ML20116L087
| ML20116L087 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 04/30/1985 |
| From: | Bailey J GEORGIA POWER CO. |
| To: | Adensam E Office of Nuclear Reactor Regulation |
| References | |
| GN-593, NUDOCS 8505030476 | |
| Download: ML20116L087 (33) | |
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Georci: Power Company Rout:: 2. Box 299A
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W yn:sboro, Georgis 30830 Telephone 404 554 9961 404 724 8114 Southern Coinpany Services. Inc.
Post Office Box 2625 Birmingham, Alabama 35202 Telephone 205 870~6011 Vogtle Project l
April 30, 1985 i
Director of Nuclear Reactor Regulation Files X3BC35 Attention: Ms. Elinor G. Adensam, Chief Log GN-593 Licensing Branch f4 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 20555 REF: GN-545 Bailey to Denton, Dated 3/12/85, DSER Open Item 112, Groundwater i
NRC DOCKET NUMBERS 50-424 AND 50-425 CONSTRUCTION PERMIT NUMBERS CPPR-108 AND CPPR-109 i V0GTLE ELECTRIC GENERATING PLANT - UNITS 1 AND 2 REQUEST FOR SUPPIEMENTAL INFORMATION DSER OPEN ITEM 112 - GROUNDWATER Dear Mr. Denton l
Your staff has made requests for additional information and clarifications
! related to the ground water data submitted by enclosure to the referenced
! Ictter as the Ground Water Suplement. Some of the staff's requests have required revisions to the Supplement. The sources of these requests include:
- 1) Telephone conference, March 29, 1985,
- 2) Letter f rom E. Adensam to D. Foster, April 11, 1985, and
- 3) Telephone conference, April 17, 1985.
Attached for your staff's review are three sets of staff-requested information and three sets of revisions to the Ground Water Supplement.
If your staff requires any additional information, please do not hesitate to contact me.
ncerely, J. A. Bailey Project Licensing Manager j JAB /msp , ;
Enclosure OU s xc List Attached {g /L b ' s$
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I I a Director of Nuclear Reactor Regulation Files X35C35 l April 30, 1985 Log: GN-593 Page 2 xc D. O. Foster l R. A. Thomas l J. E. Joiner, Esq.
B. W. Churchill, Esq.
M. A. Miller B. Jones, Esq. (w/o enc.)
L. T. Cucwa G. Bockhold, Jr.
T. Johnson (w/o Enc.)
D. C. Teper (w/o Enc.)
L. Fowler Project File l 0254A l
- 1. Boecifications for drillina observation wells 42A. B. C. and D (Telecon April 17)
These wells were drilled and constructed by Law Engineering Testing Co.
under contract to Georgia Power Co. during 1971. Contracts are not kept for more than five years, therefore the specification for drilling and constructing wells 42A, 428, 42C, and 42D are not available. Copies of Law Engineering Testing Co. Test Boring Field Reports (drillers logs) are available and have been reviewed. These reports, dated May 19-27 and July 22-28, 1971, document the drilling and installation procedures used in constructing wells 42A thru 42D.
The following procedure was used:
- Drill to top of design monitoring interval with 3 7/8-inch or larger tricone bit
- Install and seal 2-inch diameter PVC casing in boring by pumping cement grout down through PVC pipe and up into annulus
- Drill out grout in 2-inch PVC casing and advance boring 10 feet into native material (design monitoring interval)
- Install 1-inch diameter PVC screen and pipe for observation well.
- 2. Information and/or specifications on drillina procedures relevant to influence of drillina fluid on vermeability test holes and observation wells (Letter Asril 11)
All permeability test holes and most observation wells (except for the LT, BT and 800 series) were drilled more than five years ago. As stated j above, the drilling contractor specifications for those wells have been destroyed. The technical specifications for drilling and installation of
- the observation wells (piesometers) installed since 1976 are included as I
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Attachment A. Geologic logs, drillers logs, and daily field reports of the test holes and older observation wells have been reviewed. These data show that the holes were d.~illed as follows:
Permeability Test Holes
- 1) No data on drilling fluid used at hole 107A.
- 2) Hole 157 was drilled with bentonite. After drilling, hole was flushed with clean water before permeability testing.
- 3) Hole 170 was drilled with bentonite to top of mari and cased.
After casing, the hole was flushed and then cored using Revert.
The Revert was broken down with fast-break before testing.
- 4) Hole 180 was drilled with bentonite. After drilling, the bentonite was displaced with Revert. The Revert was broken down with fast-break before testing.
- 5) Holes 183 and 184 were drilled with bentonite to depth to be tested. PVC pipe and screen were installed and the holes flushed with clean water.
- 6) The "P" series holes were drilled with clean water obtained from the concrete batch plant.
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The remaining holes were drilled with bentonite to the top of thn Blue Bluff earl Where casing was set. The holes were then flushed out and cored with clear water. Permeabili.ty
.._ , s tests were conducted after drilling was complete. -
Observation wolle drilled 1971-1972 4
Holes completed as observation wells in the confined aquifer were drilled by the following method:
Delli to top of interval to be monitored with bentonite. Install and grout 2-inch PVC casing. After grout has set-up, drill out grout (using clear water) and approximately 10 feet into monitoring zone. Install 1-inch PVC screen and riser pipe. Install gravel pack and seal.
