ML20065C805
| ML20065C805 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 09/09/1982 |
| From: | Bourquard E E.H. BOURQUARD ASSOCIATES, INC. |
| To: | Wescott R NRC |
| References | |
| NUDOCS 8209240311 | |
| Download: ML20065C805 (18) | |
Text
So - M yo - 3 5 3 E. H. BOURGIUARD ASSO CI ATES, I N C.
WATER RESOURCES ENGINEERING wAt ER suPety rLOOo CONTROL PROJECTS WACTEWATER DisPLesAL 1400 RANDOLPH STREET DAME & RESERVOIRE WATER RESOURCES IEme? No. 24, $wYEneTATE G3)
DR AIN AD E*STO RMwATER HYDRAULAG STUDIEE H ARRessunO. PA, NYDROLOulQ STUDIES rLOOD INSURANCE STUDIES 17104*3497 ENVIRONMENTAL STUDIEW TELEPHONE (717) 238 9505 September 9, 1982 Mr. Rex Wescott, U.
S.
Nuclear Regulatory Commission, 7920 Norfolk Ave.,
Bethesda, MD 20014.
Re: Bradshaw Reservoir and Pumping Station
Dear Mr. Westcott:
In accordance with our phone conversation today, enclosed are the following:
1.
Bradshaw Beservoir Specification Section 02220, Earth l
Fill.
J 2.
Soil Testing for Engineers, Lambe, Chapter VI, Permeability Test.
Item 1 specifies the requirements the Contractor must follow in construction of the earthen dam and impervious liner.
As we diccussed, there will be no specific permeability requirement for the Contractor to meet. However, the material as specified should provide a maxim 0m in place permeability of 0.000005 cm/sec.
In the unlikely event the material would exceed this permeability, bentonite would be incorporated into the liner material as neces-cary to reduce the permeability.
Since the need for bentonite is i
unlikely, it has not been included in the Specification.
If 4
needed, the additional work would be carried out under a Contract i
change order.
Item 2 describes the permeability test procedure.
Tests will be conducted at the Contractor's proposed off-site borrow area on the natural undisturbed material and also on the liner after compaction.
Undisturbed samples will be taken at both l
locations.
The variable head method will be used.
l l
Sincerely yours, i
[
Robert H.
Bourqu d
RilB/bs 3OOl Encl. As Noted c.c. Dave Morad, PECO w/ encl.
8209240311 B20909 PDR ADOCK 05000352 A
PDR l
j
6
.,.y 9 1982 SEp SECTION 02220 EARTH FILL PART 1 GENERAL 1.01 WORK INCLUDED A.
Construct earth embankments and other earth fills re-quired by the Drawings and Specifications.
1.02 RELATED WORK A.
Section 02210:
Salvaging and Spreading Topsoil.
B.
Section 02211:
Excavation.
C.
Section 02265:
Water for Construction.
D.
Section 02266:
Removal of Water 1.03 REFERENCES A.
ASTM D698 - Moisture Density Relations of Soils and Soil-Aggregate Mixtures Using 5.5 lb. (2.49 kg) Rammer and 12-in. (305 mm) Drop.
PART 2 PRODUCTS 2.01 MATERIALS A.
On-site Borrow Areas.
1.
Obtain suitable fill material from required excava-tions and designated borrow areas.
B.
Off-site Borrow Areas.
1.
Locate a suitable off-site borrow area (s), notify the Owner of its location and arrange for entry to f
the site for testing and sampling.
Provide the l
necessary excavating equipment and labor to permit the procurement of soil samples considered repre-sentative of the borrow material proposed for use.
l The Owner will perform all field and laboratory i
testing of the material to determine its suitability l
for construction of the required fills.
l 2.
If in the judgment of the Owner th e ma t'e r i a l is suitable, the Contractor shall furnish such material i
from the approved off-site borrow area (s).
In the event the material is not suitable, the Contractor l
shall locate an additional borrow area (s) and the l
process repeated until an approved borrow area (s) is l
located.
02220 -1 812 J
'ee 3.
It shall be the contractor's responsibility to locate the borrow area (s), purchase the material, furnish such material to the site, place and compact such material in accordance with the specifications and meet all governmental requirements.
4.
Impervious Material.
a.
Off-site borrow material for reservoir embank-ment or impervious liner construction shall be suitable impervious, inorganic, fill consisting of uniformly-graded silty clays and clayey silts with the amount of friable rock fragments not exceeding more than 20 percent of the total mass, but 6veraging eight (8) percent or less.
Soils classified as impervious fill shall con-tain at least 65> percent, by weight, of materi-al finer than the No. 200 mesh sieve with the average percent passing the No. 200 mesh sieve being at least 80 percent.
All soils shall be classify as ML, CL or ML-CL types according to the Unified Soil Classification System (USCS).
They shall not have a liquid limit (LL) exceeding 50 and shall have plasticity indices (PI) ranging from at least two (2) to a maximum of 22.
No cobbles, boulders or otherwise durable rock fragments having a maximum dimension in excess of four (4) inches shall be included in the impervious fill.
