Hayward Lake Dam 2014 Inspection Report.pdf

INTRODUCTION

The purpose of this inspection was to evaluate this dam’s structural conditions and hydraulic capacity in accordance with Part 315, Dam Safety, of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended, and the Memorandum of Understanding between the Department of Natural Resources (DNR) and the Department of Environmental Quality (DEQ), entitled "Inspection and Maintenance of DNR Owned Dams." The report is limited to a discussion of observations based on a visual investigation and review of any previous inspection reports, plans, and data that are available. This report should not be considered an in-depth engineering investigation.

All references to “right” and “left” in this report are based on the observer facing downstream.

CONCLUSIONS AND RECOMMENDATIONS

The Hayward Lake Dam remains in satisfactory condition. There were no deficiencies observed during the inspection that would lead to the dam’s failure. The dam has adequate spillway capacity under existing conditions.

The following recommendation should be completed as directed.

1. Repair minor erosion of the concrete at the base of the spillway piers as soon as resources allow. A permit from the DEQ will not be required for this activity.

The current low hazard rating is appropriate.

PROJECT INFORMATION

The Hayward Lake Dam was constructed in 1952 to stabilize the level of Hayward Lake and provide a wildlife habitat. Reduced copies of the design plans are on file with the Dam Safety Program.

The Hayward Lake Dam consists of a 161-foot long earth embankment with a height of

9.5 feet, as measured from the top of the embankment to the invert of the outlet channel. The principal spillway consists of a straight drop concrete structure with five bays. The center bay has two 5.25-foot long stoplog sections. The four remaining bays each have a 10-foot long fixed crest concrete section. The total spillway length is 50 feet, 6 inches.

The height of the dam, as defined by Part 315, is the difference in elevation from the design flood elevation to the invert of the outlet stream. That height for the Hayward Lake Dam is approximately 8.5 feet. The head, or difference in upstream and downstream water elevations, was approximately 5 feet on the date of the inspection.

The normal freeboard is approximately 4 feet. The impoundment created by the dam has a surface area of approximately 1,800 acres under normal conditions.

Inspection reports from 1999, 2004, and 2009, prepared by the Dam Safety Program, were used as references for this report.

SITE INVESTIGATION

The following discussion of the dam’s physical condition and appurtenances is based on observations and photographs obtained on the inspection date.

The Hayward Lake Dam is in good condition. The earth embankment is in good condition, as shown in Photographs 2 and 4. No slumps, slides, or areas of settlement or erosion were observed.

The spillway is generally in good condition, as shown in Photographs 1 and 9. The concrete is in fair to good condition. The noses of all the spillway piers are either chipped or have small pieces missing, as shown in Photographs 5 through 9. However, none of these are a cause for concern at this time. All concrete surfaces that have been exposed to running water show some surface erosion. The upstream face of the spillway is shown in Photograph 3. There are some historical cracks that were first observed in 1991 in various locations on the downstream headwalls. None of them show evidence of recent movement and are not cause for concern at this time.

Concrete erosion continues at the base of the spillway piers, as shown in Photographs 10 and 11. The erosion is slightly worse than the previous inspection.

These areas should be repaired before they get worse and threaten the stability of the bridge piers. These repairs should be completed as soon as resources allow and will not require a permit from the DEQ.

STRUCTURAL STABILITY

Based on the conditions observed during the field inspection, the dam appears to be stable. No further structural stability analysis is warranted at this time.

HYDRAULICS AND HYDROLOGY

The contributing drainage area of the Walton River at the dam is 52 square miles. The design discharge for this dam is the 1 percent chance (100-year) flood discharge, which is estimated to be 800 cubic feet per second (cfs). The existing spillway capacity is estimated to be 860 cfs, with 1.0 feet of freeboard. Therefore, the dam is considered to have adequate spillway capacity. Hydraulic calculations are on file with the Dam Safety Program.

OPERATION AND MAINTENANCE

Operation of the dam is the responsibility of the owner or their designee. A written Operation and Maintenance Plan (O&M Plan) is on file with the Dam Safety Program.

EMERGENCY ACTION PLAN

No Emergency Action Plan (EAP) exists for this dam. Since the dam has a low hazard potential rating, an EAP is not required.

APPENDICES

A location map and inspection photographs are provided in the appendices.

HAYWARD LAKE DAM

MENOMINEE COUNTY

DAM ID NO. 217

Photograph 1 – Dam viewed from the right downstream bank.

Photograph 2 – Crest and bridge viewed from the left abutment.

Photograph 3 – Upstream face of the dam.

Photograph 4 – Crest and bridge viewed from the right abutment.

Photograph 5 – Spillway weir and pier viewed from the bridge deck.

Photograph 6 – Spillway weir and pier viewed from the bridge deck.

Photograph 7 – Spillway weir and pier viewed from the bridge deck.

Photograph 8 – Spillway weir and pier viewed from the bridge deck.

Photograph 9 – Spillway weir and pier viewed from the bridge deck.

Photograph 10 – Concrete erosion at the base of the pier.

Photograph 11 – Concrete erosion at the base of the pier.