Volunteers Pitch In to Repair Damage from Spring Storms
June 2010
For weeks, residents and visitors have glumly observed the declining water level in the Pond, kept low ever since punishing March storms punched
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| April 20: It took two tons of concrete to fill this cavern under the spillway. |
sinkholes in the Foster's Pond Dam and exposed a large hollow space beneath the dam's concrete spillway. The Corporation's engineering consultant warned that the dam could fail unless the 2009-2010 winter drawdown was extended, allowing repairs to be made with as little water as possible lapping at the dam.
In April, volunteers were able to repair the spillway - first sledgehammering through the concrete cover to expose the full extent of the cavern below, probably the result of decades of settling of the rocks that form the core of the 150-year-old dam. Two tons of concrete were mixed by hand and poured into the void.
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| June 17: Scott Fumicello and volunteers excavate the sinkholes. |
But repairing the sinkholes, and the channels through the dam that had caused them, had to await low water and dry weather. To residents depending on shallow wells for the household water, the wait seemed like an eternity.
Finally, in mid-June, the work began. Volunteers - led by landscaper and master mason Scott Fumicello - excavated the area on the southerly crest of the dam where the sinkholes had developed. Using a mini-excavator, they were able to get down to the water line, exposing the source of the damaging leaks.
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| June 19: A coffer dam (left) exposed erosion under the walls on the southerly side of the dam. Area residents Dave Adilman (with shovel) and Bob Pincus spread concrete to plug leaks which caused sinkholes. Photos by John Lugus. |
To plug the leaks securely, a coffer dam - consisting of about 30 handpacked sandbags - was constructed in front of the dam's sluiceway, creating a dry area into which concrete could be poured to fill eroded spaces under and around the massive granite blocks on the face of the sluiceway walls.
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| June 19: Seven cubic yards of concrete, pumped from equipment on Rattlesnake Hill Road, fortified the dam's most vulnerable flanks. Photo by John Lugus. |
More concrete was poured behind the granite blocks on the "wing walls" on both sides of the spillway. This concrete will stabilize the walls, and prevent heaving from winter frosts, which can create channels into which water can flow.
A concrete truck and a pump truck had to be brought in to pour the seven cubic yards of concrete needed to complete the work.
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| June 24: Concrete (top) now fortifies more of the dam. Note the patch in the middle of the spillway, which alone took two tons of concrete. The finishing touches (right) include several tons of crushed rock added to both embankments, and a new layer of loam on the crest, which has also been re-seeded. A stop log has been inserted in the sluiceway, but how fast the Pond rises will depend on rainfall. |
Several tons of crushed rock were added to both sides of the dam's embankments, providing additional protection against erosion.
Then, the crest of the dam was re-loamed and re-seeded, to restore the dam's grass cover. Grass is an essential component of erosion control on an earthen dam.
Finally, the first stop-log was inserted in the dam's narrow sluiceway on June 20, beginning the process of refilling the Pond. But with little water flowing into the Pond, raising the water level will depend on Mother Nature sending some heavy rains.
2nd March Storm More Damaging Than 1st
April 2010
Just as it seemed that the Foster's Pond Dam had dodged a bullet from torrential rains in mid-March, a second storm swept through at the end of the month, causing serious damage to the 150-year-old structure.
As several more inches of rain fell on March 29-30, on top of the deluge
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| April 2: This sinkhole, which appeared during the mid-March storm as a small depression, collapsed in the late-March rain. This photo is from the GEI report. |
that hit two weeks earlier, a small sinkhole that had appeared in the first storm collapsed, succumbing to a current estimated at several gallons a minute boring through the dam adjacent to the two-foot wide sluiceway.
With dry weather and a falling water level, more damage emerged on April 5, when the flow over the dam's 12-foot-wide spillway ended, revealing two holes in the spillway's concrete liner and one- to two-foot-deep empty chambers underneath. Those will have to be filled with concrete before the Pond can be allowed to retrun to its normal level.
On March 30, the Corporation's engineer, Lee Wooten from GEI Consultants, Inc., inspected the damage. His verdict: Some "emergency" surgery must be undertaken as quickly as possible, and permanent repairs will be required before the Pond can safely be refilled.
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| April 5: As the Pond returned to its Winter drawdown level, holes were revealed in the dam's spillway. They must be filled with concrete before the Pond is refilled. |
Prior to the first storm, the Pond had been drawn down 18 inches. The annual "winter drawdown" aims at accommodating just the sort of Spring gully-washer that March brought to the Pond.
Foster's Pond rose more than two feet during the first storm, sending water levels to the highest they've been since the Mother's Day Flood of 2006. The water level was on the way back down when Storm No. 2 struck. Even though the second storm packed less rain, and the water level remained a couple of inches below the height of the earlier storm, the additional stress on the dam resulted in substantially more damage.
In a letter e-mailed to Foster's Pond Corporation President Steve Cotton dated April 6, GEI's Wooten recommended "keeping the sluiceway open" until repairs are complete.
"Do not raise the pond as is your usual practice for the summer months" until then, Wooten wrote.
Wooten recommended plugging the leak temporarily. He specified measures for a permanent fix which will involve excavating portions of the affected area, putting in new materials, and pouring concrete.
Cotton immediately forwarded copies of Wooten's 9-page report to Town and State safety and conservation officials.
