Truesdale Lake  

South Salem, New York

October 29, 2019
by rob
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Drawdown: Report 7

These are some of the email reports and communications from Scot Evans from Truesdale Lake, James Gorman from Pond & Lake Connection, and others involved with the project. Putting selected parts up here for all to see what some of the discussion and learning is looking like.

October 29, 2019

Summary: Sunday 10/27/19 brought us the remnants of Tropical Storm OLGA, where we received 1.34 inches of rain in the twelve hours between 4 am and 4 pm.

During the 24 hours after the storm ended, the lake level rose 5″ even with all three siphons discharging a total of 1,100 CFM. Monday 10/28/19, the west 12″ siphon was observed to have stopped flowing; James Gorman was notified.

Mark Vibert of Main St recommended on the NextDoor site that we try to obtain aerial photos of the exposed lakebed during the drawdown target depth of three feet below the spillway deck. Rob Cummings responded and on Tuesday 10/15/19, he brought a borrowed drone over to my place, where we got some impressive aerial shots and video from several altitudes over the lake.

Ideal weather was enjoyed by the drone on this day before the bomb cyclone nor’easter dumped 3.34″ of rain and the lake level rose 17 inches over the next 3 days. Rob remarked that this demonstrates we’ll have no problem quickly refilling the lake this spring.

Today (Oct 29, 2019), the lake gauge is 2.0 feet below the spillway deck.
Rainfall late Oct 2019

Daily Observations
TUE 10/22/19   LG -2.0 feet     Harold Ossher observes 6″ siphon not flowing (cause unknown) and one 12″ siphon still flowing at 500 CFM
WED 10/23/19   LG -2.0 feet    0.45″ rainfall received from weak coastal low
THU 10/24/19    LG -2.0 feet    one 12″ siphon matching the inflow rate
FRI 10/25/19     LG -2.1 feet     James restarts two more siphons and all three are flowing by 0845 EDT at 1,100 CFM
SAT 10/26/19    LG -2.3 feet     Siphon discharge exceeds inflow    
SUN 10/27/19   LG -2.4 feet     TS OLGA delivers 1.34″ rain and inflow exceeds siphon discharge
MON 10/28/19   LG -2.0 feet    LLR 4.8 inches as inflow continued to exceed siphon discharge. Equilibrium achieved about 1700 EDT. West 12″ siphon stopped flowing (cause unknown).

Aerial shots of exposed lakebed:
The three islands named on the interactive map are WAXWING (north), ANT (center) and PIRATE (south).

A new set of islands became visible during the drawdown. I propose that this set be named BOAT PRANG ARCHIPELAGO or LARA’S GALAPAGOS.

Here are a few aerial photos of the lake from the many taken. I’ll post more this week on a NextDoor thread.

Newly exposed islands off of Gilbert Street houses north of the beach property.
Pirate Island (southernmost island) is shown here as Pirate Peninsula with stone wall connecting the island to the mainland.
Dormant Siphons during the September Drought.
North Cove hotspot.
South cove exposed lake bottom.
Dam, north cove, Waxwing Island.
Indian/Gilbert boatyard with dry hydrant that Skip Jahn identified and notified the fire department. They have not yet responded to lengthen the uptake head.
East side of South area and Pirate Island.
IMG_5347.jpg
Pirate Island showing exposed lake bed.

Thanks Scot for this update

Really interesting to watch how this all unfolds

Thanks again

David


Yes, thank you, and to you and Rob for the really interesting photos.
I’m not surprised the lake level rose after significant rain despite the siphons. The watershed is so big that there’s no way they can keep pace during periods of peak inflow. But once all of them are running again, the level should go down fairly quickly again.

– Harold


Love the photos! The “Galapagos” is an inspiring bird sanctuary attracting all manner of feathered friends – picture attached. 

-Lara

View of wildlife exploring and hunting on the newly exposed “Galapagos Islands” off of Gilbert Street.


October 21, 2019
by rob
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Drawdown: Report 6

These are some of the email reports and communications from Scot Evans from Truesdale Lake, James Gorman from Pond & Lake Connection, and others involved with the project. Putting selected parts up here for all to see what some of the discussion and learning is looking like.

October 21, 2019

Rain from the strong nor’easter bombogenesis (at least 24 millibar drop within 24 hours) began at 2 pm Wednesday 10/16/19 and ended just after midnight where we received 3.34”of rain. On Thursday 10/17/19, we received a small amount of wrap-around moisture with an additional 0.04” or rain.

