Sugar Run Dam

Appeal Brief Appeal Letter Appeal Analysis

Appeal Brief

DisasterFEMA-1093-DR
ApplicantHighridge Water Authority
Appeal TypeSecond
PA ID#000-91030
PW ID#95584
Date Signed1999-04-27T04:00:00
Citation: FEMA-1093-DR-PA, Highridge Water Authority, DSR 95584

Cross Reference: Pre-disaster Conditions, Temporary Disaster Effects, No Permanent Damage

Summary: Sugar Run Dam is a ninety-year-old earthen water supply dam that is owned by the Highridge Water Authority (subgrantee). On January 19 and 20, 1996, heavy rains melted a deep snowpack resulting in extensive flooding and the declaration of FEMA-1093-DR-PA. The subgrantee estimated that the reservoir came within one foot of overtopping the dam. At the time of the site inspection, the reservoir had been lowered by 22 feet at the recommendation of the subgrantee's consultant. Observations of increased seepage, discolored seepage, distorted piezometers and a tilted surface casing had led the consultant to conclude that the disaster had reduced the safety factor of the dam against failure. Despite these observations, the FEMA inspector stated that there was no visible damage to the dam. Therefore, DSR 95584 was written for zero dollars to document the condition of the dam at the time of the inspection. The DSR states that the subgrantee had authorized their consultant to perform a geotechnical study of the dam to investigate possible internal structural damages. The first appeal included the report of the geotechnical investigation of the dam, and requested that FEMA fund $5,487,905 for the rehabilitation of Sugar Run Dam. The report contends that the dam was damaged by the disaster, and that it requires an earthfill buttress, a new spillway and improvements to appurtenant facilities. FEMA determined that the report did not substantiate the claim that the disaster damaged the dam, so the first appeal was denied. In the second appeal, the subgrantee pointed out one error in FEMA's first appeal response, highlighted some of the data presented in their geotechnical report, and emphasized that damage caused by the disaster resulted in the necessity of lowering the elevation of the reservoir. However, no new information was presented. Although not specifically stated, it is assumed that the subgrantee is still requesting funding of $5,487,905 for dam rehabilitation.

Issues:
  1. Did the disaster cause increased seepage and embankment distortions?
  2. Are these observed effects indications of facility damage?
  3. Is the proposed dam rehabilitation eligible for FEMA funding?
Findings:
  1. Yes. High reservoir levels caused by the disaster produced these effects.
  2. No. The effects were temporary responses of the dam to high water.
  3. No. The rehabilitation is necessary because of pre-disaster conditions.
Rationale: FEMA funding for permanent restoration of a facility is available only for damages caused by the disaster.

Appeal Letter

April 27, 1999

Charles F. Wynne
Director
Pennsylvania Emergency Management Agency
Post Office Box 3321
Harrisburg, Pennsylvania 17105-3321

RE: Second Appeal - Highridge Water Authority, Sugar Run Dam, FEMA-1093-DR-PA, DSR 95584

Dear Mr. Wynne:

This letter is in response to the referenced second appeal transmitted by your letter dated October 16, 1998. In the appeal, the subgrantee is claiming $5,487,905 for the rehabilitation of Sugar Run Dam.

As discussed in the enclosed analysis, I have determined that high reservoir levels caused by the disaster produced the observed increases in seepage through the dam and its abutments, and the distortions detected in the piezometers. However, these effects were temporary responses of the dam to high water, and do not constitute facility damage. The proposed rehabilitation of the dam is necessary because of pre-disaster conditions, and is therefore not eligible. FEMA funding for permanent restoration of a facility is available only for damages caused by the disaster.

The subgrantee's appeal is denied. Please inform the applicant of my determination. In accordance with the appeal procedure governing appeal decisions made on or after May 8, 1998, my decision constitutes the final decision on this matter. The current appeal procedure was published as a final rule in the Federal Register on April 8, 1998. It amends 44 CFR 206.206.

Sincerely,

/S/

Lacy E. Suiter
Executive Associate Director
Response and Recovery Directorate
Enclosure

cc: Rita A. Calvan
Regional Director
FEMA Region III

Appeal Analysis

BACKGROUND

Sugar Run Dam is a ninety-year-old earthen water supply dam. The dam, with a crest length of 900 feet and a maximum height of 62 feet, is owned and operated by the Highridge Water Authority (subgrantee). The reservoir is normally operated at elevation 1,612.5 feet, the level of the spillway, leaving 4.5 feet of freeboard to the top of the dam at elevation 1,617 feet. On January 19 and 20, 1996, heavy rains melted a deep snowpack resulting in extensive flooding and the declaration of FEMA-1093-DR-PA. The subgrantee estimated that there was 3.5 feet of water going over the spillway during a site inspection on January 20, 1996. This places the reservoir level at one foot below the crest of the dam.