And FPC volunteers began planning the next phase of their labors to preserve the Pond's most critical asset.
Deluge Hits Andover, But Dam Takes It in Stride
March 2010
Mother Nature dropped six to eight inches of rain on Andover in the 48 hours before St. Patrick's Day, shutting roads and flooding low-lying areas. But the Foster's Pond Dam - restored in 2007 to handle just such a challenge - withstood a two-foot rise in the Pond's water level and sustained only minor damage.
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March 15: As torrential rains raise the Pond by two feet, water surging into the stilling basin below the Foster's Pond Dam completely fills the two thirty-six inch culverts running under Rattlesnake Hill Road. |
If anyone was wondering why the Corporation lowers the Pond each Fall, the unnamed March storm of 2010 provided a dramatic lesson. Before the rains came, the Pond was down about 18 inches below the lip of the dam's spillway, leaving room to accommodate heavy Spring rains and melting snow without putting excess pressure on the dam. As the rains pelted down, Foster's Pond rose a couple of feet in just 24 hours, even with all three "stop logs" removed from the dam's narrow sluiceway.
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| March 9: Before the storm, the Pond had been drawn down 18 inches below the lip of the spillway. Note how much of the granite wall on the left side of the dam is exposed. |
March 15: The dramatic rise in the water level - about two feet in 24 hours - now covers the spillway and the platform just to the left of the spillway. Only the top three courses of granite blocks are visible on the wall, and one is partially under water. |
Water surging over the dam's 12-foot-wide spillway turned the "stilling basin" at the foot of the dam into a devil's cauldron of frothing water. As the flow peaked, the tops of the twin 36-inch culverts under Rattlesnake Hill Road were barely visible.
Water from Foster's Pond flows under the road to a huge expanse of wetlands. They filled to capacity, taking on the appearance of lakes and flooding Woburn Street in two places.
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| March 15: At its peak, the water level was just a few inches short of emptying through the emergency spillway (foreground). That's the safety valve which ensures the Pond won't get high enough to overtop the dam. |
The dam has a primitive mechanism for lowering the water level of the Pond. Three ten-inch tall boards are removed, one after the other, from the sluiceway just to the right of the dam's spillway. Operating under an Order of Conditions approved by the Andover Conservation Commission, the Corporation is permitted to begin the drawdown process in November, completing the adjustment by early December, before the Pond freezes. The idea is to allow for just what happened earlier this week: a huge influx of water in the Spring without overwhelming the 150-year-old dam. The water level is kept low - about a foot-and-a-half below the lip of the spillway - until mid-May, when the snow has melted and the ground has thawed, diminishing the danger of flooding.
This week's deluge was reminiscent of the Mother's Day flood of 2006. Foster's Pond had just been refilled when the rains came that May. The dam overtopped, causing severe damage. After a State-mandated safety inspection found the need for significant work, volunteers put in hundreds of hours restoring the dam and increasing its safety.
One notable improvement to the dam after the '06 flood was the restoration of the
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| March 17: High waters and strong currents carried a child's paddleboat to the sluicway. Volunteers managed to free the waterlogged craft. |
emergency spillway. That sloping pathway to the left of the dam, which neighbors and visitors use to launch canoes and boats into the Pond, is actually engineered to handle extreme water levels. Before the Pond rises high enough to overtop the dam again, water will flow over the emergency spillway, which is lined with a geosynthetic cloth to prevent erosion.
After this week's storm, water lapped just a few inches below the crest of the emergency spillway but never rose high enough to begin flowing down the grassy slope.
As well as the dam performed, it did not escape unscathed. A couple of long-standing seepage areas were enlarged, and a one-foot diameter sinkhole developed near the sluiceway. The Corporation's engineering consultant will inspect the dam at the end of the month, and volunteers will then go to work patching up the damaged spots.
2009-10 Drawdown Beats the Freeze
May 2009
The 2009-10 winter drawdown, begun in mid-November, brought the Pond's water level to its winter target just as Mother Nature dropped the temperature and covered the surface with a layer of skim ice.
That's exactly the way the process is supposed to work, letting aquatic beasties adjust to the Pond's shrinking
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| December12: Water dances through the spillway, with Pond at its target level for the winter. |
acreage before the ground freezes around them.
Annual drawdowns kill nuisance vegetation along the shoreline, but the primary purpose for them is to give the Pond added capacity to handle Spring runoff and snow melt without overtopping the dam. The maximum the Pond can be lowered is 18 inches below the lip of the dam's 12-foot wide spillway.
The winter drawdowns are conducted by the Foster's Pond Corporation pursuant to an Order of Conditions approved by the Andover Conservation Commission. On December 1, the Commission voted unanimously to extend the Order - which also covers the FPC's weed management program - for three years, through 2012.
As usual, the Pond's beavers were not happy about the drawdown, stuffing the dam's sluiceway with logs and brush every night until the skim ice got in their way. This year, they introduced a new building material in their quest, somehow jamming a muck-encrusted fiberglass ski into the sluiceway's narrow opening.
Volunteers - led by landscaper Scott Fumicello - this Fall reinforced the embankment on the dam with two layers of crushed stone. The stone holds in place a layer of industrial fabric which prevents erosion of the dam's clay fill. Fumicello has been instrumental in restoring the dam.
