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Dredging  Lake Ripple

Grafton, MA

Phase 1
July-November 1999

Dredging began July 1999. Although the lake didn't smell as bad as it had many years ago, (thanks to environmental and pollution controls in recent years) it's finally getting cleaned.

Click any image for a larger view
(Please be patient when opening any of the 5 panoramas...they're large !)


sketch.jpg (30807 bytes)
This rough sketch gives an overview of the lake area,
to where the mud is pumped and how the water returns to the lake.

The Equipment

weedeater.jpg (87035 bytes)
A "weedeater" was brought in to remove many of the weeds at the beginning of the project. It was found that the lake was choked with weeds, hampering the dredging equipment by clogging it's cable pulleys.



dredgeboat.jpg (66285 bytes)
Here's the dredging equipment used. It moves slowly along a steel cable strung from shore to shore or to an anchored object so that it follows a straight path as it moves across the water.



dredger.jpg (119728 bytes)A view of the business end,

and an example of the stuff they have to deal with muck.jpg (79516 bytes)




Near the middle of the dredge boat in the suction line is an area which clogs whenever large ogjects enter it. It is cleaned often (especially near the shore) as chunks of wood and debris frequently block it.

Mostly just mud and silt is being removed.
If gravel or sand is encountered (meaning the original lake bed) it is left in place.

The Process

auger.jpg (73816 bytes)
An auger and suction pipe is mounted to a hydraulic boom which is lowered to the bottom of the lake. The auger rotates and gathers the mud towards the suction pipe in the center, just in front of it. A diesel engine provides power for the pump and pumps the mud and water at 75-80 psi. to the far side of the lake and into a large gravel basin.



outflow.jpg (92106 bytes)
At the basin, the mud settles to the bottom and the excess water flows toward the drain at the other side of the basin.



basinbottom.jpg (416477 bytes)
A LARGE 360 degree panorama taken from the center of the empty basin as the dredging began.

The basin is a large pit built to contain the mud pumped there. It is on a portion of the Grafton Lions Club property and is accessible from their driveway or a nice 15-20 minute walk along a trail beginning at the bottom of Wheeler Rd. The property along the trail belongs to the Grafton Land Trust and is part of the Gummere Wood/Marsters Preserve.


basinback.jpg (152709 bytes)
The water rises until it reaches the drain seen at the far end.



drain.jpg (59382 bytes)
Note that boards are able to be added to the drain to hold back the mud as the level rises,
yet allow the water to flow over.



pond.jpg (150538 bytes)
After the water enters the drain, it flows through a pipe into a small weedy area
(upper left in picture) before reaching the "settling pond" and the second drain seen here.



viewfromback.jpg (53587 bytes)
After reaching the second drain, the water flows through a final pipe and back into the lake.
Except, without the mud


As of Sept.7, no water had  yet overflowed into the drains
Except for the trickle of leakage, the basin had collected / absorbed everything.


In August, a second dredge was added to make sure the project completed before the lake froze over. Because of the Summer drought (and the unexpected loss of about 18" of water one night) the water level became too low in early September to support running both dredges at the same time. The call went out to get additional water from upstream Lake Quinsigamond, but was unnecessary as the drought breaking rains began that same weekend.

The following 3 photos were taken Sept.7, 1999 during the lowest water period...
just days before the rains came
(Click photos to see full size!)

lakeripplebackpanlo.JPG (192598 bytes)
A panoramic view from the back of Lake Ripple (dam and mill area to right of center)


lakerippledamlo.jpg (159841 bytes)
A panoramic view of the dam area.


viewfromrt122.jpg (76891 bytes)
View from Rte.122
Although the water depth is unknown, note the difference where it's been dredged