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Holes completed se observation wells in the water table aquifer were drilled as follows:
- 1) Hole drilled to top of earl with bentonite and 2-inch diameter PVC screen and casing installed. Hole flushed with clean water as gravel pack was being installed.
- 2) Hole drilled through earl (originally drilled as exploratory hole).
Molefilledwithcementgrouttogopofearl. PVC screen and casing, 2-inch diasater, installed. Hole flushed with clean water as gravel pack was being installed.
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Rail-testing observation wells observation wells were monitored by Law Engineering Testing Co. from date of installation (1971-1972) thru April 1973, using the following procedure.
- 1) measure water level
- 2) bail well at least 5 times or until dry
- 3) measure water level recovery Balling the wells not only provide a measure of assurance that they respond properly but also serve to develop the wells by removing any drilling fluid that might be present.
Dewatering Test Wells (W-1 and W-2)
These test wells and the eight observation wells were drilled with bentonite. The test wells were cleaned of drilling fluid when developed by pumping. We believe the observation wells were flushed with clean water following installation of casing, although there is no record.
Some bentonite could have remained on the wall of the hole following flushing. However, we do not believe that this partial plugging of the formation (if it occurred) had any detrimental effect on the test results, for the following reasons.
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- 1) As discussed in the Ground Water Supplement, the pumping test at well W-1 was run for 97 hours0.00112 days <br />0.0269 hours <br />1.603836e-4 weeks <br />3.69085e-5 months <br />. The data obtained from this test are considered valid because the test was sufficiently long and the rate of water level drawdown in the observation wells during most of the l
test was slow enough to be unsffected by residual bentonite in the observation wells. Formation invasion of bentonite does not extend great distances from the bore hole, and the test data represent the permeability of the materials between the test well and the observation well, not just materials adjacent to the bore hole.
- 2) These tests were to obtain data for design of a dewatering system for the powerblock excavation. Although W-1 suggests high permeability, the tests at W-2 indicate markedly variable, low, permeability.
Based on these data, it was concluded that inflow of ground water would be small; the Utley limestone would not be a major source of inflow, and the excavation could be dewatered with ditches and sumps. Act.ual experience of the excavation demonstrates this to be a correct analysis. The excavation was dewatered and maintained for four years by use of ditches and sumps. Water level data from observation wells outside the excavation show that the effects of dowatering did not extend large distances. This indicates, from the excavation, that although in limited areas permeability of the Utley l limestone is high (solution cavities), the effective, or average l
l permeability is low. The cavities are poorly connected and the 1
limestone does not act as a high permeable drain, k
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- 3. Omission of initial water level measurements on data sheet of Well 42A in Ground Water Supplement (Telecon April 17)
The omission of the first seven water level measurements made in well 42A on the data sheet in the Ground Water Supplement was an error. It was intended not to include them on the hydrograph as they are not representative of aquifer water levels, but are influenced by water used in construction and development. The data sheet and the hydrograph have been revised and copies are enclosed.
- 4. The staff requested the Geologic lot of well 176 (Telecon March 29)
The hole was drilled to a depth of 80 feet (top of marl) and constructed as an observation well to monitor the water table aquifer. Because the hole was not intended as an exploratory hole there was no geologic los prepared.
- 5. Reported water levels in drill hole 157 (Telecon April 17)
Quarterly water levels were erroneously measured and reported for drill hole 157 from July 1979 until March 1981. A review of records revealed these levels were taken in the 4-inch surface casing of hole 508, which had been sealed with grout to within 30 feet of ground surface following completion of drilling in 1973. It had apparently been assumed that because of the 4-inch steel casing, it was an observation well, and water levels were measured. To compound the error, it was mistakenly identified as 157, located 15 feet from 508, similarly grouted but without surface casing. The water level data sheet for hole 157 should be removed from the Supplement. Figure 2-1 of the Supplement has been revised to remove 157.
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- 6. Drill hole location man (letter. April 11)
A map showing locations of holes 181, 236, 237, 334, 28, 30, 34, 35A, 36A, 36B, 120, 123, 401, 402, 403, 404, 405, 406, 407, OD-1 and RH-1 was requested.
The requested map is enclosed with the following modifications. Because the list of holes is essentially those holes that penetrate the mari and have no closure record, hole 239 is also shown on the map. Mole 334 is not shown on map because there is a closure record for this hole.
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- ATTACHMENT A DRILLING SPECIFICATIONS r - -. .. . .._. __
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. C2.18, Rev. 9
'( C2.18.13 CONSTRUCTION OF PIEZOMETERS A. GENERAL
- 1. Piezometers abandoned due to construction activities may require replacement in order to continue the monitoring program. Results of the monitoring program may determine the need for additional piezometers. Locations and depths of additional piezometers, as required, shall be determined by Engineering. Surveying shall be provided by the owner.
Reference Sketches SE-2-C-289 and SE-2-C-291.
B. DRILLING THE HOLE
. 1. The Contractor may use any method of drilling which, in the opinion of the Owner or his representative, will provide a suitable hole. The drilling machine or machines shall be in good working condition and capable of providing a vertically plumb hole of the required diameter at the maximum drilling depth. Equipment and accessories for drilling, such as casing, drill rods, drill bits, pipe, pumps, meters, gages, tools, power, and other materials or supplies which are, in the opinion of the Owner or his representative, necessary for the work shall be furnished by the Contractor.