Spring Showers Gently Refill Pond
May 2009
April showers brought not only May flowers but also a mid-May refill of Foster's Pond, raising the water level just enough to start the picture-postcard cascade over the spillway of the Foster's Pond Dam. This year's gradual refill was right on schedule, gently restoring the 18-inch drop achieved by the 2008-9 annual winter drawdown.
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| May 18: With all three stoplogs in place in the narrow sluiceway (right) of the Foster's Pond Dam, water cascades over the spillway after the Pond returns to its "normal" level. |
The refill began on April 17, when the first of three "stop logs" was inserted in the dam's narrow sluiceway. It took just under a month, as the remaining stop logs were put in place, for the refill to restore the water level to "normal" for this time of year. It also took 5.75 inches of rain, most of which splashed down in late April.
This is the fourth year in a row, since the sluiceway was restored, that the Pond has been drawn down for the winter and refilled in the spring, and the process is becoming routine. The aim is to prevent "overtopping" of the dam if heavy spring rains combine with snow melt and saturated soil to produce flooding conditions - as happened in 2006.
Refill Begins, Ending Drawdown
April 2009
As the last traces of winter snow vanished from around the Pond, the 2008-9 winter drawdown shifted into reverse. On April 17, the first of three "stop logs" was inserted in the narrow sluiceway of the Foster's Pond Dam, beginning the process of refilling the Pond for the summer.
The water level will be brought up gradually over the next month, until flow is restored over the twelve-foot-wide spillway, the picturesque waterfall of the 150-year-old dam. Lowering the water over the winter is a safety measure, aimed at providing additional capacity for the Pond to accommodate melting snow and spring rains without "overtopping" the dam - as last happened during the Mother's Day flood of 2006.
In the meantime, the Pond's beavers have been eager to see an end to the drawdown, stuffing branches into the sluiceway of the dam
without waiting for humans to raise the water level. That mound of branches to the left of the accessway is all material that beavers have brought to the dam. It must periodically be removed from the sluiceway and stored in a safe place, then carted away.
2008-9 Winter Drawdown Gets Underway
November 2008
With icy weather suddenly in the forecast, the annual Winter drawdown of Foster's Pond began November 16. It is expected to take about two weeks to lower the water level about 18 inches below the lip of the dam's spillway.
This is the fourth year in a row that the Foster's Pond Corporation has drawn down the Pond. The dam's
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| November 16: Water gushes through the Foster's Pond Dam's narrow sluiceway (right), after the removal of two of the "stop logs" which control the water level. The 18" drawdown will take about two weeks. |
narrow sluiceway - adjacent to the wider spillway over which water cascades during most of the year - was restored in 2005 to allow some control over the water level in the Pond. Decades ago, a pipe and valve system made it possible to draw the Pond down several feet, but the pipe collapsed in the 1970's and has since been covered in concrete.
The drawdown is largely a safety measure, allowing the Pond to absorb melting ice and seasonal run-offs in the Spring without "overtopping" the 150-year-old dam. Overtopping, which last occurred during the Mother's Day flood of 2006 - can wreak havoc on an earthen dam.
Drawdowns also contribute to weed control, allowing Mother Nature to kill such nuisance weeds as fanwort growing close to shore in sediments exposed to freezing during the winter.
The water level is controlled by removing "stop logs" in the sluiceway. Two of the 10-inch tall boards have been removed to start the drawdown. The third board will be removed in about a week. The boards will be re-inserted in the sluiceway next April, bringing the water level back to normal.
Rebuilt Wall Erases Last Sign of '06 Flood
October 2008
The Mother's Day Flood of 2006 inflicted severe wounds on the Foster's Pond Dam, when the rain-swollen Pond overtopped the dam's earthen crest. Until recently, the Corporation has focused on the safety-related repairs that have turned the 150-year-old structure into a grassy community park while earning it the State's second-highest safety rating.
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| The retaining wall around the "stilling basin" at the foot of the dam underwent repairs in October. |
But over the last couple of months, local resident Scott Fumicello - the master mason and landscaper who has volunteered countless hours to restore the dam - has been able to focus on parts of the dam that had been hard-hit by the storm but weren't deemed quite as critical by inspectors.
This month, Scott rebuilt portions of a retaining wall that surrounds the "stilling basin" at the foot of the dam. Nearly a third of the stone wall had been washed out when the dam overtopped. When very large volumes of water are running over the dam's 12-foot-wide spillway, the retaining wall channels the flow into the 36-inch culverts which run under Rattlesnake Hill Road.
One precaution against overtopping is the annual Winter drawdown of Foster's Pond. The drawdown gives the Pond added capacity to accommodate build-ups of snow and ice over the Winter, so that the Spring
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| Retaining wall (right) as it appeared last year, before it was repaired. |
thaw does not result in more water than the dam can handle.
This year's drawdown is slated to begin on November 14. It will take about two weeks to lower the Pond 18 inches below the lip of the spillway, the maximum that can be achieved with the current configuration of the dam.
The Corporation, as required by the Order of Conditions which regulates the drawdown, has sent notices to a dozen homeowners with shallow wells, letting them know who to call if their wells run dry during the drawdown. No well-owner has had a problem with drawdowns over the last three years, when the annual practice resumed following a lapse of some 30 years. Before that, drawdowns of more than 3 feet were regular features of Pond life, and - though there were many more shallow wells in those days - well-owners reported no problems.
