Lake Manoa,
Part 2: The Big Dig
Thank you for your telephone
calls and notes asking what happened next at Lake Manoa!
Several months ago we ran an
article about the weed and algae problem in the lake, and the successful action
to clean the lake up and reclaim it.
The questions we received from
that article ranged from, "Is there really such a place as Lake
Manoa?" to "How do a group of people in a volunteer organization get
together to drain, re-shape, and refill a lake?"
First:
Yes, Lake Manoa exists!
Lake Manoa is a 14-acre body of water in Lakewood Hills subdivision, just
northwest of Rockford, Illinois, USA.
Second:
Draining, re-shaping, and
re-filling a lake is a fascinating exercise! We hope that the following
descriptions give you a flavor of what the project was like.
The article below was freely
adapted from a report written by Bob Savala, the head of the lake maintenance
committee, Lakewood Hills Association:
Lakewood Hills
Association
1999-2000 Winter
Project: Silt, Sand and Shore
Summary:
This past winter we drained
most of the water out of Lake Manoa, and removed tens of thousands of cubic feet
of silt from the lake bottom. We also built over two hundred feet of sea wall,
reshaped thousands of square feet of beach, and restored over five hundred feet
of shoreline. This was done on a very tight budget using many volunteers.
We demonstrated and learned
many things with this project. For instance, we learned that with teamwork
you can get a lot done with a little money. We also demonstrated that it
is much easier to work machinery and people on a muddy lake bottom when it is
frozen!
Project Objectives:
We set out to do the
following:
-
Improve
the lake depth and lake usability.
-
Reduce
some the obvious algae-breeding areas, deepening them by silt removal.
-
Stabilize
the association shoreline by use of land reclamation and new retaining
walls.
-
Improve
the beach and swim areas by moving and sloping sand out from the beach area
and into the water.
-
Concentrate
on the heavy silt areas: 1) near the creek mouth, and 2) where unprotected
shoreline has eroded over the past several decades.
Bidders on seawall:
The following companies were
originally identified as potential suppliers of steel seawall panels (thanks go
to Dan of Arntzen Corporation for his help in identifying these companies):
-
Diamond
Metal Inc.
-
Northern
Sheet and Coil
-
Superior
Piling Company
-
Rebars
& Steel Company
Thinner steel panels of one
eighth inch, and thicker steel panels of one quarter inch thickness were
originally considered. Research found that for this type of application the
heavier panels were better.
The selected size was one
quarter inch thick interlocking type, eighteen inches wide, six feet tall.
Rebars & Steel Company was selected as the supplier. Their quotation was $34
per panel for 144 panels, totaling $5,315 including tax and delivery charges.
Site Preparation and Digging
After the lake was lowered,
volunteers made an elevation survey of the excavation area using an optical
transit.
Next, volunteers operated a
rented "Bobcat" skid-loader vehicle for several days. They
pushed sand deeper and further into the lake to expand the swimming
area.
Third, they also dug and
smoothed lanes on the lake bottom so that the large machinery would have a
better place to start work.
Heavy Equipment,
Digging, and Trucking
A company called Mark’s Tree
Care subcontracted heavy equipment, trucking, and an extra laborer. They
operated the heavy equipment (a large John Deere backhoe) and performed the
following services in cooperation with Lakewood Hills volunteers:
-
Using
the full power and weight of the heavy equipment, drove the 216 linear feet
of interlocking seawall panels into the ground to a typical depth of four
feet. Most panels penetrated into the limestone beneath the lake. This
created an extremely solid and rigid sea wall!
-
Dug
silt several feet deep, and twenty to thirty feet wide, along the entire
association shoreline west of the beach.
-
Dug
silt several feet deep, and twenty to thirty feet wide, along the entire
association shoreline east of the beach.
-
Repositioned
and rearranged the stone diffuser-filter at the mouth of the creek. (The
rock filter looks like a "dam" to many people, but its real
purpose is to trap silt before it enters the lake.)
-
Re-dug
the deep-traps for silt upstream and downstream of the stone filter.
-
Performed
rough grading on the reclaimed association land.
-
Had
the excess silt trucked away.