In addition, the impervious fill materials, when subjected to the Standard Compaction Test, ASTM Desig-nation 698, latest edition, shall indicate a maximum dry density at the optimum moisture l
content of at least 107.0 p.c.f.
(pounds per
)
cubic foot).
All fill materials, regardless of type or source shall be free of topsoil, wood, lumber, roots,. grass, rubbish, metal, organic content, or other deleterious material.
j b.
All "off-site" material proposed for use as impervious fill shall require demonstration of suitability by grain size distribution, plasti-city and compaction tests, the results of which must be first approved by the Owner.
c.
If during the excavation and hauling of the impervious fill from the approved borrow pit it l
becomes apparent that the appearance and char-l acteristics of the fill material change to an extent readily noticeable by visual inspection, a complete classification and new compaction control curve will be obtained.
If such addi-tional testing indicates the material ~does not meet the previously approved kind, a new source shall be immediately located by the Contractor I
which shall be tested and approved-prior to the material being hauled to the project site.
02220 - 2 812 i
T Ps m
C.
Fill Material.
1.
The selection, blending, routing and disposition of materials is subject to the Owner approval.
2.
Material to be free from sod, brush, roots and rock particles larger than 3 inches.
1 PART 3 EXECUTION 3.01 FOUf!DATION PREPARATION A.
Strip foundations to remove vegetation, topsoil and other unsuitable materials.
3.
Grade founiation surface to remove irregulari, ties and scarifice parallel to the axis of the fill to a minimum depth of 2 inches.
Control the moisture content of the loosened material as specified for the earth fill.
C.
Compact and bond the first layer of earth fill with the surface materials of the foundation.
D.
Clear loose material from rock foundations by hand or other effective means.
Remove standing water from rock foundations before placing fill.
3.02 PLACEMENT OF FILL A.
Complete the required excavation and founda' tion prepar-ation prior to placement of fill.
B.
Do not place fill on a frozen surface nor incorporate snow, ice or frozen material in the fill.
C.
Place fill in approximately horizontal layers not more than 8 inches before compactica.
D.
Uniformly spread materials in piles or windrows to not more than 8 inches in uncompacted thickness before com-paction.
E.
Spread material to be hand compacted or compacted by manual directed power tampers in layers not more than 4 inches thick before compaction.
F.
Adjacent to structures, place fill in such a manner to prevent damage to the structures and to allow the struc-tures to assume the loads from the fill gradually and uniformly.
Increase the height of the fill at the same rate on all sides of the structure.
Do not place fill against structures before the time interval listed below.
'ee 02220 - 3 812
/
/
i
Structure Time Interval 1.
Retaining walls 14 days 2.
Walls backfilled on both sides simultaneously 7 days 3.
Conduits and spillway risers, cast in place (with inside forms in place) 7 days 4.
Spillway risers (inside forms removed) 14 days 5.
Conduits, precast, cradled 2 days 6.
Conduits, precast, bedded 1 day 7.
Antiscep collars 3 days G.
Place fill for earth fill dams, levees and other struc-tures designed to restrain the movement of water in accordance with the following requirements:
1.
Place fill so that the distribution of materials throughout each zone is essentially uniform.
Fill to be free from lenses, pockets, streaks, or layers of material differing substantially in texture or gradation from surrounding material.
2.
If the surface of any layer becomes too hard and smooth for proper bond with the succeeding layer, scarifice it parallel to the axis of the fill to a depth of not less than 2 inches before the ncxt layer is placed.
3.
Maintain the top surface of embankments approxi-mately level during construction.
Provide a crown or cross-slope of not less than 2 percent to insure effective drainage.
If the Drawings or Specifica-tions require or the owner directs that fill be placed at a higher level in one part of an embank-ment than another, maintain the top surface of each part as specified above.
4.
Construct dam embankments in continuous layers the entire length.
Openings may be provided to facili-tate construction or to allow the passage of stream flow.
5.
If an embankment is built at different levels, pro-vide a maximum slope of 3 to 1 at their junction.
j
- Strip the bonding surface of the higher embankment l
of all loose material and scarifice, moisten the soil and recompact when new fill is placed against it to insure a good bond between the two fills and to obtain the specified moisture content and de.
in the junction.
3.03 CONTROL OF MOISTURE CONTENT i~w A.
Moisture content of the material at the time of compac-tion to be not more than 3 percentage points above or one percent below the optimum moisture content.
Soils con-taining free water or soils having moisture contents greater than a moisture content midway between the liquid j
and plastic limits for the material are considered too 02220 - 4 812
i..~*
wet for placement in the embankment.
If they are used, dry prior to placement.
Accelerate drying action by discing, harrowing, or manipulating to the extent neces-cary to reduce the moisture content to within the speci-fled limits.
When the material is more than one percent-age point below optimum, wet the material by sprinkling uniformly, and disc or harrow to obtain uniform distribu-tion of the moisture content to within the specified limits.
B.