State Finds Dam In Compliance
August 2008
The agency charged with overseeing the safety of Massachusetts dams has given its stamp of approval to the work done by the Foster's Pond Corporation to recondition the 150-year-old Foster's Pond Dam.
The Office of Dam Safety has issued a "Compliance Review" accepting the findings of engineers who inspected the dam last May and determined that it is in "satisfactory" condition.
The one-page notice from ODS, dated August 26, brings to an official end an ordeal that began with the Mother's Day flood of 2006, when record rains sent a torrent of water over the dam, overtopping the earthen crest and causing significant erosion. A subsequent State-ordered inspection found the dam in "poor" condition and in need of extensive work.
That led to a massive effort by volunteers to restore the structure, making it not only safer but far more beautiful. It has also been adapted as a "pocket park," open to neighbors and the general public.
A follow-up inspection in May, 2008, found the dam to be in "satisfactory" shape, a two-grade jump in the State's safety rating system. But it was still up to the Office of Dam Safety to decide whether to accept the results or the latest inspection, or whether to order further inspections or more work.
The positive ODS "Compliance Review" means that no further work on the dam is required, and that the next routine safety inspection won't be due until 2011.
Heavy July Rains Are No Problem for Rejuvenated Dam
August 2008
Unusually heavy July rains raised the level of the Pond by several inches, but the newly-restored Foster's Pond Dam had no trouble handling the high water.
The Foster's Pond weather station recorded nearly 7.8 inches of rain for the month, more than double the normal rainfall for this area. That volume of water could have caused trouble for the dam in past years. But not now. The new grass cover blanketing the crest of the dam just turned greener.
As a precaution, one stop-log was removed from the dam's sluiceway for a 24-hour period beginning July 24, when flooding conditions were predicted for parts of New England. But the flow coursing over the dam's reconditioned spillway was easily contained within its well-armored walls, providing passers-by with a picture-postcard waterfall to enjoy viewing on a hot summer's afternoon.
New Safety Inspection Gives Dam a Passing Grade
May 2008
In 2006, the Foster's Pond Dam - suffering from decades of on-and-off maintenance and the ravages of a Mother's Day flood which gouged sinkholes in its earthen crest - underwent a State-mandated safety inspection. The once-proud 150-year-old structure suffered the indignity of receiving a failing grade.
This month, in the wake of hundreds of hours of work by Foster's Pond Corporation volunteers, the dam
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| May 8: GEI engineer Lee Wooten gathers data during his re-inspection of the Foster's Pond Dam. His report gave the dam a "satisfactory" rating, a huge improvement from the "poor" mark given in November, 2006. |
was re-inspected. And this time, it passed with flying colors.
Both inspections were conducting by the same engineering firm, GEI Consultants, Inc., a nationally-recognized company based in Woburn, MA.
The 2006 inspection had rated the dam in "poor" condition, defined by State regulators as meaning that a dam has "significant structural, operation and maintenance deficiencies."
But that lousy mark is, as they say, water over the dam.
Based on its May, 2008, follow-up inspection, GEI rated the dam as "satisfactory", meaning that there are no structural deficiencies and that any operational or maintenance deficiences are only "minor". The new rating represents a two-grade jump in the State's rating system, the equivalent of a solid B - not too shabby for a 150-year-old.
"The deficiencies at Foster's Pond Dam have been corrected by a major maintenance effort that the Foster's Pond Corporation performed since the Phase I inspection" in 2006, wrote GEI vice-president R. Lee Wooten in his May 29 cover letter summarizing the re-inspection. Wooten is the engineer who conducted both inspections.
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| May 8: Snakes on a dam. While Wooten inspected, three northern water snakes sunned themselves on the newly-placed rocks below the spillway. |
Wooten's letter summarizes extensive maintenance work undertaken by the FPC, including masonry work on the crest which has increased the "safe flow capacity of the primary spillway."
That work, combined with the restoration of the emergency spillway - a trough that doubles as a boat ramp for visitors to the dam - means that the dam now has the capacity to handle the anticipated volume of a so-called 100-year-flood.
Wooten observed only one minor "deficiency" in the latest inspection, some seepage at the based of the dam below the main spillway. He recommended that the FPC monitor the seepage and watch for the development of any sinkholes.
The State's Office of Dam Safety, which regulates public and private dams in Massachusetts, ordered the inspection of all dams in 2006 after a major dam failure in Taunton. Dams receiving a rating of "poor" were required to be re-inspected at intervals until deficiences are corrected.
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| May 26: With the refill of the Pond now complete after the 2007-8 winter drawdown, water coming over the main spillway splashes onto the rocks below. If extremely heavy rains are forecast, water can be released though the sluiceway (right) to avoid "overtopping" the dam. Otherwise, water will not be released through the sluiceway until the next drawdown starts in November. |
In an order issued in February, the ODS also required the FPC to conduct a "Phase II" inspection - a much more extensive and expensive engineering study entailing detailed repair plans for deficient dams.
The GEI report recommended that, in light of the dam's improved condition, ODS modify its order so that the FPC would not need to perform a Phase II study. GEI's 36-page report was issued May 29.