- 2. No piezometee hole shall be abandoned before reaching the specified depth without the prior written approval of the Owner of his representative. Piezometer holes abandoned before reaching the specified depth because of mechanical failure of drilling equipment, negligence on the part of the Contractor or other such preventable causes, and rejected by the Owner or his representative, will not be paid for. Any holes rejected shall be supplemented by another hole adjacent to the first. In the event the supplementary hole is lost, it in turn shall be supplemented by another. Regardless of the reason for abandoning a hole, no payment will be made for a move and setup in order to drill a new hole from the same location. The Contractor shall abandon holes in accordance with Paragraph C2.18.16.
. 3. For piezometers extending beneath the earl, drilling shall be performed in two stages. The first stage will be for the purpose of installing a permanent casing in the earl confining layer and shall be terminated 10 feet below the top of the earl, or as directed by the Owner. After the casing has been set and cemented in place, the Contractor shall proceed with the second and final stage of drilling which will extend to the design depth of the piezometer. For piezometers which terminate above the earl a one stage drilling operation using a temporsey casing shall be implemented.
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, . C2.18, Rev. 9
- 4. Water used for drilling shall be clean and free of l
( contaminants. (Clean water from site supply is available.) l Contractor shall furnish a water truck, portable tanks, or other equipment necessary to transport water from its source to the rig. Where a drilling fluid viscosifier is required, a biodegradable product, such as Johnson's " Revert" or Barold's l "E-Z Nud" shall be used. Manufacturer's instructions shall be followed in the mixing and breakdown of the additive. i i
C. PERMANENT CASING (For Use with Piezometers Extending Beneath the j Marl) )
- 1. Unless otherwise directed by the Owner or his representative a permanent casing shall be set and cemented in place to a l minimum depth of 10 feet into the mael confining layer. The cementing of the casing shall be in accordance with the following steps:
- a. Centering guides shall be attached to the outside of the casing to insure uniformity of annular space between the casing and hole wall. Spacing between each set of I centering guides shall be approximately 20 feet for the entire length of the casing. Design and attachment of the guides will be subject to approval by the Owner.
- b. The casing shall be cemented in place using a neat cement grout consisting of one part water to one part cement by
(- volume e.g., one 94-pound sack of cement to 7-1/2 gallons of water.
- c. The annular space shall be filled by inserting a treale pipe into the annulus to a depth of one to two feet off the bottom of the hole and pumping the cement grout under pressure until grout is returned at the surface. To compensate for settling and shrinkage, the Contractor shall add additional grout as needed to maintain the grout column at ground level. Alternative methods of grout sealing shall be subject to approval by the Owner.
- d. The cement grout shall be allowed to cure for a minimum of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> before proceeding with further drilling.
- 2. The permanent casing shall be 6 inch minimum diameter Schedule 40 PVC or steel pipe, shall be approved by the Owner or his representative and shall: (1) receive the piezometer ,
riser pipe and screen assembly without binding or distortion l and (2) allow sufficient clearance for a tremie pipe between l the casing and piezometer riser for placing sand pack, and j cement grout seals within this annular space.
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C2.18, Rev. 9
'( D. TEMPORARY CASING (For Use with Piezometers Terminating above the Marl)
- 1. Unless otherwise directed by the Owner or his representative temporary casing shal*'. be installed to prevent caving of the hole wall during drilling and subsequent operations. i
- 2. Temporary casing used to prevent caving of the hole wall during placement of the well screen and sand envelope shall be removed before completing the well.
- 3. Temporary casing above the sand envelope may be removed or left in place at the option of the Contractor, unless specifically directed by the Owner or his representative.
- 4. Temporary casing shall be ainlaua 6 inch diameter Schedule 40 P7C or steel pipe, shall be approved by the Owner or his representative and shall: (1) receive the permanent casing a"td screen assembly without binding or distortion; (2) provide an annular space opposite the well screens with a minimum thickness of 2 inches for a sand unwelope; and (3) allow sufficient clearance for a trenic pipe between the casing and piezometer riser for placing sand filter packs, bentonite and
. cement grout seals within this annular space.
E. SCREENS
- 1. Between 10 and 20 feet of 2 inch minimum diameter screen shall l9 be required for each piezometer. The length and location of well screen shall be determined by the Owner or his representative. The shapes or opening or slots shall be designed to prevent clogging and shall be free from jagged edges and irregularities that will accelerate clogging or corrosion. The screen shall have adequate strength to resist i the external forces that will be applied after it is installed and to minimize the likelihood of damage during the installation. The size of the screen openings shall be 0.04 inch unless otherwise approved by the Owner oc his representat.ive. The screen shall be joined to the PVC riser pipe with appropriate watertight couplings and shall have true alignment at its joints after installation. Screen shall be stainless steel or PVC, as approved by the Owner or his representative.
- 2. Setting the piezometer riser pipe and screen assembly
- a. The piezometer shall be equipped with a sump, which shall be made by coupling a minimum 5-foot section of blank 2 inch minlaus diameter pipe to the bottom of the l9 screen. The bottom of the sump shall be sealed with an appropriate cap or plug to prevent in-filling while the piezometer assembly is being lowered into the hole.
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C2.18 Rev. 9
- b. Centering devices shall be installed in the piezometer to
- ( aid in the placement of sand in the annular space succounding the screen. Design and placement of the centering devices shall be subject to approval by the Owner.