The price from several other
bidders to do only a portion of this job had ranged from a low of $19,584 to a
high of $20,400. Mark’s Tree Care charged $12,945 for everything that they
performed and subcontracted.
If you have not seen the
enormous amount of excavation that was done, and the 216 feet of new seawall,
please take a look!
Project Results:
The accomplishments of this
project so far include:
-
A
large amount of association land is reclaimed and improved for recreational
use, ready for finish grading and grass seeding.
-
Over
200 feet of association shoreline is protected by a heavy seawall with a
life expectancy of a quarter century or longer.
-
Decades
of silt accumulation have been removed along the association shoreline and
at the mouth of the creek.
-
Boat
navigation near our association shoreline is now much more practical:
that is, you can operate a boat without running aground!
-
The
silt removal now permits heavy machinery access into the lake for work in
future years.
-
Techniques
have been proven, and a time/cost estimation basis now exists, to continue
silt removal elsewhere in the lake.
Volunteer
Recognition
Thank you, thank you, thank
you to the many volunteers and contributors without whom the 1999-2000 project
would not have been possible! Here is a partial listing:
Tom Lenz:
Donated and delivered 15 truckloads of black topsoil to the association for use
in the finish grading.
Rick Rubert:
Allowed delivery and storage of the seawall panels at his place of business.
Provided his fork lift and unloaded and loaded the panels. Cut a number of
special length panels. Trimmed panels. Helped the driver of the silt truck out
of a slippery area.
Gary Schulz:
Provided his labor and equipment to: remove railroad ties from the lake bottom;
remove a large abandoned drainage tube from the lake bottom; reset equipment at
the beach. Provided a vital clamping tool to safely handle the heavy seawall
panels.
Andy Anastase:
Provided labor during the long hours of setting, driving, and leveling the
panels; provided transportation to obtain laser transit system (loaned by Lynn
Zaugg); operated and maintained the laser transit beacon.
Lynn Zaugg:
Loaned the association his professional laser-beacon transit system; performed
readings, trained crew, provided supervision and follow-up to properly operate
the laser beacon and transit.
Bert LaFleur:
Provided daily monitoring and operation of the dam spill gate control valve to
maintain the lake at the required level (frequent monitoring and adjustment is
required because the lake does NOT hold level automatically when it is lowered).
Provided labor installing panels. Provided and operated optical transit for
original project survey. Operated laser transit. Operated "Bobcat"
skid loader to relocate sand out away from beach and dig and prepare site so the
larger equipment could work efficiently.
Jim Young:
Provided labor and help with panels; traveled to obtain materials; provided
labor when slotting the 200 feet of plastic pipe used to cap the seawall;
provided labor installing the plastic pipe.
Frank Roddy:
Provided labor removing obstructions in the dam spill gate control valve system;
provided labor tree trimming at the dam; provided snow removal whenever needed
for the association parking area.
Eric Peterson:
Provided labor while setting and driving the panels, putting plastic pipe cap
along the seawall, slotting the plastic pipe during preparation.
Bob Babcock:
Provided labor cleaning up and preparing the site for work; provided labor
removing obstructions in the dam spill gate control valve system; provided labor
tree trimming at the dam; provided use of snow plowing vehicle.
Don Ferguson:
Served as second operator for the "Bobcat" skid-loader, moving sand
and doing preparatory digging; provided line-leveling and general labor during
site preparation surveys; provided cell phone as needed; provided project
photography.
Non-association members:
Dom Savala:
Provided labor and assistance during panel lifting, driving and leveling;
provided site coordination, safety supervision, and ground-level feedback to
increase efficiency of machine operations.
Jerry Zaugg:
Provided labor as well as useful training and tips to make the panel
installation safer and more efficient.
Gary Pann:
Provided many hours of labor for the heavy but precision lifting, driving, and
leveling of the seawall panels.
Note: Both Gary Pann and
Eric Peterson are in their early twenties and in good physical condition. Both
of these gentlemen were very much needed for this project! We appreciate so much
the participation of our younger generation!
Status:
Rain with rapid snow melting
began raising the level of the lake in February, 2000. The closing of the
spill gate valve and raising of the lake back to normal height occurred in the second week of March, 2000.
As of the second quarter of 2003, the wall was holding fine!
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