Late-April Showers Raise the Pond as Drawdown Ends
April 2008
As the region basked in day after day of unseasonably warm, dry weather, the Spring refill of Foster's Pond began - but slowly.
Then came a two-day stretch of torrential rains, and water levels climbed.
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| April 22: The first stoplog was inserted in the dam's sluiceway on April 19. Three days later, when this picture was taken, rising water was beginning to splash over the top. The second stoplog went in the following day. |
The first of three stoplogs - the 10-inch-high boards which are used to control water levels in the Pond - was inserted in the narrow sluiceway of the dam on April 19.
The refill marks the end of the annual 18-inch Winter drawdown, a safety measure which gives the Pond additional capacity to absorb Spring's snowmelts and the run-off occasioned by heavy rains falling on saturated soil in the watershed.
The pace of the refill depends on the weather. With little rain, springs and streams feeding the Pond will still raise the water level, but not very fast. And gaps are purposely left between the stoplogs during the refill, so that water is always flowing into the downstream wetlands.
Within three days of insertion of the first stoplog, the Pond had risen a couple of inches, enough for water to start trickling over the top of the board.
The second stoplog was inserted on April 23. But with lower-than-normal rainfall, and dry air causing evaporation, the pace of the refill was much slower than the inch or so a day normally expected at this time of year.
Not to worry, however. A heavy rain can cause the Pond to rise several inches in one night.
And by month's end, that's just what happened. In a 30-hour period April 28-29, 2.1 inches of rain - as measured at the Foster's Pond weather station - poured down, and even before the last storm had blown through, the Pond had risen another six inches.
Too much rain is more of a hazard to the dam than too little. The Mother's Day flood of 2006, which came
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| April 23: Six tons of boulders have been placed at the foot of the dam, in the stilling basin. The aim is to break the force of water pouring over the spillway and prevent scouring, which could weaken the foundation of the dam. |
just after that year's refill, caused significant damage to the dam - though the work that has been done over the last year significantly reduces the likelihood that the dam will again be overtopped.
The balmy weather and the new "pocket park" at the dam have proved a winning combination for area residents. Whether for a young couple sitting hand in hand on the bench, or dads bringing youngsters to angle for sunfish, the dam is proving to be a tranquil and convenient spot for enjoying the Pond.
The newly-planted grass on the dam is getting some professional help this year. The Corporation has lined up Organic Soil Solutions, an organic lawn care company based in Woburn, to tend the grass in an environmentally sound way. The company is donating its services.
(For more information on landscaping your own Pond-side property, read Lawns and Landscapes in Your Watershed, a publication of the State Department of Environmental Protection.) The grass has already received a dose of corn gluten (a natural weed suppressant and fertilizer) and an overseeding on bare spots.
Volunteers have done some additional maintenance work on the dam this Spring. As recommended by the Corporation's consulting engineers, the volunteers placed stones in the stilling basin at the foot of the dam. The aim is to dissipate the force of the water coming over dam and prevent scouring, which eventually could undermine the structure. About six tons of stones have been heaved by hand, one at a time, in the effort.
Engineers will conduct a second inspection of the dam in early May. Their first inspection, in November, 2006, rated the dam as being in "poor" condition and led to a year of extensive volunteer labor to correct deficiencies.
Pond and Temperatures Drop as Winter Sets In
December 2007
The Pond tamely followed the script for the annual winter drawdown, falling by early December to the target level of
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| December 18: The winter drawdown has lowered the Pond about 18 inches below the dam's spillway. |
about 18 inches below the spillway of the dam.
Just in time. Someone gave an early cue to Old Man Winter.
Frigid temperatures and serial snowstorms blanketed the area with mixtures of snow and ice. A new weather station on Foster's Pond recorded low temperatures of 20 degrees or below on 17 of the first 19 days of December. And only one of those days - December 12 - yielded an average temperature above freezing for the day.
State wildlife officials like to see a winter drawdown attain the low water mark before freezing weather sets in. That gives water-dependent animals a chance to adjust their burrows, move to deeper water, or do whatever else they do to prepare for winter before everything ices up. So the timing of this year's drawdown was by the book.
Meanwhile, the snow just kept on coming. And coming. Around two feet fell before the first day of winter, turning the Pond into a picture postcard. Indeed, one mother posed her family on the dam's new bench for their annual holiday picture.
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| December 18: Foster's Pond Dam blanket by the early snows. |
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drawdown was made for just such weather. Freezing temperatures will kill fanwort growing along shorelines that have been exposed by lowering the Pond. And, with the drawdown, the Pond has greater capacity to handle snow melt and spring rains without the danger of overtopping the dam.
With Restoration Complete, Drawdown Begins
November 2007
The 2007-2008 winter drawdown of Foster's Pond began November 4, with water cascading through the narrow sluiceway of the 150-year-old dam. With the Pond already several inches below its normal level for this time of year, the drawdown will bring the water down another foot or so over the next three weeks.
The annual drawdown increases the Pond's capacity to hold winter snows and spring run-off, and is aimed at averting
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| November 4: The 2007-8 winter drawdown begins. Two "stop logs' have been removed from the sluiceway. The third will come out later. |
a repeat of "overtopping" - when so much water comes over the dam that the flow cannot be contained within the concrete-lined spillway. Overtopping can seriously erode an earthen dam, and is the leading cause of catastrophic failures in such structures.
