Plugging Waste Discharge Pipes (Ecodefense)

The following is part of a series of posts converting to html the monkeywrenching tactics in Ecodefense: A Field Guide to Monkeywrenching (3rd edition). See also the PDF of the book.

Despite the general focus of this book on wilderness defense and the general public perception that monkeywrenching is restricted to wild lands in the West, ecotage has a long and honorable tradition fighting polluting industries as well. One of the most evolved forms of monkeywrenching is plugging polluters’ discharge pipes. The following is from an expert in such matters.

The basic trick is to plug wastewater discharge pipes from various industries. Chemical, metal-working, electrical generating, mining, sewerage, and oil refining and drilling plants all discharge large amounts of wastewater. Wastewater flow rates can exceed several million gallons per day from a single source.

A single pipe can turn a vital river into a festering toxic sewer. Imagine the reaction at the plant when the foul stuff oozes back into the executive parking lot instead of into an unsuspecting river.

Choosing Targets

This is the easy part. Look in the local yellow pages for one of the facilities mentioned above. Or, walk or canoe along the local riverbank. Mark prospective targets on a map. Use a tape measure to determine the inside pipe diameter. Note the type of pipe (concrete, steel, or clay).

Sewer pipes are distinguished by gray-colored water discharges, algae growing in the pipe, rancid smells, and black ooze in sediment near the pipe. These pipes range in size from 12 to 96 inches.

Landfills leak toxic contaminants. The leacheate is often pumped into a local water body. Look for orange iron stains from the leacheate. Thin oily films will form on puddles of the leacheate. Unlike oil slicks, the films are solid, resembling the effect you get when you sprinkle talcum powder on still water.

Rainwater runoff and drainage pipes are extremely common. These pipes are at the end of natural or artificial drainage courses. They are most often 18 or 12 inches in diameter. They usually run clear, except for the first few minutes after a cloudburst begins. Then all the crap on the roads (oil and heavy metals) gets washed into the water. Many folks find storm drains a convenient place for their toxic garbage. This is a favorite trick of big auto repair shops. Plugging a rainwater runoff pipe can have a delayed but dramatic effect on a local industry or shopping mall.

Cooling water pipes are universally warm, foamy, big, and tough to plug. Generally, intakes for cooling water pipes for chemical plants should not be plugged because such a sudden blockage could result in dangerous conditions inside the plant.

Industrial waste outflows are the most noxious of all pipes. The most toxic waters from an industry run anywhere from completely clear and clean-looking to completely black. The water can turn blue litmus paper red or vice versa. If a pipe doesn’t fit one of the first four categories, and is located near a chemical, oil, metal, high tech, mining, or other plant, it’s probably a toxic discharge.

Plugging a Pipe

Small pipes 18 inches and less in diameter. The first step is to temporarily block the flow in the pipe to make your job easier. Many pipes have little or no flow during dry weather. If there is a flow, stop it up temporarily with one or more sand bags. Stuff the sand bag up the pipe as far as you can. This will give you the time you need to work.

Fill a second sand bag with a water-cement-gravel mixture and push it in up to the first sand bag. At this point you should have blocked flow from the pipe. Add a little cement around the bag to lock it in place. Cement in a few bigger rocks for good measure. (See Figure 2.)

Sometimes a bucket filled with cement and gravel will just fit into a pipe. This is especially true for 12” pipes. Add extra cement around the edges inside the pipe to ensure good anchoring. Similar objects filled with cement are available for smaller pipes (vehicle exhaust pipes, for example). Plumber supply stores have commercial pipe plugs for 2 to 8 inch pipes.

Medium pipes 2 to 5 feet in diameter. For sewer manholes, simply lift the cover and fill the manhole with sandbags. Twenty-five 60 pound bags will fill the largest ones. Far fewer bags can be used if you only stuff them up the exit pipe. The weight of the water will force a complete blockage as the manhole fills up. (See Figure 3.)

Sandbags may also be used as a temporary block while the pipe exit is blocked with bricks and cement. Cement and gravel filled bags will do if extra cement is put between the bags. This is a big operation and will require a vehicle and one to two hours work for two people.