At the beginning of the storm, the lake gauge (LG) was 2.9 feet below the spillway deck where it had remained for the past seven days. Rob Cummings also took excellent video and still shots with his drone of the exposed lakebed at this drawdown target level before the storm arrived. Will send some of his choice photos later this week.

Lake Level Rising (LLR) occurred rapidly and rose 17 inches in the 40 hours during and after the storm. This is a multiplier of 5+ times the rainfall.

Keeping in mind that the lake contour is a cone, it would take some severe calculus to convert the rise to the vertical contour of a cylinder.

James Gorman with P&LC arrived early on Friday 10/18/19 and restarted one 12” siphon and the 6” siphon at 8:30 am, which began Lake Level Lowering (LLL) as the inflow from the storm steadily decreased.

Here are the readings taken at the beginning and end of the storm, then every four, eight or sixteen hours thereafter.

10/16      1400 LG -2.9 feet datum (before rain began and followed by 3.38” rainfall from the storm)

              2400   LG  -2.5 feet or LLR     4.8 inches (Immediate Rise)

10/17      0800   LG  -2.2 feet or LLR     8.4 inches

              1200    LG  -2.0 feet or LLR  10.8 inches

              1600    LG  -1.8 feet or LLR  13.2 inches

               2400   LG  -1.6 feet or LLR  15.6 inches

10/18       0800   LG  -1.5 feet or LLR  16.8 inches (Peak Rise &
siphons energized – flowing 617 CFM)

               2400   LG  -1.5 feet or LLR  16.8 inches (remains peak
as siphons match inflow)

10/19       0800   LG  -1.6 feet or LLL  15.6 inches

               2400   LG  -1.6 feet or LLL  15.6 inches

10/20       0800   LG  -1.7 feet or LLL  14.4 inches

               2400   LG  -1.8 feet or LLL  13.2 inches (received
0.33” rain from a weak offshore nor’easter)

10/21       0800   LG  -1.8 feet or LLL  13.2 inches


Thanks Scot! This tells me we won’t have a problem refilling the lake is the spring!

-Rob


Good point, Rob! Meanwhile, it’s good to see the (reduced) siphons doing their job again. Thanks for the detailed measurements, Scot, it’s very helpful to have this tracking of what is happening.
– Harold

October 15, 2019
by rob
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Drawdown: Report 5

These are some of the email reports and communications from Scot Evans from Truesdale Lake, James Gorman from Pond & Lake Connection, and others involved with the project. Putting selected parts up here for all to see what some of the discussion and learning is looking like.

October 15, 2019

Good afternoon James, 

Starting the 6” siphon remains at your convenience. We are maintaining the target depth, where evaporation is nearly keeping up with the inflow. 

Today is 2.9 feet below the spillway. One week ago was 3.1 feet below spillway.

During the last 9 days, we received 1.03 inches of rain which was mostly absorbed by the dry ground of West Mountain and surrounding area with little inflow from the Boway Stream:

Summary: over the past two weeks with no siphons operating, we received 1.5 inches of rain with a lake level rise of 3 inches. This is a multiplier of 2 times the rainfall amount. 

We remain in drought conditions with ground absorption and evaporation the overriding factors beyond inflow. When the ground becomes saturated, we will see the multiplier rise rapidly. 


Great. Thanks for the update. I keep driving by every time I am in the area. I am scheduled to hook up the 6″ pipe on Friday. I will probably also fire up a 12″ due to the fact that we will probably get a good rain here today and tomorrow. 

In a perfect world when is the “end date” of the draw down. 

-James


James –

We finally have some impressive storm results to give you after the 3.34” of rain we received last night.

When the storm ended at midnight the lake rose 5.5 inches. 

Eight hours later, my reading just now shows a rise of 9.0 inches. 

So your plan to hook up the 6” and fire up the 6” and one 12” tomorrow is excellent. 

Your plan is great timing too, since by the time you get them flowing, I will have had four full eight hour periods after rainfall ended to report to Harold. 

-Scot

(more detail on this storm is in next report)


October 7, 2019
by rob
Comments Off on Drawdown: Report 4

Drawdown: Report 4

These are some of the email reports and communications from Scot Evans from Truesdale Lake, James Gorman from Pond & Lake Connection, and others involved with the project. Putting selected parts up here for all to see what some of the discussion and learning is looking like.

October 7, 2019

Rob and Harold:

One of the assumptions you provided for our lake to refill is 12 x Precip (rain or Snow Water Equivalent – SWE). I want to determine the best average multiplier for our lake to refill when the siphons are not operating.

The dry warm weather we’ve had is allowing the ground to absorb most of the rainfall and maintain a high evaporation rate of the lake.