This is the third winter drawdown in as many years, part of a new regimen of lake management undertaken by the Foster's Pond Corporation, which owns the historic dam. The drawdowns, authorized by a comprehensive Order of Conditions approved by the Andover Conservation Commission, dovetail with other efforts by the Corporation to control nuisance vegetation and safeguard the ecology of the Pond.
This year's drawdown marks a major milestone in the protection of the dam, which impounds the 120-acre Pond. A year-long project to restore the dam - and turn it from a weed-entangled near-ruin into a community icon - has ended, with residents marveling at the transformation.
The dam is now far safer, with both sides of its 12-foot-wide spillway - the picturesque waterfall that carries the flow when the Pond is at its normal level - now buttressed on both sides with granite-block walls. The crest has been restored to a uniform height, with the addition of tons of clay to fill sinkholes that had developed over the years. And a new blanket of grass now covers the entire crest, replacing both the trees that sank leak-inducing tap roots into the crest and the poison ivy which discouraged maintenance.
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| October 31: The crest of the Foster's Pond Dam, now safely buffered by granite walls and crushed stone, offers a serene "pocket park" for residents and visitors. |
At the behest of engineers who inspected the dam last year, the Corporation has also restored an emergency spillway, which will allow flood waters to flow harmlessly to the side of the dam instead of over the top. The spillway will see action only in the highest of flood conditions - it will carry water only if the Pond comes up to within a foot or so of the top of the crest - but provides what could be a dam-saving relief valve in a full-blown hurricane.
The restored dam now serves a dual purpose. With the safety improvements, which include an accessway
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| Visitors can now walk easily to the crest of the dam. The emergency spillway (left of the bench) doubles as a launch ramp for canoes, kayaks, and boats powered by electric motors. Gasoline-powered engines are prohibited. |
allowing construction equipment to reach the crest when needed for maintenance or in an emergency, the dam is now easily accessible, and visitors from near and far have come to launch boats (gasoline powered motors are not allowed, but canoes, kayaks, and boats with electric motors are welcome), fish from the shoreline, or just sit and enjoy the view. The Corporation has installed a granite bench for the enjoyment of visitors to the new "pocket park."
Most of the work over the past year has been performed by volunteers, most notably Scott Fumicello, a resident mason and landscaper, assisted by FPC president Steve Cotton. The scope of the work was defined by the Corporation's engineers, GEI Consultants, Inc., of Winchester. The site plan was drawn by designer Dave Brown, a Glenwood Road resident. Many other volunteers contributed time and effort, including Dam Committee Chairman Paul Ross, Foster's Pond Road resident Will Weightman, and Rattlesnake Hill Road resident Steve Zappala.
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| On the crest of the dam, the new granite bench affords a serene vista of Foster's Pond. Rock Island, the only Town-owned island in Andover, is barely visible under the sloping tree to the left of the bench. |
Significant funding for the effort came from the Boston Foundation, which administers the Bessie Goldsmith bequest and owns the Goldsmith Woodlands, the largest property abutting the Pond. Recognizing that the magnificent shoreline views from the Goldsmith reservation depend on a healthy Pond, the Boston Foundation has been a major supporter of the Foster's Pond Corporation's efforts to protect and manage Foster's Pond.
Local companies, including Deloury Industries and Ferris Tree Service, also donated materials to the dam project.
Some finishing touches remain to be done. Additional boulders will be added to the stilling basin below the spillway, breaking the force of the waterfall to minimize erosion under Rattlesnake Hill Road.
And the Corporation is trying to raise money to erect a permanent sign at the site, replacing the temporary signs now posted on wooden stakes. The new sign will present information on the history and ecology of the Pond, as well rules for a safe visit.
Bench Added to New 'Pocket Park'
September 2007
A granite bench now adorns the new "pocket park" which is emerging on the crest of the Foster's Pond Dam.
Topped by an old slab bearing marks from the days before quarries had saws, the bench affords visitors a surprisingly comfortable spot from which to gaze at the tranquil vista of the Channel and Rock Island.
The bench, with its graceful proportions, exhibits the artistic flair of its creator, Scott
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| September, 2007: The new bench affords a tranquil view down the Channel. |
Fumicello, the Willard Circle mason and landscaper who has donated countless hours to the restoration of the 150-year-old dam. Fumicello was honored for his work at the Foster's Pond Corporation's summer meeting in August.
Granite for the bench was donated by Foster's Pond Road residents Dave Adilman and Lisa Walters.
Almost all of the work on the dam has been purely functional, the result of recommendations from the Corporation's engineer last year to prevent further overtopping. That's the term for high water exceeding the capacity of the dam's spillway and cascading over its earthen crest. The result is erosion which can threaten the catastrophic failure of an earthen dam.
With the crest on both sides of the spillway now restored, and armored by granite blocks, geotechnical fabric, and crushed stone, overtopping and erosion are much less likely. The treeless grass expanses on the crest are also designed to minimize erosion that can result from water penetrating around the woody roots of trees and bushes. And the large swale sweeping around the easterly crest of the dam is also a safety feature - an emergency spillway that will allow flood water to escape without overtopping the dam in the highest water conditions.