Big pipes 5 feet and bigger in diameter. These pipes can be bricked and dammed if they are occasionally dry. There may be no or low flow times of day or year. Nail guns (watch out for firearms laws) may be used to attach strips of sheet metal onto bulkheads even if there is some flow. Or you can hammer in regular nails or special nails designed for concrete.

Look upstream for valves, gates, weirs, and intakes which may be easier to plug or gum up.

If the pipe is too big, consider homemade signs that say things like “This way to DuPont’s toxic discharge pipe.”

When you are done: Clean up all equipment. Dispose of empty containers (no fingerprints!). Camouflage your plugged pipe if possible. A pipe that’s hard to find is a pipe that’s hard to fix. Don’t return to view your handiwork. Rest assured that a well-executed pipe plug will shut down even a large operation. City-sized chemical facilities have been shut down by pipe plugs in the past.

(Examples are Dow, Midland, Michigan, 1986; Ciba Geigy, Toms River, New Jersey, 1986; Monsanto, Boston, Massachusetts, 1985.)

Helpful Hints

  1. Large utility company cooling water outfalls may discharge 500,000,000 gallons per day, but these megaplants also have much smaller yet equally vital wastewater flows — typically 1–10 MGD flows. An ecodefender can easily stop these flows. Valves and flood gates may also be vulnerable.

  2. Start small. What you learn on small pipes will help you with the big ones.

  3. Good quality, waterproof, quick-drying cement is worth its weight in gold. Anchoring cement has all these properties and it expands as it sets, too. Marine patching cement is even better, but you’ll need practice to use it well.

  4. When using cement, mix it with lots of gravel and stones. They provide cheap bulk and make the plug much tougher. If you want to ruin a company’s day for sure, add some rebar and chicken wire to your cement plugs.

  5. Plugging an intake or a bulkhead at the point where a channel flow goes underground is very effective. The flowing water will help push your plug deeper into the pipe. (See Figure 1.)

  6. These techniques are equally effective in urban, rural, and wild places.


  1. Remember that if the company wants to get rid of the crap, it must be dangerous to your health. Always use waterproof gloves and eye protection. Wear old rain gear that you can affordably discard after each job. The following parts of your body should be protected on a job:

    • Eyes — wear goggles

    • Skin — wear gloves and maybe a rain jacket

    • Lungs — gas masks are usually unnecessary, but it is prudent to work quickly in order to reduce your risk

    • Feet — wear rubber boots.

    • Mouth — wear a bandanna over your mouth to prevent liquid droplets from splashing into your mouth, especially when working around sewage.

  2. Be careful dealing with sewage discharges. They may contain harmful (to people) bacteria.

  3. Sudden blockages of chemical plant cooling water intakes may result in dangerous conditions inside the plant. Block outfalls, not cooling water in-takes

  4. Your plug may be stronger than some older concrete pipes. Plugging may cause bulkheads to collapse. Don’t stick around.

  5. Anchor cement is caustic and may burn your cuticles and sting in cuts. Always wash after using it.


Watch out for video cameras. Parallel chainlink fences spaced five feet or less apart may indicate that motion detectors are in use. Small microwave antennas may be motion detectors.

Discharge pipes are so common and lowly they are ignored by most security personnel. Unless guards are tipped off beforehand, pipes are often sitting ducks for the ecodefender.

Beware of leaving footprints in mud which is common around pipes.

For a fictional treatment of this kind of monkeywrenching, see Zodiac: The Eco-Thriller by Neal Stephenson (Atlantic Monthly Press Books, 1988).

— Armand Hammer

Field Notes

  • Flush a mixture of dry plaster and sawdust in a nylon stocking down toilets in order to block the sewer systems of objectionable developments in wild areas, such as ski resorts and National Park hotels.

  • Ocean front sewer pipes often have metal “tide gate” flaps to prevent sea-water from flooding the pipe during high tide. Lock it shut. Some tide gates already have wing nut locking mechanisms. Use them.

  • Waste pond and waste ditch overflows are easily blocked because the water pressure is working in your favor. Fill (a) sandbag(s) with mixed wet anchor cement and gravel, and stuff it in the upper end.

  • At many dumps and industrial sites you will find monitoring well caps. They are used to detect pollution underground. Do not touch them or you may endanger a site cleanup.

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