Here’s my first weekly report for the drawdown where NO siphons have been operating and no water is departing over the spillway. 

The level gauge in this photo shows the top white tape as summer level when the water was at the top of the weir boards. The bottom white tape is the winter level just when the water no longer flowed over the spillway. 

Measurements for lake height.
  • Monday 9/30/19 3.3 feet below spillway 
  • Monday 10/07/19 3.1 feet below spillway

Rain we received during that week was 0.48 inches:

Precipitation record for Truesdale Lake station NY-WC-22 for first week of October 2019.

Lake level increased about 2.5 inches in one week with about 0.5 inch of rain. This is a multiplier of 5. When the ground becomes saturated and evaporation diminishes, we’ll see how close to 12 the multiplier reaches.

-Scot


Thanks, Scott, this is very interesting. It’s really important to get a reality check from actual measurements!

The Watershed tab of the latest spreadsheet indicates that, at 50% runoff, we should expect a rise of 14.8 inches per inch of rain (up from 12 because I had a low estimate of the watershed area initially). That does not take account of evaporation, and also would take some time after the rain for the water to make its way to the lake.

Rob told me that 50% is the “normal” runoff rate for our terrain, but obviously very dry or very wet seasons are not normal, and the rate changes accordingly. Plugging your measurements into the sheet shows a runoff rate of about 15%, which seems very reasonable in these circumstances.

Of course, since evaporation is not considered, the actual runoff rate is somewhat higher, but this number reflects the net effect of (rain – evaporation). And this is all a somewhat gross estimate anyway, because the area of the lake right now is considerably less than the 83 acres used in the calculations, but I think it’s good enough for us to work with.

And thanks, too, for your amazing rescue of the swan!
– Harold

September 30, 2019
by rob
Comments Off on Septic Pumping Discount for Truesdale Lake Residents

Septic Pumping Discount for Truesdale Lake Residents

We have good news: Wind River Environmental is offering a discount on septic pumping and maintenance to Truesdale Lake area residents (Wind River was known for a few years as EarthCare which was formerly Kaiser-Battistone).

Base cost for pumping septic tanks 1,000 gallons or smaller is $300.00 (regular cost is $350.00) plus an environmental disposal fee ($3.00) and a fuel fee ($31.50).

A well maintained population of septic tanks and systems in our watershed is vital to the ongoing health of Truesdale Lake.

From the Westchester County GIS system with septic pump out dates overlaid on individual properties. Some information may be out of date if a septic contractor does not fill out or submit their required paperwork. KEEP YOUR RECEIPTS so you can prove you got your tank pumped if the county comes calling!

Westchester County law requires septic systems be pumped at a minimum every 5 years. Septic pumping companies in Westchester have been required to report their pumping activities to the county since 2011. The county now has a list of the status of all septic tanks in the county. This information is publicly available online in the Westchester County GIS system.

Starting in May 2016 if you have not pumped your septic in the last 5 years, you can be fined by the county starting at a minimum of $200 and increasing from there.

screenshot-91216-537-pm
Click above image to view EPA brochure on Septic Systems

Most households need pumping done more frequently than every 5 years. Recommendations are at least every 2-3 years to maintain an optimal working septic system.

Pumping frequency depends on the number in the household and the size of the septic tank. Many lake area septic tanks are smaller size — 250 gallons or so — and need more frequent pumping. Some of the smallest need pumping once a year.

A septic system is not something you want failing at your house. It is very expensive ($10-20,000 and up) to rebuild a failed septic system, especially with limited acres to place a new field.

Contact name and number for Wind River Environmental is Isabel Lazo at 800-428-6166 ext. 4116.

If you have a question about septic systems and the law in Westchester County, call Patty Tornello-Adams at the Westchester County Department of Health at (914) 864-7360.

More information about septic systems and the law in Westchester can be found here: https://health.westchestergov.com/septic-systems

September 28, 2019
by rob
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Drawdown: Report 3

These are some of the email reports and communications from Scot Evans from Truesdale Lake, James Gorman from Pond & Lake Connection, and others involved with the project. Putting selected parts up here for all to see what some of the discussion and learning is looking like.

September 28, 2019

The lake level increased 4” since the target depth was reached on Sunday 9/22/19. So one week later, James Gorman and crew correctly restarted the two 12” siphons to keep the drawdown ahead of the rain coming in October. 

Remember this most important piece of information: For every inch of rainfall we receive, the lake level increases 12”! Remember that none of this inflow will go over the spillway until the lake fills up – at this rate. 

So, with the two 12” siphons P & LC started on Thursday, we once again reached the target depth of 3’ below spillway at noon today. It will draw down just another six inches and the siphons will shut down once again by themselves. 