Many of these safety features contribute to the park-like appearance of the newly restored dam. The Corporation has opened the inviting new "pocket park" to visitors from near and far, allowing the crest to be used for fishing and the emergency spillway to double as a launching ramp for canoes, kayaks, and boats with electric trolling motors.
Litter has actually decreased at the dam since it has been opened to the public, and Foster's Pond is burnishing its reputation as a destination for serious anglers in search of feisty - and weighty - large-mouths. The anglers come from as far away as Fitchburg and New Hampshire, as well as from residences down the street. Parking is not allowed at the dam, but visitors have found on-street parking near-by. Visitors are asked to be particularly careful to stay off lawns and leave no litter behind.
Dam's East Side Nears Completion
August 2007
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| August 31 : The easterly crest of the dam reveals its finished contours. The crushed stone embankment and new granite wall protect the dam from erosion. The granite slabs just visible at the top of the photo will be used for a bench. |
The easterly crest of the Foster's Pond Dam is showing its finished contours, as the Corporation's year-long project to restore the historic structure edges toward completion.
The majestic easterly arc of the earthen dam has been restored to a height that will withstand overtopping, the major threat to dams of this type. Clay has been added to the Pond-facing slope, covered with a geotechnical fabric to keep it from washing away, and further protected from erosion by a layer of crushed stone. The top has been loamed, and will be seeded with grass, the best protective cover for earthen dams.
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| The restoration work (above) will prevent a repeat of the May, 2006, overtopping (right), when volunteers spread a makeshift barrier to slow erosion of a sinkhole on the easterly crest. |
And an important safety valve has been restored. At the direction of the Corporation's engineers, the original emergency spillway - a gully at the eastern edge of the dam - has been cleared out. The gully looks to most visitors like a boat ramp, and, indeed, boaters are invited to use it; it has been rebuilt with a lot of stone at its mouth, to minimize erosion from the launching of canoes, kayaks, and bass boats. But the real purpose of the contour is to allow flood waters to escape, without eroding the dam, in the rare storm which causes the Pond to rise to within a foot of the dam's crest.
There is still some heavy work to be done. The stilling basin, just below the dam's picturesque waterfall, has been scoured out over the decades. When water flows heavily over the dam, the basin turns into a frothing cauldron, and the turbulent water erodes the stonework under Rattlesnake Hill Road. The engineer's recommended solution: add boulders to the stilling basin and against the face of the dam, so that water pouring over the dam breaks on the rocks instead of roiling in a pool. That work is now underway.
Then there are the finishing touches - construction of a bench to provide visitors a place to sit and contemplate the view, seeding the crest with a grass cover, and finishing the slopes and the area in front of the dam with wood chips.
Volunteers are also working on a plan for a sign to provide visitors with information on the history and ecology Foster's Pond.
West Side of Dam Is Almost Finished
July 2007
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| July 25: The westerly crest of the dam, with a new grass cover atop tons of clay added to the cap. The new granite wall and crushed stone facing the Pond, are expected to prevent erosion and overtopping which periodically threatened the dam. |
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| Fall, 2004: Before the Corporation undertook to rehabilitate the dam, this is what the westerly crest looked like. Raking and weed treatments have also cleared aquatic vegetation. |
The westerly crest of the Foster's Pond Dam - for decades its most vulnerable spot - is now almost fully rehabilitated. It's lowest portion, frequently overtopped with torrents which threatened to erode the 150-year old earthen structure, has been raised nearly three feet and armored with granite blocks. Tons of new clay along the 75-foot westerly crest are protected by a facing of crushed stone, and the crest itself - once a tangle of trees, brush and poison ivy - now sports a cover of just-sprouted drought-resistant grass.
Volunteers will now focus on the easterly crest, which will mirror the new look.
Work Progressing On Dam
July 2007
Major progress has been made at the dam, with the westerly side nearing completion. On July 15, loam was spread on half the dam, showing the final contours of the portion that had in past years proved most vulnerable to overtopping.
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| July 15: Scott Fumicello uses his Bobcat to smooth new layer of loam on the westerly crest of the dam. |
The stone work has now been completed, with new granite-faced walls guarding each side of the spillway. For decades, State dam inspectors had complained that the dam's shallow, concrete-lined spillway was inadequate to handle the flow of water during occasions of normally heavy flow. With the new work, that problem has been solved.
Most of the recent work on the dam has been spearheaded by Willard Circle resident Scott Fumicello, an expert mason and landscaper who has donated time and equipment to the massive effort.
Foster's Pond Road resident Will Weightman, who maintained the dam almost single-handedly for many years, contributed a nifty solution for keeping unauthorized vehicles off the dam: he drilled a pair of anchors into the large boulders flanking the new pathway to the crest of the dam, allowing a chain to be strung across the access-way.
Grass seed was spread on the westerly crest July 17, and will be watered through 375 feet of newly-acquired hose running from the Rattlesnake Hill Road home of Dam Committee Chairman Paul Ross. Using Pond water for irrigation isn't possible this year because it contains the low concentrations of herbicide being used to treat fanwort.
The focus will turn now to the easterly side of the dam. Work is well underway to backfill the new wall with clay, bringing the easterly crest up to the same height as the western side. The easterly crest, too, will be faced with crushed stone and topped with loam. Final plans call for a granite bench and an informational sign to be added to the "pocket park."
