will be left in the environment. The Blasting Agents as listed in the EIS will include ammonium nitrate and fuel oil (p 45, 58 of Will Effect letter).
Horizontal Directional Drilling (HDD, aka “guided bore”): Pipeline companies use HDD to drill a tunnel and insert pipes underneath water bodies, such as streams and rivers. HDD is multi-step process. First, a narrow “pilot” hole is drilled using a smaller “pilot bit”; it is enlarged during “reaming” where a much larger drillbit is pushed through the initial tunnel, and finally during “pullback,” the pre-welded oil pipe is pulled back through the hole.
During drilling, a lubricating slurry (drilling fluid or drilling mud) made of bentonite clay, water, and proprietary additives (including dawn dish soap or diesel) is circulated through the borehole from a pool adjoining the entry hole. The pool looks like a mud pit. Drill cuttings (the cut material in the tunnel) are removed by the drilling fluid. The volume of the slurry that is pumped into the ground is not measured or regulated. In many cases, large volumes of the slurry are lost in the ground or water table, and in some geologic settings, the slurry flows into cracks and pre-existing openings in the subsurface. However, only “frac-outs” (or Inadvertent Returns or IRs) are regulated violations and may stop HDD operations. During a frac-out, the slurry bursts to the surface because pressure inside the tunnel is higher than the “overburden pressure” of the ground above the tunnel. During the construction of Line 3, 12 out of 19 HDD water crossings resulted in frac-outs. Read more about frac-outs on p 320 of the EIS. At HDD sites, frac waste removal trucks are present to dispose of the slurry, and vacuum trucks and backhoes are required to be present in case of a frac-out (p 36 of the EPP).
HDD sites account for 15% of the length of the reroute.
The work areas around HDD sites are large. According to the EIS, at the beginning, or “rig side,” of the drill paths, a 200-foot by 250-foot work area is needed for equipment, drilling fluid management, and material storage. At the exit, or “pipe side”, a 150-foot by 250-foot work area is needed for equipment, drilling fluid management, and hydrostatic testing equipment. Attached to this work area would be a pipe assembly area in line with the drill path that is 100 feet wide by the length of the drill path plus 200 feet. For example, the shortest HDD drill path along the reroute is 1,774 feet, plus an additional 1,800 feet for assembly of the pullback segment of pipeline (at the pipe side).
HDD work will also take a long time. If work is conducted in 12-hour shifts, durations of 20-98 days are anticipated for each HDD crossing planned for the Line 5 relocation project (See Appendix G of the EIS). These durations may change based on their shifts. Read more about HDD on p70-74 of the EIS. HDD equipment and expertise is very specialized and expensive (at least 3x more expensive than trenching), so there is usually a much higher security and police presence at HDD sites, so that work is not monitored or interrupted. Sometimes the entire site is surrounded by 15’ tall opaque fencing to prevent monitoring and observation. Tools like drones may be useful for community oversight.
HDD sites are listed on p 69 of the EIS and are also marked on the Googlemap.
Appendices H and AH list specific site information for each HDD site.
Appendix N lists fracout (IR) mitigation and contingency plans for each of the HDD crossings.
Open Cut or Wet Trench (OC): An open trench method for crossing waterbodies used in conditions where no water is present at the crossing location. This often involves dredging (the removal of material from the bed of a waterbody). OC trenching typically takes about 24-48 hours to complete one crossing. Read more on p 65 of the EIS.
Dry Crossing (DC): Open trench method used in conditions where water is present in the waterbody; referred to as the “Dry Crossing” method. The construction zone is isolated and either a dam and pump or a flume pipe are used to route water around the isolated work area. In other words, this would likely be a dewatering site. Read more on p 66-67 of the EIS.
Typical sequence of pipeline construction: (see diagram on p 78 of the EIS):
a. Survey and Staking
b. Clearing/front-end grading (includes clear-cutting).
c. Move loose surface material (probably with a bulldozer)
d. Re-staking the centerline of the trench on the RoW
e. Installing erosion control and stabilization mats
f. Stringing pipe (placing the pipe next to the RoW, using side boom tractors, mobile cranes, or vacuum lifting equipment)
g. Field-bending pipe segments (done by a track-mounted, hydraulic pipe-bending machine)
h. Production welding (welding the pipe segments together on the side of the trench)
i. Non-destructive testing of pipe and repair, as required
(usually 10% of welds are tested in the field, using x-rays or ultrasounds).
j. Coating field welds on the pipe (the welds connecting pipe segments are coated on the outside of the pipe with an anti-corrosion coating)
k. Trenching, using a wheel ditcher
l. Trenching, using a backhoe
m. Inspection and repair of pipe coating as required
n. Inspection of the trench, potential dewatering
o. Lowering pipe into the trench (using side-boom tractors)
p. Conducting the as-built survey
q. Back-filling material into the trench (using angle blade dozers, draglines, or backhoes)
r. Hydrostatic testing (cleaning the inside of the pipe, then filling the new pipe segments with water, raising the internal pressure level, and holding that pressure to test for leaks)
s. Final tie-in (attaching the reroute pipe segments to the rest of Line 5)
t. Spread loose surface material, final grading, cleanup and site remediation
A useful list of equipment typically used can be found on p 80 of the EIS.