EMERGENCY ACTION PLAN FOR WILLOW LAKE DAM

(Northern Hills Subdivision)

TABLE OF CONTENTS

I. a) Emergency Notification Flow Chart.

   b) Distribution List

II. Statement of Purpose.

III. Project Description.

IV. Emergency Detection, Evaluation and Classification.

V. General Responsibilities.

     A. Dam Owner Responsibilities.

     B. Responsibility for Notification.

     C. Responsibility for Evacuation.

     D. Responsibility for Termination and Follow-Up.

     E. EAP Coordinator Responsibility.

VI. Preparedness.

VII. Inundation Map.

VIII. Appendix

      Plate 1 - Location of Dam in Illinois.

      Plate 2 - Location of Dam in County.

      Plate 3 - Plan & Profile.

      Plate 4 - Embankment & Spillway

      Plate 5 - Emergency Spillway

Parcel Numbers.

Approval of EAP.

I. a) EMERGENY NOTIFICATION FLOW CHART FOR WILLOW LAKE DAM (Northern Hills Subdivision).

I. b) DISTRIBUTION LIST

1. Willow Lake - Board President
2. Secretary
3. Dam Tender
4. Dam Observer.
5. Stephenson County Sheriff’s Department, plus copies for:
6. Chief Deputy
7. Dispatcher
8. 911 Call Center
9. Stephenson County ESDA Office
10. Cedarville Rural Fire Department
11. Harlem Township Garage & Office
12. Gastel & Associates, Engineers
13. Illinois Department of Natural Resources

II. STATEMENT OF PURPOSE

The purpose of this plan is to safeguard lives and reduce damage to property located in the flood plain below Willow Lake Dam in the event of a dam failure.

III. PROJECT DESCRIPTION

Willow Lake Dam is located in the central part of Stephenson County, Illinois on an un-named tributary of the Pecatonica River. The dam and lake are within the Freeport West, Illinois 7.5 minute quadrangle sheet (Section 13, T27N, R27E-latitude 42 deg. 19.9’; longitude 89 deg. 38.3’). Plate 1 shows the general vicinity of the dam, and plate 2 is a location map.

The dam and lake are located in the Northern Hills Subdivision, immediately north of West Fairview Road. The dam impounds a 23 acre lake with a maximum storage capacity of 299 acre-feet. The primary purpose of the lake is recreation.

The dam is an earth fill structure approximately 25ft high and 590ft long at the crest. The primary outlet is a 48in diameter metal drop inlet tube located in the central part of the dam, protected by a trash rack. An 18in diameter corrugated metal tube passes through the dam to discharge water from the bottom of the drop inlet tube. At the base of the drop inlet tube is a valve which may be used for de-watering. The emergency spillway is a concrete chute approximately 110ft long with a 30ft wide lip. Under normal pool conditions, there is approximately 4ft of freeboard. See plates 3, 4 & 5.

The dam is expected to pass a 100 year flood with 1.9ft of freeboard, but would be over topped by the Probable Maximum Flood (PMF).

Although a small dam, because of its location adjacent to homes, water and sewer utility and a road, it is classified as having a high hazard potential, class 1.

IV. EMERGENCY DETECTION, EVALUATION AND CLASSIFICATION

There are two possible types of failure:

Type 1 - Imminent failure. A situation where failure either has occurred or is about to occur. The most likely cause would be high flood conditions.

Type 2 - Potential failure. In this condition failure is developing more slowly and remedial action may be possible to prevent failure. Slow seepage is an example. A type 2 mechanism may rapidly develop into a type 1 failure.

Notes for chart:

1. An inverted filter is a series of layers of material designed to allow the passage of water, but designed to inhibit the movement of earth. Typically this consists of layers; first a cloth blanket, then coarse sand, pea gravel, and 3-5" rock. Height 3 - 5ft.

2. Contact contractor to bring in mixed size rock to plug hole.

3. Practice rodent control as approved by the Illinois Department of Natural Resources Wildlife Biologist.

4. A boil ring dike is a wall of small rocks, sand and gravel designed to permit the outflow of water, but inhibit the movement of sand or earth.

5. The probability of an earthquake occurring in this area of Illinois is remote. Per BOCA-99 the effective peak velocity for this dam is 0.05Ab

6. The most likely failure mechanism for this dam is overtopping as the result of heavy rainfall. Much of the downstream plain is low lying, and it is probable that this area would already be flooded. A dam failure would therefore compound these flood conditions.
See inundation map in section VII. (This map is available off-line.)

V. GENERAL RESPONSIBILITIES

A. Dam Owner
Willow Lake and Dam are owned by the 46 lots surrounding the lake as "Tenants in Common". The lake front lot owners have an association administered by an elected board of directors.

One board member has responsibility for all matters related to the dam and is the Dam Tender. This includes:

• Annual dam inspection and report by a qualified engineer.
• Maintain the Emergency Action Plan.
• Conduct intermediate dam inspections.
• Maintenance & repairs.

