Wastewater Sample Collection - Moore Swab and Grab Sample Methods

Cut pieces of cotton gauze approximately 120 cm long by 15 cm wide.

Push the ends of the rectangle into an accordion shape.

Firmly tie the center with a segment of fishing line to form a butterfly shape.

Remove the manhole cover using a manhole cover hook or magnetic manhole lifter.

Tie fishing line around a clean Moore swab.

Lower the Moore swab into the open manhole until it is submerged in the wastewater stream.

Secure the other end of the fishing line so that it is easy and safe to retrieve during the next visit when the swab will be collected.

Note

Manholes vary in their configuration, so it is possible that the sampler will need to be resourceful and creative when determining how to secure the other end of the fishing line. A common approach is to use a magnetic hook. The magnet will adhere to the metal rim within the manhole cover and the fishing line can be tied to the hook. If the metal rim inside the manhole is too rusty for a solid magnetic connection or if the wastewater stream is too strong for the magnet to stay attached, a hook can also be fashioned from bendable wire (such as a wire coat hanger) and placed on a ladder rung within the manhole (Note: ladder rungs are not always inside the manholes, or they may be out of reach). If there is not a ladder rung, the sampler can use thin rope and secure it to the manhole (if there are holes) or around the manhole if holes are not present.

Return the manhole cover to its original closed position to prevent accidents or injuries from occurring.

Leave the Moore swab in the wastewater stream for 24h 0m 0s +/- 6 hours.

Using the permanent marker, label the collection bag with appropriate identifying information (e.g., manhole ID, address, nearby landmark, etc.) and collection date to ensure the sample is matched with the correct site and collection date.

Remove the manhole cover.

Retrieve the Moore swab by pulling up the fishing line.

Place the swab inside the labeled collection bag.

Cut the fishing line from the swab.

Seal the collection bag.

Place the collection bag in a cooler with ice or ice pack(s).

Return the manhole cover to its original closed position.

Store all the samples in a cooler throughout the collection day and during transport to the laboratory.

Label the collection bottle using a permanent marker and removable tape with appropriate identifying information (e.g., manhole ID, address, nearby landmark, etc.) and collection date to ensure the sample is matched with the correct site and collection date.

Remove the manhole cover using a manhole cover hook or magnetic manhole lifter.

The actual sample collection process will depend on the sampling apparatus that the group decides to use. Three different methods are provided herein for groups in different settings and with various resources: Step 22) Metal bucket and rope; Step 23) Long-handled water sample dipper; and 24) Composite sampler or peristaltic pump.

Metal bucket and rope method:

Lower the metal bucket into the manhole until it is submerged in the wastewater stream.

Slowly raise the bucket until it is out of the manhole.

Pour wastewater into a clean, autoclaved 1-L bottle.

Repeat until the 1-L bottle is full.

Wipe the inside and outside of the metal bucket with disinfectant wipes, bleach, and 70% ethanol.

Place the metal bucket in a clean bag until it is time to collect the next grab sample.

Long-handled water sample dipper or a painter’s pole rigged with a “seat” for the 1-L bottle to sit in:

Place the 1-L bottle into the seat attached to the painter’s pole.

Unscrew the lid of the 1-L bottle and set aside in a safe location where it will not accidentally fall into the manhole.

Holding the painter’s pole securely, lower the bottle into the wastewater stream until it is full.

Slowly lift the painter’s pole up out of the manhole.

Screw the lid onto the 1-L bottle until it is fully closed.

Wipe the outside of the 1-L bottle with disinfectant wipes.

Remove 1-L bottle from the seat attachment.

Disinfect the seat attached to the painter’s pole with disinfectant wipes.

Tie a bag around the end of the painter’s pole to prevent drippage during transport until it is time to collect the next grab sample.

Composite sampler or peristaltic pump

Secure clean tubing in the tubing housing of the composite sampler or peristaltic pump. Note: there should be one long end of tubing that will be lowered into the wastewater stream and one short end that will pump wastewater into the 1-L bottle.

Lower the long end of the tubing down into the wastewater stream.

Begin pumping the wastewater using the controls on the composite sampler or peristaltic pump.

Place the short end of the tubing in the 1-L bottle.

Pump until the 1-L bottle is full.

Turn off the pump using the controls.

Dispose of the tubing in a biohazard bag or safely seal the tubing in a bag and store until the next sample collection event at that particular site. Note: do not use the same tubing for a different site due to cross-contamination.

Place the labeled 1-L bottle in a cooler with ice or ice pack(s).

Return the manhole cover to its original closed position.

Store all the samples in a cooler throughout the collection day and during transport to the laboratory.