- c. The Contractor shall exercise all care required to insure that the screen is not damaged during the lowering of the piezometer riser pipe and screen assembly. The assembly shall be lowered to design depth by a sand line, or other Owner approved method, and suspended off the bottom of the hole a distance of 3-6 inches while the sand pack is i being placed in the annular space. This step shall be i performed so that the weight of the piezometer riser does j not place undue pressure on the screen. !
- d. Piezometer riser pipe shall be minimum 2-inch diameter Schedule 40 PVC unless otherwise approved by the Owner or l9 his representative, and shall protrude a minimum of 1 foot and maximum of 2 feet above ground surface.
F. INSTALLATION OF SAND ENVELOPE
- 1. After the assembled riser pipe and screen have been placed in proper position and aligned within the drilled hole and with the bottom end sealed, the sand envelope shall be placed. The k
sand filter pack shall be placed by tremie pipe, or other methods approved by the Owner, in the annular space between the casing-screen and the wall of the hole and shall extend from the bottom of the hole to an elevation above the screen determined by the Owner. The Contractoe shall pump clean water down the riser pipe with returns from the annulus to remove excess drilling fluid prior to placement of the sand filter pack. Circulation shall be controlled such that the hole does not cave-in before or during placement of filter
, pack and grout seal. Care shall be taken to insure that the entire annular space between the screen and the wall of the hole shall be completely filled with sand. l9
- 2. The sand envelope shall consist of clean, well graded sand, maximum size 1/8 inch, with less than 5 percent passing the No. 100 sieve.
G. CLEANING
, 1. Immediately after the riser pipe-screen assembly has been installed, and the sand envelope placed in the annular space, the piezometer shall be cleaned of residual drilling fluids.
Cleaning of the well shall be in accordance with the following steps:
- a. Only clean water from the site water cupply shall be used. The Owner will provide the Contractor with a water 9 source.
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. C2.18. Rev. 9
- b. After the water source hcs been established, clean water
( shall be pumped through the riser until a flow is returned through the annulus to ground surface. A steady flow shall be maintained until all drilling mud, fine-grained materials, and visible discoloration have been eliminated. A small amount of chlorine may be added to the water to assist in the breakdown of the biodegradable drilling aud. This shall be done only as necessary and shall be at the direction of the Owner or his representative.
- c. Diversion, impoundment, and disposal of discharge water shall be as directed by the Owner.
H. BACKFILLING
- 1. An impermeable seal a minimum of 2 feet in thickness shall be l9 provided in the annular space immediately above the filter pack. The seal shall consist of a highly viscous six of bentonite and water, barite and water or a combination of the two. Bentonite pellets may also be used,
- 2. The annular space above the bentonite seal shall be filled with a neat cement grout six of one part cement to one part water by volume. Grout shall be pumped through a tremie pipe which shall be placed to a level 1-2 feet above the bcstonite seal before pumping begins. Pumping shall continue until
( grout is returned to ground level. The Contractor shall add additional grout as required to maintain grout column at l9 secund level.
I. SURFACE SEAL AND PROTECTION
- 1. A protective steel pipe enclosing the piezometer riser shall be provided. The protective pipe shall extend at least 3 feet below the ground surface and shall be set in concrete or
! grouted. When steel is used as the permanent casing, the l protective casing may be provided by extending the permanent l casing. This extender casing shall be attached by welding or threaded coupling. The protective casing shall extend a minimum of 1-inch and a maximum of 6-inches above the top of the PVC riser, and shall be provided with a cap, pin, and lock.
- 2. Four permanent guard posts shall be provided. Reference SK-2-C-108.
J. CONCRETE
- 1. Concrete shall be in accordance with Divisien C3 of this specification. Grout shall be in accordance with Division C3 of this specifi' cation and shall ba placed in accordance with Section 1.5 of AWWA A100-66 Standard for Deep Wells.
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- C2.18, Rev. 9 f C2.18.14 PIE 20 METERS PLACED IN CATEGORY 1 BACKFILL A. GENERAL
- 1. Piezometers shall bs located in Category 1 backfill as required by Engineering. l9 B. CONSTRUCTION OF PIEZONETERS IN CATEGORY 1 BACKFILL
- 1. Piezometers shall be constructed in Category 1 backfill in accordance with Paragraph C2.18.13 of this specification and the following:
- a. Driller may use any conventional drilling technique except jetting.
- b. Drive casing, if used, shall be steel, flush-joint l9 (preferred) or steel threaded collars.
- c. Screens shall be 10 feet long with openings of .040 inch or less. Bottom of screen shall be placed fema 2.0 feet (maximum) above the top of the mael, with the drilled hole extending to the top of the mael. The piezometer 9 shall be equipped with a sump, 2.0 feet in length, coupled to the bottom of the screen.
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- d. Risar pipe shall be schedule 40 PVC.
- e. Piezometers placed in Category 1 backfill and selected for permanent use shall be protected in accordance with Paragraph C2.18.13,I when final grade has been reached.
Interim protection for all piezometers placed in Cat-egory 1 backfill shall be provided by a removable pro- .
tective barrier. Each barrier shall be large enough to l be plainly visible from vehicles and heavy equipment and shall be of a configuration approved by the Owner. The barrier shall be of sufficient strength to resist deformation and to protect the piezometers from inad-vertent damage during the construction period. Anchoeing devices may be used to resist lateral displacement but in no case shall anchoring devices penetrate further than 6 inches into existing backfill material. The barrier shall be painted white unless otherwise approved by the Owner,
- f. Reference attached Sketch SK-2-C-113, Piezometer for Cat. 1 backfill.
