ML20209D707
| ML20209D707 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 10/08/1998 |
| From: | Bryant R FEDERAL ENERGY REGULATORY COMMISSION |
| To: | |
| Shared Package | |
| ML20196J625 | List: |
| References | |
| NUDOCS 9907140001 | |
| Download: ML20209D707 (22) | |
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OPERATION INSPECTION REPORT for THE NUCLEAR REGULATORY COMMISSION Inspection by THE FEDERAL ENERGY REGULATORY COMMISSION Atlanta Regional Office Date of inspection October 8.
1998 Dam (name)
Farley Cateaory I Cooling Water Storage Pond Dam Location Farley Nuclear Station Houston Alabama (Facility)
(County)
(State)
NRC Licensed Project Joseph M.
Farley Nuclear Plant Licensee Alabama Power Company Features of the Dam and Impoundment Inspected rmhankment and associated structures Inspected by Robert L.
Bryant Accompanied by Messrs. Daniel Rom. NRC-Hot Bob Caldwell.
NRC-RI; Tom Johnson. NRC-Farley; Walter Simms. Robert Fucich.
Larry Dunlap. and Andy Patko. SNC Weather overcast. temperature approximately 70 F ( 21*C) summary Based on a review of project design documents, maintenance and instrumentation records, discussions with NRC representatives and SNC employees, and observations made during the inspection, no conditions were found that should adversely affect the immediate safety and permanence of the project structures.
- However, observations made during the field inspection revealed problems relating to undesirable vegetation in the dam's upstream protective riprap (stone) and fire ant colonies in the dam's earthfill.
These conditions could lead to significant safety problems if not corrected.
A complete list of recommendations is included in the f
text of the report.
A project description, pertinent data sheet, project location map and site plan follow. A photograph location map precedes the photographs attached to the report.
Submitte h
Robert L. Bryant, P.E.
9907140001 990702 PDR ADOCK 05000348 P
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. Project Description The Joseph M. Farley Nuclear Plant is located on the west bank of the Chattahoochee River in the southeast corner of Alabama.
The plant is owned by Alabama Power Company, a division of The Southern company, and is licensed by the Nuclear Regulatory Commission.
The Farley Category I Cooling Water Storage Pond is the ultimate heat sink for the plant.
The storage pond was built on the right bank of the Chattahoochee River by constructing a homogeneous earthen dam across a small valley.
Embankment fill material was excavated from within the area of the proposed pond.
During construction, pervious sands were removed from some areas of the dam's foundation and replaced with embankment fill material.
The dam is founded on relatively impervious materials.
The dam was constructed with a chimney drain downstream of its centerline.
The main dan extends in a north-south direction along the east side of the pond.
The dam curves and continues to the west.
The western portion of the dam is also called the west dike.
The water source for the pond is a river intake structure on the Chattahoochee River.
The water is transported by pipeline to a discharge structure on the upstream i
side of the dam.
Effluent from the pond is channeled to a spillway drop structure and then directed to a natural drainage channel for return to the Chattahoochee River.
I The upstream slopes are protected by riprap (stone) in the areas potentially affected by wave action.
The downstream slopes are protected by a well established grass cover.
Pressure relief wells on the downstream side of the dam help control seepage.
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. TABLE 1 Pertinent Data Dam:
Year Constructed.......................................
1976 Type................................... Homogeneous earthfill Length 3900 feet Crest Elevation 195 feet Crest Width 30 feet Slopes:
Main Dam:
Upstream...............................
4 (H) :1(V)
Downstream.............................
3 ( H) : 1) V)
West Dike:
Upstream..............................
3.5(H):1(V)
Downstream...........................
2. 5 (H) : 1) V)
Spillway Type.................................. Uncontrolled Reservoir:
Drainage area Normal pool elevation.............................quare miles 0.5 s i
185.0 feet Surface area 9 el. 184.0 ft.
.................. 95 acres l
Volume:
Below el. 161 feet......................
109 acre-feet Below al. 184 feet.....................
1579 acre-feet Below al. 186 feet.....................
1863 acre-feet Above el. 186 feet......................
811 acre-feet Maximum 2,674 acre-feet 1
Location:
.................... Latitude 31.2225, Longitude 85.1117 NATDAM Numbers AL83101 Hasard Potential:........................................... Low I
NOTE: All elevations are mean sea level.
