The city is asking for citizens’ help in protecting the Island’s sewer system. The entire sewer network, from the collection system to 18 pumping stations, is being seriously damaged by items that should not be flushed into the system.

City engineers say that adult diapers and household products are the primary culprit. Over the past several months, ‘disposable’ adult diapers — which are not intended to be flushable — have been clogging Mercer Island’s sewer pumps. While these paper and cleaning items may be biodegradable in the long run, when they are flushed through the system, they cause major back-ups. These items, along with other household products such as cleaning cloths, wipes, mop heads, heavy paper and feminine products, tangle together and eventually plug and shut down the pumps. The city is now averaging five to seven pump plugs a week.

The worst-case scenario is that a back-up at a pump station could cause raw sewage to surge out of a manhole cover and onto the street. From there, the sewage could enter the drainage system and flow into Lake Washington. Spills like this trigger automatic notification to the Washington State Department of Ecology.

The number of pump shut-downs due to this debris is growing. When a plug develops in one of the Island’s 18 pump stations, an automatic system alerts a sewer crew. The crews must disassemble the pump, often in the middle of the night, to clear the obstruction. Many crew hours are now spent clearing these pumps.

Such items can plug the homeowner’s residential side sewer pipes, which are smaller in diameter and can result in a hefty repair bill.

The proper way to dispose of these items is to place them in the garbage.

Another serious contributor to high sewer system maintenance is fats, oils and greases. These byproducts of cooking are found in such things as meat fats, cooking oil, lard, shortening butter and margarine. When these products are washed down the drain, they stick to the inside of sewer pipes (both on your property and in the streets). Over time, these waste products build up and can block an entire pipe. In-sink garbage disposals do not keep grease out of the pipes; they only shred it into smaller pieces. Commercial additives, including detergents that claim to dissolve grease, may pass the substance down the line and cause problems away from the source.

Instead of disposing of fats, oils and grease down the drain, scrape or pour them into a can and drop it off at a local biodiesel facility; or place your grease can in the trash for disposal.

The results of a grease-blocked sewer pipe can be as serious as other debris blockages:

•Sewage overflows in your home or your neighbor’s home

•Expensive and unpleasant cleanup that often must be paid for by the property owner.

•Possible contact with disease-causing organisms.

For information, contact Terry Smith, city utilities manager, at (206) 275-7812.