OPERATION AND MAINTENANCE PLAN
Willow Lake Dam, Inventory Number 01205
Prepared for
Willow Lake Association
by Martin Oakes,
Revised January 2001
TABLE OF CONTENTS
1. Telephone numbers.
2. Emergency Procedures.
3. Surveillance.
4. Organization.
5. Operation & Maintenance.
6. Revision History.
1. TELEPHONE NUMBERS
In the event of an emergency, of whatever nature, the persons to contact are:
Bob Thomas, 2266 Oriole drive 815-233-1878 home
Jim Datt, 2161 Eagle Drive 815-232-2747 home
Martin Oakes, 2 1 00 Oriole Drive 815-235-9131 home
Andrew Soria, 2292 Oriole Drive 815-235-4553 home
Jim Teasdale, 2230 Oriole Drive 815-235-4051 home
Larry Frazee, 2160 Oriole Drive 815-235-5366 home
2. EMERGENCY PROCEDURE
In the event of an emergency follow the procedure in the Emergency Action Plan.
3. SURVEILLANCE
Visual inspections of the dam and appurtenances will be made on a routine basis per the schedule noted below. A log will be kept of all inspections and signed by the person making the inspection. See attached record sheet.
Features to be inspected are:
Items to be noted include:
* To improve water flow through the primary outlet, and reduce flow over the secondary spillway the lip of the primary outlet has been notched. This has lowered the normal pool level by approximately 2 in.
The following schedule of inspections will be followed:
I. Normal Conditions of Surveillance.
Normal water elevation is when the water level is lower than the reference lip of the primary spillway to a height 6" above. Under these conditions the dam will be inspected once each month.
II. Unusual Storm Conditions.
During and after unusual storm or flood conditions when the gage height is from 6" to 24" the dam will be inspected once in 24 hours.
If the gage level exceeds 24", procedures will be followed as defined in the Emergency Action Plan.
4. ORGANIZATION
There are 47 ( forty seven) lots surrounding Willow Lake, 46 are occupied by family dwellings, 1 (one) is owned by the Association as an access and service way.
The "Willow Lake Association" has a Board of Directors, elected annually, consisting of :
The object of Willow Lake Association is to secure cooperative action of lake front lot owners of Willow Lake for the purpose of developing and maintaining a high quality, private lake for the mutual benefit of the lake front lot owner, and to contribute to the improvement of Willow Lake.
In addition to the above elected members, the board may appoint other individuals to perform specific technical non-elective functions such as Dam Tender responsible for safety & maintenance.
5. OPERATION AND MAINTENANCE
General
Willow lake is formed by an earthen embankment running approximately east/west and is served by two spillways.
The primary spillway is a 48 in diameter uncontrolled drop inlet tube protected by a metal grill, which discharges through a corrugated metal conduit pipe into a plunge pool south of the darn. At the base of the drop inlet tube is a gate valve equipped with handle such that the valve may be opened from the top of the grill. This valve is connected to a drain tube which projects into the lake bed. Opening this valve is the primary method to draw down the lake. A pipe wrench is required. The emergency spillway is a concrete overflow and chute located approximately 50 ft west of the primary spillway, close to the west end of the dam.
Description of Normal Conditions
The normal pool level is determined by a notch cut in the concrete lip of the primary spillway (drop inlet tube), and is at elevation 796.04.
The reservoir is fed by springs and at the north end, a small stream. Under normal conditions the surface of the lake rises and falls in response to local rainfall and evaporation.
Down stream of the dam is a sewage disposal plant which discharges treated waste water into the same stream bed shared by the dam outlet flow.
Operation
Operation is defined as the administration, management and performance of non-maintenance actions needed to keep the darn performing as planned.
Mechanical equipment is limited to the 12 inch gate valve in the primary spillway. At least annually, or at anytime it is suspected that the draw down conduit is clogged with debris, the gate valve will be fully opened, closed, and returned to the appropriate part open position, to allow some discharge down stream.
This gate valve has been disassembled once and re-packed during the 19 years of operation. This procedure will continue as needed.
The grill covering the drop inlet tube will be cleared of any accumulated debris spring and fall, and after any unusual rainfall.
The cement rim retaining the metal casing of the drop inlet tube will be used as the zero reference for measuring changes in the surface of the impounded water.
The edge of the concrete spillway is surrounded by a fine mesh fish net to prevent the loss of desirable species. This will be cleared of any accumulated debris spring and fall, and after any unusual rainfall.
The site of the reservoir is over what was once marshland, fed by many springs.
During the months when the dam is accessible, that is not covered with ice or snow, and following severe rainfall events, it will inspected for changes in the appearance of the upstream and down stream slopes using the criteria defined for annual dam inspection.
The dam and impoundment are the sole property of the 47 lots surrounding Willow Lake. Access is permitted to the dam slopes for the sole purpose of maintenance. Unauthorized use of the structure and approaches is not permitted. Signs are posted to state that trespassing is not permitted.
Maintenance
Maintenance is the work required to keep the dam in good repair, restore it to its original physical condition, or prevent deterioration.
The dam slopes will be mowed weekly during the months when grass is growing. To ensure this work is performed, a director will publish a schedule of mowing teams for the year. These teams are comprised of the lake lot owners. Each lot owner on a team is responsible for providing labor to complete their share of the mowing. Because all surfaces of the dam are mowed, woody growth is prevented.
At least once each month, tall grass or weeds will be removed from the rip- rap by cutting.
Small rodents (mice) tend to burrow in the dam face. Appropriate humane methods will be used to exterminate them. Holes will be filled and re-seeded.
Large rodents (Muskrats) have not been a problem on the dam, however regular inspection will note any activity.
The dam will be inspected for any areas of grass which need over-seeding, and appropriate seed applied.
At least once each year, during a dry period when there is no flow over the lip of the emergency spillway, any accumulated debris or vegetative material will be removed from the secondary spillway and chute.
No one is permitted to dump garden waste into the down stream waterway.
Vegetative material will be removed from the bank above the south east comer of the wing to permit easy access to the base of the spillway.
The banks of the outlet stream are relatively steep. Small trees and bushes tend to seed and begin growing in the stream bed. At least once each year the base of the stream bed will be cleared of any woody growth, along with the banks for a distance of 50 ft to ensure the capacity of the outlet channel is maintained. In particular fallen trees or limbs will be removed.
The downstream banks of the outlet stream are composed of clay, limestone and small rocks. There is no sign of significant erosion, however it may be anticipated that in the event of a significant flood, scouring and slumping would occur. The capacity of the outlet channel will be restored and maintained to the "As built specification."
Rip-wrap placed along the north face of the dam will be maintained in good condition. Areas which erode will be replaced.
Approximately every seven years the grill will be re-painted to remove any rust accumulation.
At least annually and after any severe rainfall, the rip-rap protecting the plunge pool serving the primary spillway will be inspected and restored as needed. To make access simple, woody growth will be removed from the perimeter of the plunge pool. The banks of the plunge pool will be seeded with appropriate vegetative material to provide stability.
The corrugated conduit providing drainage from the primary spillway will corrode. The exit section is now provided with approximately 3 ft of conduit attached by removable collars. This section will be inspected annually and replaced as required.
The 48 inch drop inlet tube has water flowing down it much of the time. This will be inspected for changes in water seepage, and recaulked as required.
The concrete surface of the emergency spillway, chute and stilling basin will be observed for excessive spalling, cleaned and cracks filled as required.
This plan will be reviewed annually and updated for approval by the Board of Directors of Willow Lake.
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This page prepared 19 April 2001