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SITE PLAN
A.
Safety of the Project.
1.
- Damm, Dikes.
and Appurtenant structures.
The inspection team walked the crest and downstream toe of the dam, the abutments, drain outlet, associated structures, and all accessible l
areas of the spillway.
No conditions were observed that should
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adversely affect the immediate safety and permanence of the project structures.
a.
storage Pond Dam.
The dam was inspected by walking the crest and toe.
Areas of interest were more closely examined on both the upstream and downstream slopes.
The upstream slope (Photographs 1,
3, 4,
and 7) was stabilized with stone (riprap) to protect the earth dam from erosion due to wave action.
The stone appeared to be in good condition, with no indication of weathering.
No abnormalities in the upstream slope such as sliding, sloughing, or subsidence were observed.
A considerable j
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amount of vegetative growth was observed in the riprap (Photographs 1 and 4).
This vegetation should be treated to prohibit growth and removed as necessary.
The crest and roadway along the top of the dam (Photograph 3) appeared to be in good condition, with no indication of cracking, I
f sliding, settlement, or erosion.
Several fire ant mounds were i
observed near the crest.
These should be eradicated.
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The downstream slope appeared to be in good condition (Photographs 2 and 11).
The slope is protected by a well established grass cover.
Some areas along the toe of the slope h
near the north end of the dam (Photograph 11) supported vegetation f
typical of that found in wet areas.
The licensee's biennial inspection on June 10, 1998, was made after a period of dry weather I
and found the area to be wet.
This indicates the presence of seepage through the dam.
The area should be kept under observation during routine inspections.
Any change in the condition of the areas should be noted.
The water intake pipe and concrete wall along the top of the dam (Photograph 7) were straight and well aligned.
Misalignment of these structures can be indicators of shifting or movement in the supporting earth dam.
The water intake pipe is a potential source I
of leaks that could cause erosion of the upstream slope of the earth dam.
Ideally, the pipe should be relocated to eliminate this potential hazard.
Since the pipe is installed along the top of the dam, it should be inspected for leaks on a regular basis (no less than weekly).
The concrete wall protects the intake pipe from 1
I traffic on the crest of the dam and would serve to redirect flow into the reservoir from any pipe leak.
Previous inspections l
expressed concern over loss or deterioration of joint material at l
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construction joints in the wall.
The joints in the wall are inspected and repaired in accordance with routine inspection and j
maintenance procedures.
Drains at the base of the wall allow rainfall runoff from the crest of the dam to pass through the wall r
and into the reservoir.
i b.
Spilivay structure.
The spillway structure (Photographs 12 and 13) is a reinforced concrete, uncontrolled, i
three bay, drop type structure located northwest of the pond under the main entrance road to the Farley Nuclear Plant.
The structure I
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hydrostatic pressure.
The spillway channel connecting the pond to the drop structure is a large excavated ditch with grass lined, l
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The invert to the channel is at elevation 186 feet.
Since normal pool elevation is 185 feet, the spillway is used infrequently and is normally dry.
Water levels in the pond are maintained by controlling the volume of water released into the pond at the intake structure.
The spillway was last used after j
heavy rains in February 1986.
The spillway channel extends past i
l the spillway structure into a natural drainage area.
Any flow from l
the spillway would pass into a creek and subsequently into the chattahoochee River approximately 2 miles from the spillway structure.
No sign of cracking or displacement was observed in the l
concrete spillway structure.
The steel sheet pile walls on either l
side of the spillway structure also appeared to be stable and in good condition.
No misalignment or bulging of the sheet pile walls was observed.
The steel sheet pile walls had a surface layer of corrosion, but did not appear to have significant loss of material due to corrosion.
Inspection of the spillway structure is included I
in the service water storage pond dam biennial inspection. The latest biennial inspection was conducted on June 10, 1998, and found the structure to be in very good condition.
c.
Other structures.
Other structures observed during the course of the inspection included the pond fill discharge (Photographs 5 and 6), the service water intake, the t
l service water return, and the river intake (Photograph 14).
No conditions were observed during the inspection that would indicate the need for remedial action, although some routine maintenance such as painting of the steel walkway and handrails at the pond fill discharge was needed.
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Reservoir.