But even unfinished, the dam is proving a popular draw. On July 15, a young visitor from Haverhill caught his very first fish there - a two-and-a-half-pound largemouth bass. After posing with his captor for a picture, the bass was allowed to return to the Pond.
2006-7 Winter Drawdown Ends Quietly
May 2007
The winter drawdown of 2006-2007 came to an end on May 22, as the third stop log was inserted into the dam. With the Pond at its "normal" level for this time of year, water flowed briskly over the dam's spillway, presenting the picture-postcard scene that has drawn visitors for 150 years.
Drawdown Inches Towards a Gentle End
May 2007
Mindful of last year's destructive May flood, managers of the Foster's Pond Dam are bringing this year's Winter drawdown to a slower end. They are keeping the water level a few inches below the lip of the dam's 12-foot wide spillway, giving the Pond some extra capacity to absorb a large storm like the one which last year sent water surging over the crest of the dam.
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| May 1: Water trickles through the sluiceway after a second "stop log" slows the outflow from Foster's Pond. The water level is expected to climb slowly - unless there's a major storm. |
Three boards called "stop logs" - inserted in the narrow sluiceway adjacent to the dam's main spillway - control the water level. When all are removed to draw the water level down for the winter, the Pond level can be dropped about 18 inches below the lower lip of the spillway. The first stop log was reinserted on April 22. The second went in on May 1. How fast the water level rises depends on the weather. In April, with the ground saturated from earlier rains, a three-inch storm raised the water level by one foot overnight.
The dam is in much better shape to withstand flood conditions than it was last year. The sinkholes caused by last year's flood have now been repaired, and both sides of the spillway have been significantly raised. The westerly side of the dam is nearly finished, awaiting only a coating of loam and seeding with drought-resistant grass. The easterly side is slated for considerably more work.
Torrential Rains Test Drawdown and New Wall
April 2007
With weather reports warning of torrential rains from an impending nor'easter, volunteers ignored blustery winds during a two-day pre-storm push to strengthen the most flood-prone section
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| April 16: The new wall fortifies what had been the lowest point in the dam. Note the water level, near the lip of the spillway. Two days earlier, the water was a foot lower. |
of the Foster's Pond Dam.
On April 13 and 14, a dedicated work crew wrestled granite slabs into place, completing a gracefully curving wall along the westerly side of the sluiceway and raising a vulnerable low area some 20 inches. They backfilled the wall with 20 tons of clay, eliminating a large sinkhole created during last May's flooding. Their efforts leveled the crest of the dam, which had dipped markedly in the area near the sluiceway. The dam is now much less likely to be overtopped when the Pond rises.
A similar wall will be constructed on the easterly side of the dam. When the work is completed, loam will be spread along the crest, which will be seeded with a grass cover. The upstream slope of the crest will be lined with a layer of clay, covered by a protective fabric weighted with crush rock. The sloping face of the crest south of the sluiceway received some of this treatment during the two-day effort, which was led by Willard Circle resident Scott Fumicello, a professional mason. He was joined by Rattlesnake Hill Road resident Steve Zappala, Dam Committee Chairman Paul Ross, and Steve Cotton.
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May 16, 2006: The dam was overtopped last May. The waterfall in the rear is flowing over the concrete-lined spillway. But the waterfall in the foreground is eroding the crest of the dam. The new work raises this portion of the dam, and protects it from overflow conditions. |
This crucial phase of the work was completed just in time. On April 15, Mother Nature delivered torrential rains on the predicted schedule, dumping some 3 inches in less than two days. By 4 p.m. on April 16, the Pond had risen about a foot, and was a fraction of an inch below the lip of the dam's main spillway. That was an astonishingly fast rise. Normally, it takes about a month to refill the Pond after the Winter drawdown. This mid-April storm refilled the 120-acre water body overnight. And that occurred with all of the "stop logs" out of the sluiceway, allowing maximum drainage the entire time.
Last year, the Pond had been refilled by May 1, leaving no room for the deluge which flooded New England two weeks later. This year, the Corporation postponed the refill, allowing workers to repair the dam during early April - and maintaining the Pond's capacity to absorb Spring floods. That strategy worked.
Safety Inspection Rates Dam "Satisfactory" 12/11
the Foster's Pond
Dam has been opened, lowering the Pond by about an inch a day.
When the water level is 18 inches below the bottom of the dam's
spillway, boards will be replaced in the sluiceway (the narrow channel
to the right of the spillway) to maintain the lower level until next
Spring.
As of November 10,
the water level was about 7" below the bottom of the spillway - about
the same level it was in September, before torrential rains filled the
Pond and sent water rushing over the dam. The aim is to lower the
Pond another 11 inches by December 1. The 18-inch drop is the
maximum allowed under the Order of Conditions - and pretty near the
limit that can be achieved with the existing sluiceway.
Volunteers have
cleared the debris, throwing it on a steadily growing heap between the
dam and Rattlesnake Hill Road. The Dam Committee will remove the
brush pile as part of its maintenance activities later this year.
The work on November 22 left the dam free of woody growth which experts
say can endanger the integrity of earthen dams. One birch tree
near the edge of the dam was left standing; the Committee plans to
return in the winter, when the tree can be dropped onto the ice for
easier removal.
the next several
months.