After energizing the 12” siphons, James Gorman disassembled the 6” siphon intake, in order to take it back to his shop and lengthen it so that the 6” inch siphon will be started to keep up with the drawdown target depth and rainfall. He will energize one or two of the 12 inch siphons if necessary, in the event we receive significant rainfall. Pond and Lake Connection is doing everything right. 

I took pictures of the south end of the lake and attached them below. I really feel for the people at the south end especially and also at Vreeland area where the river brings in huge amounts of silt since the holding lagoon there is full and no sediment has ever been extracted as agreed, to my knowledge.

Panorama of South Cove looking east from Lake Shore Drive towards Truesdale Lake Drive.
South Cove looking northeast from Lake Shore Drive towards Truesdale Lake Drive Beach.
South Cove looking southeast from Lake Shore Drive towards Truesdale Lake Drive houses.

Also the North Cove is in similar shape. These are the critical areas that Cliff Munz circled in red on his chart.

Rather than dredge these areas it would be less expensive and make more sense to bring in big machinery to dig them out during a drawdown after necessary permits are obtained. There are several non- built properties on the lake with owners willing to take the landfill. I can secure their agreements if it comes to this. 

Neil Cutler on TLD has requested a dumpster for lake trash, but the dumpster will have to be restricted to dumping in one reserved and announced day and monitored so people don’t bring in construction debis. And I know this will happen, so I volunteer to arrange the dumpster, make the announcements and be that monitor. The best rates are from Belardinelli in Danbury. I recommend the 30 yard container. 

  • 10 yd: 1.5 tons $275 13 x 8 x 4
  • 15 yd: 2.5 tons $375 15 x 8 x 4
  • 20 yd: 3.5 tons $475 19 x 8 x 5
  • 30 yd: 4.5 tons $600 20 x 8 x 6

-Scot


September 23, 2019
by rob
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Drawdown: Report 2

These are some of the email reports and communications from Scot Evans from Truesdale Lake, James Gorman from Pond & Lake Connection, and others involved with the project. Putting selected parts up here for all to see what some of the discussion and learning is looking like.

September 23, 2019

The target depth was reached at 1 pm yesterday (sept 22) with three feet below spillway and four feet total drawn out by the siphons. As of Sunday 9/22/19 at 1:00 pm, all siphons have naturally shut down. 

Please schedule any day this week where you can lengthen the 6″ siphon to a four of five foot depth below spillway deck, so we can maintain the three foot depth as you recommended. (It needs to be four to five feet below spillway height since the vortex shut it down when it swirled 8″ above the intake.)

Detail of measurement stick with foot markings in red and spillway height in white outlined in red.
IMG_6114.jpg
Buckling of the fernco fitting and hose clamp due to the enormous and continuous water pressure in the suction pipe.

Here is a photo & video of the EAST siphon breathing air through the collapsing rubber coupling just before it shut down on Friday night.

IMG_4954.JPG
photo of the WEST intake’s whirlpool
video of the WEST intake’s whirlpool

I have pulled many fish hooks, lures, sinkers and line by cutting the geotextile fabric and dislodging the stone riprap then replacing it, so your crew should have a good suface to install the extra pipe. Here’s a summary of the drawdown progress:

  • The 1st foot of water from summer level to winter level was drawn out by three operating siphons in 60 hours.
  • The 2nd foot of water from spillway height  to -1.0′ on the gauge was drawn out by three operating siphons in 60 hours.
  • The 3rd foot of water from -1.0′ to -2.0′ on the gauge was drawn out by two operating siphons in 70 hours. (6″ siphon shut down 9/16/19)
  • The 4th foot of water from -2.0′ to -3.0′ on the gauge was drawn out by one operating siphon in 100 hours. (east 12″ siphon shut down 9/20/19)
  • The west 12″ siphon shut down at target depth on 9/22/19.

It was entertaining to watch the last of the siphons shut down at the same time that the lake reached exactly three feet below spillway height.

All’s well here and thanks again for the beautiful construction!
-Scot

September 19, 2019
by rob
Comments Off on Has Lake Truesdale Sprung a Leak?

Has Lake Truesdale Sprung a Leak?

That was the question we got through email from a local resident.

Thankfully there is no leak — just the very quick effects of the planned drawdown project that was successfully re-engineered by volunteers and Pond & Lake Connection after meeting up with several points of failure last season in the initial trial.

Scot Evans reports: “Today at noon (drawdown day #8) a total of three feet [of water] have been pulled out of the lake. We are now 2 feet below the spillway height with one foot to go which will occur on Saturday 9/21 if both siphons continue operating.”