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C2.18, Rev. 9
( C2.18.15 DEVELOPING AND TESTING NEW PIE 20 METER INSTALLATIONS A. DEVELOPMENT
- 1. Upon completion of piezometer installations (except shoet term piezometers), the screen shall be developed to remove residual fines and produce maximum efficiency of the piezometer.
Development shall be performed in accordance with the following steps.
- a. Allow the grout seal to cure foe a minimum of 24 houes.
- b. Attach a horizontal jetting device to the end of the lead l9 drill rod and insert rods into piezameter to the top of the screened section.
- c. Using a clean water source tuen on mud pump and slowly move drill string down into the screen and back up again with the rig draw works while rotating rotary table at its slowest speed. All water returned to the sueface shall be diverted to waste (i.e. return watee shall not be recirculated). The objective of this step is to
, repeatedly move the jetting device through the total length of the screen until all fine-grained mateelal 9 surrounding the screen is loosened and allowed to flow into the piezometer. The jetting operation shall be
- continued for a minimum of one hour. The Owner may specify longer periods if fine-grained particles are still visible after the minimum period. Upon completion of this step, residual sediments shall be removed by placing an aie line to the bottom of the piezometee and air lifting until return water is clear and free of fine-grained materials.
- d. In the event that the total length of the screen is greater than the total travel length of the rig draw wocks, then the screen shall be jetted in increments equalling the length of the cig draw wocks. When incremental jetting is necessary, the jetting shall begin in the upper section first and progress downward until all screen sections have been developed a minimum of one
. hour each.
B. TESTING
- 1. After development operations are complete, the piezometer shall be tested to insure that it is performing .
satisfactorily. The following procedure shall be used.
- a. Aftee airlifting the piezometer, allow watee level to stabilize to a static level by allowing the piezometee to sit overnight or as determined by the Owner's rep-g resentative.
- b. Fill the risee pipe to the top with clean water.
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- C2.18, Rev. 9 f c. From a conta;ner of known volume, pour enough clean water l I
into the risor pipe to maintain the water level at the top of the ri.ser.
- d. Record the time required to empty the known-volume container. l
- 2. If the piezometer accepts water from the container at a i constant rate, the piezometer will be considered to be I operative. The t'ine-volume relationships will be formally '
documented and retained by the Owner until the plant is licensed. If the piezometer does not accept water at a constant rate, or if acceptance is noticeably slow, as determined by the Owner or his representative, the airlift cleaning procedure shall be repeated until the piezometer is considered operative.
C2.18.16 ABANDONMENT OF PIEZ0 METERS
- 1. Piezometers which must be abandoned because they interfere with construction activity, are located beneath structures or have been lereparably damaged shall be abandoned, subsequent to approval by Engineering, in accordance with the following:
- a. The depth of the piezometer shall be measured by sounding and compared with available records.
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- b. Loose material in the piezometer shall be removed by washing the piezometer with fresh water pumped through a
- small-diameter pipe or hose inserted into the 2-inch riser or j by use of compressed air. Piezometers located below the earl
! shall be cleaned at least to the bottom of the earl; piezometers located above the earl shall be cleaned at least to the bottom of the screened interval.
- c. All pipe and casing shall be removed from the hole with the exception of drill casing or surface casing already cemented l In place.
- d. Pipe which cannot be removed from the hole shall be perforated 7
with the exception of surface casing or any pipe already l having perforations.
- e. Cement grout having a ratio of approximately one part water to one part coment shall be pumped through a tremie pipe inserted to the bottom of the piezometer.
- f. Pumping of grout shall continue until surface returns are obtained. The grout pipe may be raised as grouting proceeds i
but must always_ be at least ten feet below the top of the grout column. Pumping shall continue while the pipe is withdrawn so as to maintain the level of grout at the top of the hole.
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C2.18. Rev. 9 l
- g. If pipe is left in the hole and grout does not return to the
. {' surface in the annular space between the pipe and the hole, the annular space shall be grouted.
- h. After grouting in the above manner, additional grout shall be placed in the hole from the surface if the level of grout
, declines before setting.
1 2. Abandonment of piezometers shall be documented and the information 4
provided to Engineering. Documentation shall include the volume of grout used, the depth, number, coordinates and ground surface elevation of the grouted hole, the date the grouting was completed and other pertinent data. The Contractor shall provide the Owner all such documentation.
- 3. For abandonment of short term piezometers, reference Paragraph C2.18.17.C.
C2.18.17 SHORT TERN PIEZONETERS A. GENERAL
- 1. Temporary piezometers will be provided in critical areas determined by Engineering to aid in the determination of the water levels in the backfill. In addition to providing data to be used in conjunction with the long teen piezometer system these temporary piezometers will quickly provide the water
( elevation in critical areas such as those where repairs are to take place or where knowledge of the water level is required in order to proceed with backfill.
- 2. The piezometers will be 4 to 5 feet deep, installed with a
, hand auger or similar device, and removed and the hole grouted when backfill is to proceed.
B. CONSTRUCTION OF SHORT TERN PIE 20 METERS
- 1. Drilling the Hole
- a. Holes shall be drilled by suitable portable devices approved by the Owners representative. Truck-mounted, trailer-mounted, or skid mounted rigs shall not be used.