A team of federal, state and local inspectors visited the site on June 26, 1996, to assess the extent of damage to the dam due to the disaster. The reservoir had been lowered to elevation 1,590 feet at the recommendation of the subgrantee's consultant. Observations of increased seepage, discolored seepage, distorted piezometers and a tilted surface casing had led the consultant to conclude that the disaster had reduced the safety factor of the dam against failure. Despite these observations, the Federal Emergency Management Agency (FEMA) inspector stated that there was no visible damage to the dam. Therefore, Damage Survey Report (DSR) 95584 was written for zero dollars to document the condition of the dam at the time of the inspection. The DSR narrative states that the subgrantee had authorized their consultant to perform a geotechnical study of the dam to investigate possible internal structural damages.

First Appeal

On December 12, 1997, the Pennsylvania Emergency Management Agency (PEMA) forwarded a letter from the subgrantee that transmitted the report of the geotechnical investigation of the dam, and requested that FEMA fund $5,487,905 for the rehabilitation of Sugar Run Dam. The report contends that the dam was damaged by the disaster, and that it requires an earthfill buttress, a new spillway and improvements to appurtenant facilities. In a letter dated June 16, 1998, FEMA determined that the report did not substantiate the claim that the disaster damaged the dam. FEMA is prohibited from funding damages that did not result from the disaster, so the first appeal was denied. The subgrantee stated that this report and request for funding were the completion of their application for funding (rather than an appeal). However, FEMA determined that the above-referenced letter was the first appeal of DSR 95584.

Second Appeal

On October 16, 1998, PEMA transmitted the subgrantee's second appeal to FEMA. The subgrantee pointed out an error in FEMA's first appeal response regarding the flood elevation, highlighted some of the data presented in their geotechnical report, and emphasized that damage caused by the disaster resulted in the necessity of lowering the elevation of the reservoir. However, no new information was presented. Although not specifically stated, it is assumed that the subgrantee is still requesting funding of $5,487,905 for dam rehabilitation.

DISCUSSION

The main issue in the second appeal is whether the disaster caused damages that necessitate the proposed rehabilitation of Sugar Run Dam. This issue will be examined by presenting a history of dam inspections, by describing the subgrantee's observations that, in its opinion, indicate disaster-related damages to the dam, and by evaluating these claims of damages.

History of Dam Inspections

The U.S. Army Corps of Engineers (USACE) inspected the dam in 1978. Prior dam inspections made by the State are summarized in the report of this inspection. The USACE recommended an immediate investigation of the dam's stability because of slope irregularities and wet areas on the downstream slope, and the presence of numerous seeps at the toe containing "yellow boy." Yellow boy is water containing dissolved iron and sulfate constituents (ferric hydroxide) derived from coal. In addition, comparison of seepage quantities in 1978 with past seepage quantities indicated that seepage quantities had doubled.

In 1981, Gannett Fleming Corddry Carpenter, Inc. conducted the investigation recommended by USACE. As part of the investigation, three nested observation well and piezometer installations were constructed in boreholes near the maximum section of the dam, near the top (B-1), bottom (B-2) and toe (B-3) of the downstream face. The behavior of these observation wells and piezometers after the disaster is the primary basis of the subgrantee's appeal. Gannett Fleming performed a stability analysis of the embankment based on the observations from the test borings and the results of laboratory tests on soil samples. The analysis yielded a safety factor against sliding of 1.77. This is higher than the required factor of safety of 1.5 recommended by the USACE.

In 1990, Gannet Fleming prepared an annual inspection report of the dam. Selected observations follow. They observed a wet area with "yellow boy" deposits on the left abutment. Weir boxes A and D also contained "yellow boy" deposits. Weir boxes B and C contained 3 to 4 inches of sand. Downstream face moisture was observed for some distance above the toe.

In 1994, GTech, Inc., the subgrantee's current geotechnical consultant, inspected the dam. They observed small sediment deltas at three of the four weirs. Reportedly, the fourth weir had recently been cleaned of sediment. An area of seepage was noted on the right abutment at the same location observed in the 1978 inspection. Seepage from the left abutment was also observed along with the presence of yellow boy. The report presented conceptual designs for the rehabilitation of the dam including an earthfill buttress, a new spillway and improvements to appurtenant facilities. This report is the last pre-disaster inspection report included with the appeal documents.