Portions of the reservoir shoreline were observed from the dam and abutments.
No indications of active shoreline erosion or accumulations of floating trash or debris were observed.
2.
Instrumentation.
Project instrumentation includes 19 surface monuments, 60 observation wells (Photograph 3), and 25 relief wells (Photographs 8 and 9).
Water levels in the pond are monitored electronically and remotely monitored.
Monuments are located along the crest of the dam to monitor horizontal and vertical movement.
Photograph 3 shows typical protective barriers for protection of observation wells and survey reference points.
O'oservation wells are located along the crest of the dam and on selected downstream slope sections.
Relief wells are located in the area downstream of the downstream toe and are connected to a pipe collection system typically 6 to 8 feet (2 to 3 m) below the ground surface.
Instrumentation data for the observation wells and monument surveys was provided in tabular and graphical formats.
Monument surveys are made annually to measure horizontal and vertical movement. observation well and relief well readings are made quarterly.
A review of the instrumentation data revealed no anomalies or unusual trends.
The data indicate that conditions are stable.
Instrumentation and monitoring at this site appear to be adequate for the project size and complexity.
No additional instrumentation appears necessary.
3.
Hazard Potential Classification.
The storage pond l
I dam is classified as having a " Low" hazard potential in accordance with Federal Energy Regulatory Commission criteria.
The storage
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pond dam is located about 4,000 feet (1,200 m) west of the Chattahoochee River.
Natural drainage features in the topography between the dam and the river would convey flow from any dam break directly to the river.
No structures are located along the route of flow from the dam to the river.
The licensee checked building permits in the area and found that no permits have been issued in the past 6 years.
Failure of the storage pond dam would have little impact on water levels in the
- river, certainly not significant enough to upgrade the hazard potential classification.
l 4.
Consultant's Safety Inspection Report.
An indepen-i dent consultant's safety inspection has not been required for this facility.
Based on the small size of the project, the " Low" hazard potential classification, sxcellent condition of the dam, and the existing operation and r.aintenance program, inspection by an independent consultant does not appear to be necessary.
5.
Licensee 8s Inspection Program.
The following table summarizes the licensee's inspection program:
Inspection Frequency By Date Dam Daily FNP Water Level / Temperature Daily FNP Observation / Relief Wells Quarterly APC 07/20/98 U
Horizontal / Vertical Movement Annually APC 04/21/98 Spillway Channel / Structure Biennially FNP 06/11/98 j
Sediment Survey Biennially APC 03/20/98 Dam Biennially APC/SCS 06/10/98 Seepage Test 5-Year FNP 10/19/98 Spillway Channel, Post Storm Pond Level 187+
FNP 02/11/86 j
FNP - Farley Nuclear Plant APC - Alabama Power Company 8C8 - Southern Company services i
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The inspection schedule eppears to be appropriate for detection of potential problems at a project of this size and l
complexity.
B.
Operation and Maintenance.
1.
Dams.
Dikes.
and Appurtenant structures.
The upstream riprap appeared to be in good condition.
The riprap appeared to be stable, provided complete coverage, and showed no deterioration or weathering.
There was a considerable amount of undesirable vegetative growth in the riprap (Photographs 1 and 3) i and near the waterline.
Several fire ant mounds were found along the crest of the dam.
Eradication of these pests should be included in the maintenance program.
The downstream slope has a
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well established grass cover, but was in need of mowing.
Regular mowing inhibits growth of undesirable trees and shrubs and makes detection of any animal burrows easier.
2.
Spillway Gates and standby Power.
The project has no spillway gates.
The spillway is an uncontrolled, reinforced concrete drop structure (Photographs 12 and 13).
The flow passes from the pond, through the spillway channel, the drop spillway structure, the exit spillway channel, into a natural drainage channel, and eventually into the Chattahoochee River.
The invert to the spillway channel is 1 foot above the pond's normal pool elevation and is therefore used only on rare occasions such as an extremely heavy rainfall event that results in higher than normal pond levels.
The last such event occurred in 1986.
I 3.
Power Plants.
There is no hydroelectric power plant i
at this site.
The pond is used to provide emergency cooling water for the nuclear power plant.
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4.
Ramervoir.
Areas of the reservoir observed during this inspection appear to be clean and free of debris.
No indications of erosion were observed.