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- b. Diameter of the hole shall not exceed 6 inches. Depth of hole shall be determined in the field by Owner's representative. Generally, it will be necessary to l
- penetrate approximately two feet into the saturated zone. l i
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C2.18 E:v. 9
- 2. Screen Requirements
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Screens for the short term piezometers shall be PVC of a commercial grade approved by the Owner or his representative.
Diameter of the screen shall not exceed 2 inches nominal OD.
Screen thickness slots shall not exceed .025 inches. Slots may be cut in plain PVC with a .020 .025-inch thick hacksaw blade or similar cutting device. Slots shall be cut parallel to each other and perpendicular to the screen centerline.
Slots shall be spaced 0.3 to 0.5 inches apart and their length shall not exceed 1/4 of the circumference of the pipe. No more than 3 slots shall be cut in tanden. The minimum screen length shall be 1 foot and the maximum length 3 feet. Com-mercia11y available slotted PVC screens may be substituted with the approval of the Owner's representative.
- 3. Risers The riser pipe extending from the top of the screen ~to ground level, the couplings, and the caps shall be PVC of a commercial grade approved by the Owner's. representative. The length of the riser shall be sufficient to allow a minimum 3 foot protrusion above ground surface. The exact length will be determined by the Owner's representative at the time of installation.
- 4. Backfilling
- a. Field cut screens shall be wrapped with commercial filter fabric approved by the Owner's representative, insected into the hole and the hole backfilled with material equivalent to that removed from the hole.
- b. Commercially available screens, where used shall be inserted into the hole and the hole backfilled with a properly graded filter material approved by the Owner's representative.
- 5. Surface Seal After piezometer installation is complete, the surface area immediately surrounding the PVC pipe shall be covered with bentonite drilling mud or similar impervious material to provide a seal around the standpipe.
- 6. Caps A PVC cap shall be cemented to the bottom of the piezometer below the screen. A removable PVC cap shall also be placed on top of the piezometer to prevent foreign debris from entering the standpipe.
- 7. Reference attached Sketch SK-2-C-114, Short Term Piezometer.
i 13 1
9.- ,
. C2.18. Rev. 9 i
C. ABANDONMENT OF SHORT TERN PIEZ0 METERS
[
- 1. After necessary water level data has been acquired and the short term piezometers are no longer needed, they shall be abandoned. The PVC screen and riser shall be worked icose and pulled from the hole. The backfill shall then be cleaned from the hole in the same manner as it was originally removed. The hole shall next be grouted by placing a tremie pipe to within a foot of the bottom of the hole and pumping or pouring the
- grout through the top of the tremie continuously until a
^
return flow is achieved at the surface. In~' areas where removal of the PVC riser is not practical, short term piezometers may be abandoned in accordance with Paragraph C2.18.19,I,1, b through e if approved by the Owner or his representative.
- 2. Grout six shall be approximately one part cement to one part water. Cement-sand-water mixes and/or non-shrink admixtures are permissible if approved by the Owner or his representative.
- 3. After grouting in the above manner, additional grout shall be placed in the hole from the surface if the level of grout declines before setting.
- 4. Abandonment of short term piezometers shall be documented and the information provided to Engineering. Documentation shall include the volume of grout used, the depth, number,
[
coordinates and ground surface elevation of the grouted hole, the date the grouting was completed and other pertinent data.
The Contractor shall assist the Owner in obtaining all such information as required.
D. CLEANING Cleaning and airlifting of short term piezometers shall not be performed unless directed by the Owner's representative.
Inoperative short term piezometers shall be abandoned and replaced with new installations unless otherwise directed by the Owner's representative.
E. TESTING Short term piezometers shall be tested in accordance with Paragraph C2.18.16.B.
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REVISIONS TO GROUND WATER SUPPLEMENT (APRIL 24, 1985)
4 TABLE 2-2 (continued)
OBSERVATION WELLS IN CONFINED AQUIFER Ground Top of Depth HISTORY Surface PVC Bot. of Well Installed Current Coordinates Elev.(1) Elev.(2) Marl (3) Screen Depth (3) i No. (YR) Status N E (ft) (ft) (ft) (ft) 175 1971 Crouted, 1985 8386 7363 233.1 - 164 155 - 165 (1) l 181 1971 Inactive (buried) 8144 6833 258.3 -- 194.5 190 - 200 246 1972 Crouted, 1984 10532 6553 210.4 213.5 179.7 220 - 230 Notes i'
(1) Elevations shown were determined at time of drilling.
y (2) Elevations shown are current or latest determination made prior to well abandonment.
I
$ (3) Unless otherwise indicated, depths shown were measured from ground surface at time of j drilling.
j (4) Well located in channel of Savannah River, mari not present.