Post-disaster Observations

In their second appeal, the subgrantee states that the following observations made in April 1996 after the disaster were not present in the 1994 inspection before the disaster:
  • An extension of an existing seepage line on the downstream slope by 137 feet;
  • Seepage from the downstream toe of the dam;
  • Discharge of "yellow boy" from two of the toe drain outlets where such discharge had not been recently observed;
  • Distortion of the riser tubes of certain piezometers; and
  • Downslope movement of the steel casing at boring B-3 that prevented the removal of the observation well cap.

The subgrantee states that these field observations suggested a reduction in the stability of the downstream slope that was caused by the disaster. They assert that without the adverse effects of the disaster, it is highly unlikely that the partial drawdown and loss of the use of the reservoir would have been necessary.

Evaluation of Damage Claims

FEMA Region III enlisted the services of a contractor to review the geological aspects of the first and second appeals. The Executive Associate Director asked a contractor with substantial earthfill dam experience to review the geotechnical engineering aspects of the second appeal

The subgrantee believes that the disaster represents the Flood of Record for Sugar Run Dam. In the presence of record high water levels, it is to be expected that seepage would increase through a dam that has a ninety-year history of embankment seepage. Increased seepage of itself does not constitute damage to the dam. Damage would occur only if extensive piping (internal erosion of the dam) occurred and/or the factor of safety against slope failure were reduced to about 1.2 or lower. ingeotechnical report did not contain a quantitative analysis of dam stability. However, the level of the record flood was only about 8 percent above the normal reservoir level. The second appeal analyst estimated that this increase in water pressure would reduce the calculated factor of safety against slope failure from 1.77 (Gannett Fleming, 1981) to roughly 1.5 to 1.6. This relatively small (and temporary) reduction in factor of safety is consistent with the lack of any signs of impending slope failure such as cracks in the downslope surface, head scarps or toe bulges. The minimum embankment factor of safety recommended by USACE is 1.5 for long-term stability.

Groundwater pressures from the fractured rock on the right abutment do not appear to have a significant effect on the embankment despite contentions to the contrary by the subgrantee's geotechnical consultant. The fractured rock is overlain by about 9 feet of clayey colluvium that creates a confined aquifer in the rock. The piezometer measurements in borings B-1 and B-2 show that the piezometric head in the embankment is 35 feet higher than in the underlying alluvium and fractured rock. This clearly demonstrates that there is very little hydraulic connection between the embankment soils and the fractured rock. Therefore, groundwater pressures in the right abutment do not appear to have affected the stability of the dam.

"Yellow boy" has been observed in wet areas on both abutments since at least 1978. The presence of increased amounts of "yellow boy" is related to the increased amounts of seepage. This is a chemical phenomenon that is not indicative of physical damage to the dam.

The reported distortions of piezometer riser tubes are likely due to minor movements of the embankment in reaction to increased water pressures. The increase in lateral stresses would cause the soils comprising the embankment to deform. These deformations do not, however, constitute a significant decrease in the stability of the dam. They are mostly temporary and are directly related to increased water levels in the reservoir. Typically, most of the deformation would reverse after the lateral stresses were reduced by lowering the reservoir level.

The 1990 Annual Inspection Report of Sugar Run Dam includes the observation that the casing at boring B-3 was tilted downhill indicating possible recent slope movement. The tilt of the casing was observed to be greater after the disaster than it was before the disaster. It appears that the disaster caused additional slope movements. Protective casings such as the one at boring B-3 are normally only 2 to 4 feet deep. A small, deep-seated slope movement would not cause the observed tilting. Such tilting can only be caused by downhill movement of the top 1 to 3 feet of soil. When the excess water in the upper few feet of soil drained away, the slope movements stopped. While this type of slope movement is certainly not desirable, it does not pose a threat to the stability of the dam.

CONCLUSION

The disaster affected Sugar Run Dam in several ways. There were observations of increased seepage, piezometer tube deformations, and a tilted surface casing. Except for the tilted casing, all of the disaster-related effects were temporary. None of the disaster-related effects constitute significant damage to the dam. Lowering the level of the reservoir until the planned dam rehabilitation is completed may have been prudent considering the age and deteriorated condition of the dam. However, FEMA cannot participate in funding this rehabilitation because the need for rehabilitation was not caused by the disaster. Therefore, the appeal is denied.
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