Operation and maintenance of the reservoir appear to be in accordance with good engineering practice.
Water levels in the pond are maintained by pumping water from the river intake structure on the Chattahoochee River.
Sedimentation in the pond is monitored by the licensee.
5.
Records.
Design / construction /as-built drawings and operation records are maintained by APC at the site.
APC also maintains instrumentation records and other design documents in its Birmingham, Alabama office.
Design / construction records are also maintained at the NRC-HQ offices in Washington, D. c.
6.
Emergency Action Plan.
The storage pond dam is considered a " Low" hazard potential dam.
An emergency action plan does not appear necessary and has not been requested.
The pond provides a separate, emergency 30-day supply of water to the nuclear power plant to permit safe shutdown of the nuclear reactor units in the event of an emergency.
In the event of a dam failure, procedures in the Final Safety Analysis Report (FSAR),
will apply.
Paragraph 9.2.5.2.
of the FSAR states: "
. the need to shut down is indicated by the storage pond level.
An alarm will sound in the control room when the pond is lowered to elevation 184 feet 4 inches.
Under two-unit operation, this will
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allow 90 minutes to evaluate the situation and shut down if required."
High water levels in the pond will also trigger an alarm.
The service water system is reviewed as part of license training every two years.
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C.
Environmental. Public Use, and Safety.
1.
Public Safety Plan.
No public access is allowed on the site, therefore a public safety plan is not required.
2.
Need for Action.
None.
3.
Environmental and Public Use Inspection.
An envi-ronmental and public use inspection is not required, since the public is denied access to the pond.
However, no environmental or safety problems were observed during the inspection.
The Farley Nuclear Plant area is fenced and access road gates are manned by security forces.
Existing personnel safety devices appear adequate and are properly maintained.
No additional actions to protect life and property were recommended as a result of the inspection.
D.
Matters of Commission Interest.
1.
Additions, Betterments, Leases, Retirements, or gagged Extensions.
Not Applicable.
2.
Requiring Commission Action.
Not Applicable.
3.
Project Compliance.
Not Applicable, l
E.
Findings and Followup Actions.
The inspection team observed no conditions that should adversely affect the immediate safety of the project; however, several conditions were observed that could lead to safety problems if left uncorrected.
A meeting was held at the site on the afternoon of October 8, 1998, and the following observations and recommendations were discussed with NRC and APC representatives:
o A considerable amount of undesirable vegetation was found growing in the riprap on the upstream slope l
of the dam.
The vegetation should be eliminated by l
l either physical or chemical means.
Environmentally i
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safe chemical defoliants are available for this l
l purpose.
o Several fire ant mounds were observed along the crest of the dam.
These pests have been known to dig tunnels as deep as 4 feet and lateral foraging burrows as long as 8 feet.
Eradication of these pests should be a part of the regular maintenance and inspection program.
o The flat area at the downstream toe of the dam north of the relief drain system was wet and supported vegetation indicating the continuous presence of water.
This is a probable seepage zone and should be monitored during regular maintenance and inspection.
o The concrete slabs at the exit for the relief drain system appear to have shifted and some have broken edges.
While this condition is not critical to the safety of the project, the conditions should be monitored.
Following the inspection, Mr. Dan Rom, of NRC, was advised that the water supply pipe along the top of the dam is a potential source of leakage that could cause erosion of the earth dam.
If the pipe cannot be relocated, it should be inspected for leaks at ll intervals no greater than one week.
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10/08/98 Upstream slope of the dam as seen from near the right (southwest) abutment.
Note the undesirable vegetation in the riprap (stone) along the slope.
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Note the well established grass cover.
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The barrier around the well is typical of all of the wells.
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Note the vegetation in the riprap.
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c m-Photograph 6 10/08/98 View of the pond fill discharge structure as seen from the walkway on the pond side of the structure.
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Note the undesirable vegetation in the riprap.
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Photograph 8 10/08/98 Manhole for pressure relief well No. 15.
The flag warns mower operators of the location of the
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Effluent from the well flows into a horizontal pipe which connects to an underground collection system.
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y Photograph 11 10/08/98 View of the downstream slope of the dam from near the left (north) abutment.
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l' Photograph 12 10/08/98 Upstream side of the spillway drop structure. Note the steel sheet pile walls.
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