i I
j (1) Revised 4/24/85 I
f 1
Water Levels #cr Well 42A Date Elevation NOTES 15-JUN-1971 141.50 --
18-JUN-1971 203.80 23-JUN-1971 141.00
. 01-JUL-1971 200.80 (1) 14-JUL-1971 188.80 21-JUL-1971 179.10 04-AUG-1971 113.50---
11-AUG-1971 109.00 18-AUG-1971 104.70 25-AUG-1971 102.90 01-SEP-1971 102.00 08-SEP-1971 103.20 15-SEP-1971 101.30 28-SEP-1971 102.50 29-SEP-1971 81.50 06-0CT-1971 93 30 23-0CT-1971 93.30 02-NCV-1971 97.20 -
10-NOV-1971 96.20 17-NOV-1971 98.00 23-NOV-1971 99.70 01-DEC-1971 100.90 07-DEC-1971 101.00 14-DEC-1971 101.20 23-DEC-1971 100.70 29-DEC-1971 102.50 05-JAN-1972 99.50 12-JAN-1972 98.80 19-JAN-1972 101.10 26-JAN-1972 99.00 03-FES-1972 100.40 09-FES-1972 99.70 23-FES-1972 101.70 02-MAR-1972 100.70 09-MAR-1972 100.70 16-MAR-1972 100.70 21-MAR-1972 101.50 18-APR-1972 101.20 26-APR-1973 108.40 30-MAY-1973 103.50 27-JUL-1973 110.50 13-0CT-1973 108.10 0 3-N O V-197 3 107.80 09-3EC-1973 107.30 07-JAN-1974 108.00 10-FE3-1974 104.60 23-MAR-1974 105.80 17-APR-1974 109.60 NOTE:
(1) These data not valid. The measurements represent water in the well used in construction and development, not aquifer water g level,s. (Revised 4/24/85)
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j 4.0 STATUS OF DRILL HOLES i
In response to the request for a discussion of the status of the 474 holes referenced in FSAR Section 2.5.4.3.1 and any holes in addition to i
these (letter from E. G. Adensam to D. O. Foster, dated February 19, l
I 1985), the following discussion and accompanying tables are submitted, i
i i
4.1 Holes Penetrating the Blue Bluff Marl
- All of the holes that were drilled through the water-table aquifer, the
- Blue Bluff marl, and into the underlying confined aquifer are listed on Table 4-1. The status of each hole is also shown. It is normal practice
. of the engineering firms conducting the drilling of exploratory holes to fill them with grout following their completion, unless they are utilized as an observation or production well. Table 4-1 includes 17 active wells. Eine are active ground water observation wells open to the confined aquifer. There are four production wells open to the unnamad Lisbon sand (Tertiary), three of which supply construction water and one supplies water for the Simulator Building. In addition, four wells are (}
completed as production wells open to the deeper Tuscaloosa Formation (Cretaceous); two are plant operation make-up wells, and two are wells originally planned as make-up wells, but are presently planned not to be utilized. Observation well 181 is currently inactive. This well is
(
scheduled to be abandoned (grouted) in the near future.
I All observation wells monitoring the unnamed Lisbon sand (Tertiary
{ aquifer) were sealed in the Blue Bluff mael with cement grout during well (1) construction to prevent communication between aquifers.
(1) Revised 4/24/85
All of the remaining holes on Table 4-1 were for exploratory purposes
, only. There is documentation that all of the holes were grouted except g) 236, 237, and 239. Although there are no data to indicate the exact disposition of these holes, it is believed these were also grouted.
The grouting method used for sealing all holes, exploratory, seismic, and i observation wells is the same. The method employed is conunonly known as
! the "tremie method", which is performed by insertion of a small diameter
!- pipe (drill rods, 1/2 to 1-inch steel or pVC, etc.) to near the bottom of
.i
~
the hole and pumping cement slurry through the pipe, filling the hole from the bottom up. Grouting continues until grout appears at the top of the hole. This method is employed to assure that the hole is completely grouted and no volds are present. l 4.2 Other Holes in the Confined Aquifer Seversi exploratory holes were drilled through alluvium of the savannah River flood plain into the confined aquifer, but did not penetrate the i
marl. As discussed in the FSAR, the Bbte Bluff marl is not present beneath the flood plain of the river. All of the holes on Table 4-2 were drilled in the flood plain into the confined aquifer. The area is
- strat1 graphically below the bottom of the mael.
l 1
of these holes, two were completed as observation wells, one of which was grouted in 1985 because its location interferred with construction of the river facilities. The other is a flowing well that has been capped and.
equipped with a pressure sage for monitoring.
(1) Revised 4/24/85 i
.. - - . . _ . - . --,,__..2- . . , _ _ _ _ - . _ _ _ - , .
There is documentation that hole 123 was grouted to elevation 29 feet but there is no documentation as to the final completion or abandonment of the remaining holes. The grouting method for sealing observation well 121 and hole 123 was the tremie method as discussed in Section 4.1.
4.3 Holes Drilled only into the Unconfined Aquifer or River Alluvium Holes penetrating only the unconfined aquifer or the river alluvium are shown on Table 4-3. Thirty of these holes were completed as observation wells to monitor the unconfined aquifer, thirteen of which are still in use. Of the remaining seventeen, 10 have been grouted, leaving seven that are inactive but with no documentation concerning the method of abandonment.
One of the wells, PW-1, is the water supply well for Plant Wilson.