Truesdale spillway with two 12″ siphon pipes and one 6″ siphon pipe. No pumping, just gravity drawing the water down over the spillway and dam. (photo by Scot Evans)

The drawdown will last until February 1, 2020 – that’s when we will turn off the maintenance pipe. This is the smaller 6″ pipe which we will use to try to keep the lake level 2.5 – 3 feet below the spillway level.

After then the lake will fill up with winter snowmelt and spring rain. We anticipate it will be back to regular height by May 1, 2020 and likely well before then.

Check truesdalelake.nextdoor.com for more timely updates and post there if you have questions.

The TEA beach showing the lowered lake level. Currently 2 feet below spillway height and dropping. (photo by Rob Cummings)

September 16, 2019
by rob
Comments Off on Drawdown: Report 1

Drawdown: Report 1

These are some of the email reports and communications from Scot Evans from Truesdale Lake, James Gorman from Pond & Lake Connection, and others involved with the project. Putting selected parts up here for all to see what some of the discussion and learning is looking like.

September 16, 2019

The 6” prototype “helper” siphon shut down today after sucking in air through a whirlpool that developed over its shallow intake tube which is now exposed. No big deal since we are well ahead of schedule during this nice drought we’re having. (See bottom photo.)

View from the west looking east at the spillway with the three siphon pipes installed and water level approximately 1 foot below spillway height.

The siphons have expelled 2.5 feet total and the lake level is now 1.5 feet below the spillway. 

The 12” pipes are still flowing well. The east side pipe has a buckled Fernco fitting near the fill-Tee and the hose clamp has come off of the distal pipe’s lower end as shown in the photo, which I took the day after you energized the siphons. The intense suction has compressed the fitting and the seal is still good. Also, no big deal yet and no need to reposition it or double up on the hose clamps until it shuts down. 

buckled Fernco fitting near the fill-Tee and the hose clamp has come off of the distal pipe’s lower end

When your guys need to climb down, I made steps below the southeast guardrail where it meets the wood beams of the bridge over the siphon intakes. (Where the angled concrete training wall is visible in the second photo above.) I also took a scraper and brush to the spillway’s horizontal deck, so it is clean and not slippery. I marked the painful low hanging bolts under the bridge with ribbon so they don’t prang their heads or shoulders.

So all’s well and no need to do anything yet. I’ll let you know if/when that suction compressed Fernco fitting separates from the tube. 

-Scot


Good news. Thanks for the updates.
I was thinking for the 6” helper…since we should always have water leaving the lake should I add some pipe to that so when the big guys stop water is leaving?

Something to think about. I can do it later in the month but would be nice to do before the water gets real cold.

-James

September 12, 2019
by rob
Comments Off on Lake Drawdown Has Begun for 2019

Lake Drawdown Has Begun for 2019

The Summer boards have been removed from the dam.

Our lake manager Pond & Lake Connection (P&LC) has installed the siphon tubes that will draw the lake level down another 2-3 feet to expose the lake bed over the winter.

[Read about what drawdown is and why this is being done here.]

As detailed in our drawdown meeting in June, our neighbors Scot Evans, resident math whiz Harold Ossher, and our lake manager liaison Lara Gorton have done an unbelievable amount of work to evaluate the water flow and re-design the siphon design to drawdown the water level this fall. See the detailed schematic below. 

Detail of siphon materials and mechanics

For testing, the original 6″ pipe siphon was reinstalled to use for water flow testing and has been in use over the summer. P&LC has installed two new 12″ pipes to have the drawdown complete by Nov 15.

The drawdown will end Feb 1, 2020 and the lake level will be allowed to rise after then. All dates are approximate as all work is weather (rainfall, snow, drought) dependent. 

IMPORTANT: NO FISHING WITHIN 15 FEET OF THE SPILLWAY WHILE THE SIPHONS ARE ACTIVE! The fishing line and hooks get tangled on the pipes and hardware and create a dangerous rusty hazard for lake volunteers and P&LC workers doing observation and maintenance on the site.

The siphons will be drawing water at 1000 cubic feet per minute. There will be warning signs posted at the dam. 

If all goes as planned, the water level will be 2-3 feet lower than the top of the dam spillway and will expose several feet of lakebed.

With cold weather, frost and freezing, the silt in the exposed shallow areas will compact and weed growth will be minimized. 

We will continue to report on the progress as the siphoning proceeds.

Full cross-section of siphon assembly.
Spreadsheet of water flow analysis for drawdown effort. Inputs are highlighted in blue, estimates are highlighted in red, and outputs are highlighted in green.