B. Responsibility for Notification - Initial Observers
A minimum of two association members will be designated by the Board President as Initial Observers. A primary observer, usually the Dam Tender, and a back-up as identified on the Notification Flow Chart, section II. These observers will use the guide lines outlined in section IV, and have the responsibility to initiate a type 1 emergency response by dialing 911. The following scripted message will be used:

Since these observers are not professionally qualified or employed by the Association, they will seek advice from the Civil Engineer identified on the flow chart for remedial actions in the event of a type 2 emergency.

These observers are responsible for informing the Board President of the situation.

C. Responsibility for Evacuation.

Responsibility for issuing an evacuation advisory is the responsibility of the County Board Chhairman.  The Sheriff’s Department may inform affected residents.

The following residents will be notified:

Name and telephone number correct as of 12 October 2000.

Risks:

• Wave indicates the probability that a sudden failure would generate damage to this property as a result of a wave of water.
• Flood indicates that these properties would receive damage as a result of water seeping into lower levels.

It may be necessary to close West Fairview Road to through traffic for the duration of the emergency.

D. ESDA

The emergency services coordinator will determine what involvement is required from other agencies such as:

• Cedarville Rural Fire Department.
• Harlem Township for road closure and repairs.
• Northern Hills Utility for restoration of water and sewer service, and EPA notification.

E. News Media & National Weather Service

The news media will be informed of the situation at the dam, but will not be used to disseminate emergency warnings. Responsibility for these communications rests with the Board President.

An emergency would be a very localized, though serious event, therefore the National Weather Service will not be used for emergency warning.

VI. PREPAREDNESS

A. Surveillance

i) Normal Conditions

Several visual water level gages have been installed to monitor lake level.

In addition to the annual inspection, the Dam Tender conducts periodic inspections to check for:

• Erosion.
• Seepage
• Cracks
• Settlement

The primary vegetation is grass. The Board establishes a weekly mowing schedule for the growing season. The grass is kept short to discourage rodent burrowing.

Trees which tend to grow in the stream bed are removed.

The trash rack over the drop inlet tube is cleaned regularly after any storm event and painted as needed.

The outlet tube is inspected and the sacrificial tip replaced.

The integrity of the rip-rap on the upstream face is checked and restored as required, as is the rip-rap lining the down stream outlet.

The concrete emergency spillway is checked for cracks and repaired as necessary.

Several springs rise in the stream bed downstream from the emergency spillway. These are monitored regularly.

ii) Unusual Conditions

After any unusual storm event the dam is monitored and inspected by the Dam Tender using the criteria in section 4.

If the National Weather Service issues a notice that heavy rains are expected, the draw down valve must be opened.

If the reservoir rises 2ft above the normal pool level, that is approximately 2ft of freeboard remain, one of the Initial Observers will begin monitoring the dam as noted in section 4.

If it becomes necessary to issue an emergency evacuation order, residents will not be permitted to return until:

• The water level has dropped to within 1ft of normal pool level.
• The dam has been inspected and declared safe.

B. Response During Periods of Darkness

If emergency lighting is required, a truck or car will be driven onto the dam to provide it.

C. Access

Access to the crest and east section of the dam is from Oriole Drive. An easement exits along the south edge of the property at 2086 Oriole Drive. Access to the west bank of the dam and spillway is from West Fairview Road by crossing Northern Hills Utility property.

D. Response During Weekends and Holidays

The Dam Tender / Primary Observer will coordinate their absence from the dam with the Board President. The Board President will, if necessary, delegate observation to an alternate member of the Association.

E. Response During Periods of Adverse Weather

Access to the dam is by foot as noted in item C. Water level gages will be observed from other points around the lake.

F. Communications

Primary communications will be by telephone from 2100 Oriole Drive. A cellular telephone may be used for back-up.

G. Emergency Supplies

Two quarries are located within one mile and are available as a source of emergency fill material.

VII. INNUNDATION MAP

Refer to the inundation map which assumes a worst case "instantaneous" dam failure:
(This map is available off-line).

1. Approximate limits of initial inundation are subject to a dam breach wave at the 790 ft. contour north of West Fairview Road.

2. The water will then back up on the north side of US Rt. 20 (Bypass) at the 770 ft contour, and gradually drain through the culvert under the road into the Pecatonica River. At least 5 ft of freeboard will remain. The bypass will not be over-topped.

PARCEL NUMBERS

Each time this EAP is updated, the residents name and telephone number, listed in the table section V-C, should be re-affirmed. To do this visit the Supervisor of Assessments Office, Stephenson County Courthouse. Use the parcel numbers listed below to verify current residents name.

VIII. APPROVALS

Owners Representative _______________________________ _____________
Willow Lake Assoc.      Martin Oakes                                          Date

Stephenson County _______________________________ _____________
Sheriff’s Dept.              David Snyders                                         Date

Emergency Services ________________________________ ______________
ESDA                          Terry Groves                                           Date

VIII. APPENDIX (Plates available off line)

Plate 1             Illinois Counties
Plate 2             Location Map
Plate 3             Plan & Profile of Dam
Plate 4             Embankment & Primary Spillway
Plate 5             Emergency Spillway

This page revised 24 Oct 2001 posted on web site 11 May 2002.