Included in Table 4-3 are a number of wells constructed as temporary observation wells in the backfill at the Powerblock excavation. These wells (LT and ST series) were installed to monitor the water level in the backfill as backfilling operations were conducted to assure that the 1
(1) Revised 4/24/85
TABLE 4-1 HOLES THAT PENETRATg BLUE BLUFF MARL AOUICLUUs l
(Drilled into confined aquifer) l i
1 Hole Hole Number Status Number Status l
1 Grouted 107A Grouted 2 Grouted 109 Grouted
- 3. Grouted 111 Grouted 5 Grouted 111A Grouted 6 Grouted 113 Grouted 7 Grouted 114 Grouted 8 Grouted 114A Grouted 9 Grouted 116 Grouted l 10 Grouted 119 Grouted 11 Grouted 122 Grouted 12 Grouted 132 Grouted 13 Grouted 133 Grouted ;
14 Grouted 134 Grouted 15 Grouted 135 Obs. well, grouted 16 Grouted 136 Grouted 17 Grouted 137 Grouted 18 Grouted 138A Grouted in ear 1**
19 Grouted 139 Grouted 20 Grouted 144 Obs. well, grouted 21 Grouted 144A Grouted 22 Grouted 145 Grouted 23 Grouted 147 Obs well, grouted 24 Obs. well, grouted
- 152 Grouted 4
25 Grouted 156 Grouted 26 Obs. well, grouted 157 Grouted l(2) 27 Obs. well, active 170 Grouted 29 Obs. well, active 175 Obs. well, grouted 31 Obs. well, grouted 180 Grouted 32 Obs. well, grouted 181 Obs, well, inactive 33 Obs. well, grouted 182 Grouted 37 Grouted 202 Grouted 38 Grouted 203 Grouted in earl 39 Grouted 204 Grouted in earl 40 Grouted 216 Grouted 42 Grouted 217 Grouted 42A Obs. well, grouted 218 Grouted i 425 Obs. well, grouted (1) 219 Grouted 42G Obs. well, grouted (1) 220 Grouted in earl 45 Grouted 221 Grouted ,
101A obs, well, grouted 222 Grouted 4 102 Grouted 223 Grouted 102A Grouted 224 Grouted l 104A Crouted 225 Grouted 105 Grouted 226 Grouted 106 Grouted 227 Grouted 107 Grouted 228 Grouted
! (1) Not drilled into confined aquifer, screened in marl aquielude.
l, (0632g) (2) Revised 4/24/85
TABLE 4-1 (Continued)
HOLES THAT PENETRATE BLUE BLUFF MARL AQUICLUDE (Drilled into confined aquifer)
Hole Hole Number Status Number Status 229 Grouted 502 Grouted 230 Grouted 503 Grouted 235 Grouted 503A Grouted 236 No closure record 504 Grouted 237 No closure record 505 Grouted 238 Grouted in earl 506 Grouted 239 No closure record 507 Grouted 243 Obs. well, grouted 508 Grouted 244 Obs, well, grouted in marl *** 509 Grouted 245 Obs. well, grouted 510 Grouted 246 Obs. well, grouted 511 Grouted 247 Obs. well, grouted in marl 512 Grouted 248 Obs. well, grouted in earl 513 Grouted 249 Obs. well, grouted in marl 514 Grouted 301 Grouted 515 Grouted 302 Grouted 516 Grouted 303 Grouted 517 Grouted 304 Grouted 518 Grouted 305 Grouted 519 Grouted 306 Grouted 520 Grouted 307 Grouted 521 Grouted 308 Grouted 522 Grouted 309 Grouted 523 Grouted 310 Grouted 524 Grouted 311 Grouted 601 Grouted 312 Grouted 603 Grouted 313 Grouted 605 Grouted 314 Grouted 607 Grouted 316 Grouted 609 Grouted 319 Grouted 609A Crouted 322 Grouted 610 Grouted 324 Grouted 611 Grouted 326 Grouted 613 Grouted 329 Grouted 615 Grouted 331 Grouted 617 Grouted 333 Grouted 619 Grouted 334 Grouted l(1) 621 Grouted 335 Grouted 623 Grouted 336 Grouted 624 Grouted 337 Grouted 625 Grouted 338 Grouted 627 Grouted 339 Grouted 629 Grouted 408 Grouted 631 Grouted 409 Grouted 633 Grouted 501 Grouted 702 Grouted 501A Grouted 704 Grouted (0632g)
(1) Revised 4/25/S5 o
i )
TABLE 4-1 (Continued) , m.
l HOLES THAT PENETRATE BLUE BLUFF MARL AQUICLUDE (Drilled into confined aquifer) i 4 Hole Hole Number Status Number Status 705 Grouted P-5 Grouted 705A Grouted RF-1 Grouted i 1 706A Grouted RF-1 Grouted l 707 Grouted RF-2 Grouted 709 Grouted RF-3 Grouted i 711 Grouted RF-4 Grouted l
'712A Greuted RF-5 Grouted I
'713 Grouted RF-6 Grouted 850 Grouted RF-7 Grouted 850A' obs, well, active RF-8 Grouted 851 Grouted RF-9 Grouted
- 851A s;0bs. well, active CW-1 Construction well, active
- 852 obs. well, active CW-2 construction well, active 853 Obs, well, active CW-3 construction well, active j 854 Obs. well, active MU Make-up well, activa 855 Obs. well, active MU-1A M"..ke-up well, grouted l(1) 856 Obs, well, active MU-2~ Make-up well, active F-1 Grouted MU-2A.' Make-up well, active P-2 Grouted SB-1 '- ' Simulator bldg. well, P-3 Grouted active '
P-4 Grouted TW-1 Test well, active
- Obs. vell, grouted - hole was complettd as observation well.
Observation well was grouted at later date.
- Grouted in earl - hole was drilled through marl. Marl was grouted before hole abandoned. ,
- '- Obs well, grouted in earl - hole was drilled through marl. Marl was
' grouted and hole completed as observation well open to unconfined aquifer. +
i i
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(06323)
(1) Revised 4/24/85
- ._ . _ _ . _ _ _ _ _ _ - _ _ . _ - - _ _ _ . _ . _ . _ _ - _ - _ . _ . - _ - _ _ - _ .