Scarifice and dry or moisten the previously placed layers when necessary to produce a suitable bond for the suc-ceeding layer.
3.04 COMPACTION A.
When the moisture content and condition of the layer is l
satisfactory, compact by tamping rollers to a density of at least 95% of the maximum density as determined by ASTM D698.
B.
Tamping rollers to consist of one or more heavy duty double drum units with a drum diameter of not less than 60 inches.
The drums to be capable of being ballasted.
Each drum to have staggered feet uniformly spaced over the cylindrical surface such as to provide approximately three tamping feet for each two square feet of drum sur-face with the distance between the feet equal to or greater than 9 inches.
The tamping feet to be 8 to 10 inches in clear projection from the cylindrical surface of the roller and to have a face area of not less than 6 nor more than 10 square inches.
The roller to be equipped with cleaning fingers, so designed and attached as to prevent the accumulation of material between the tamping feet.
The weight of the roller to be not less than 4,000 pounds per foot of linear drum length aal-lasted, and not more than 3,250 pounds per foot o' drum length empty.
The loading to be such as to obtain the specified compaction.
The roller to be pulled by a crawler-type tractor of sufficient power to operate the roller at a speed of approximately 3\\ mph.
C.
Use power driven hand tampers, vibratory or other satis-factory tampers to tamp around structures or other loca-tions where larger rollers cannot satisfactorily compact l
the material.
D.
Compaction rollers of other designs may be used after approval by the Owner provided the requirements for compaction and other specified requirements are met.
02220 - 5 812
8 e
3.05 PE*DVAL A';D PLACE'iE';T OF DEFECTIVE FILL A.
Pemove or rework fill placed at densities lower than the specified minimum density or at moisture contents outside tha specified acceptable range.
3.06 TESTING A.
During the course of the work, the Owner will perform such tests as are required to identify materials, to determine compaction characteristics, to determine mois-ture content, to determine permeability and to determine density of fill in place.
These tests performed by the Owner will be used to verify that the fills conform to the requirements of the Specifications.
Such tests are not intended to provide the Contractor with the information required by him for the proper execution of the work and their performance shall not relieve the Contractor of the necessity to cerform tests for that purpose.
END OF SECTIO:1 02220 - 6 812
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CHAPTElt VI L
L Permeability Test e
introduction is sensitive to changes in temperature. Equation VI-3 A humhed years ngo, Darcy showed experiinentally expreknes the relationship between viscu3ity and per-l water y flowmg through soil of cross-meability.
L,-
that the tate f piopoitional to the imposed
- 3. The void ratio of the soil. The major influence acetional area A
,v n s gradient i or of v"id ratio on permeability is di3eus3ed later in this f
q chnpter.
L.--
~~i y - LiA t 7% shapes and arrangernent of pores. Although permtability depends on the shapes and arrangement f
L-
"I P. ores, this dependency is difEcult to express mathe-The coetEcient of proportionality k has been called "l)arey's coefficient of liennenbility" or "coefEcient of inntienlly.
permeability" or "permeabihty." $ TLu3 pennenbility i The degree of saturation. An increase in the de-
[,
in a soil property which indicates the case with which gree of saturation of a soil canses an ir. crease in per-water
- till flow through the evil.
meability. This eficet is illustrated by Fig VI-1.
Penneubility enters all problems involving flow of For testing sands and silts, the normal procedure is water through sods, much a3 ocepage under dam 3, the first to determine, by laboratory tests on distmbed upicezing out of water from a soil by the application samples, the relationship of void ratio to permea-of a load, and drainage of subgrades, dain.x, and back-bility. After obtaining the in situ void ratio of the
~~
lilla. As will be disennel in later chaptein, the clree-
, oil, we can predict the in situ pernmdsility by n,ing tive ettength of a soil is of ten indheetly controlled by the void ratio-penneability curve determined in the f-its penneability, laboratory. This procedure is the mm,t feasible one l
l'enneability depends on a number of factors. The j,eca u3e of the difEculty of obtaining undisturbed main ones ine:
mples of cohesionless soils. It should be remem-g l
- 1. The size of the soil grains. As pointed out on bered, however, that many soils have widely different '
i l' age 30, permeability appears to be proportional to permeabilities along the stratificaticn and perpen-the siunre of an effet tive grain =ize.
This propor-dicular to it, and, therefore, the reaults obtained on f
l tmnality is due to the fact that the pote dize, which is di3tmhed samples umy be of little real significance.
v the primasy vatiable, is nelated to particle size.
The penneability of an undisturbed sample of clay 1
> The properties of the pore /Inid. The only im-can be detennined diseetly at sevend different void poilant variable of water is vincosity, which in imH ratios while running a consolidation test, as described i The t ho r t on.oc u<.1 interthangeably, eva thon,th the in Chapter IX.
u,e heie of ".oi thcient" may be ques oncil. The coe ffkitut is At least four laboratory meti;od:, of measuring the not. tin,tn.ionlew. but he the unita of veloi ny.
penoeability of a soil are available. The variable The soil engineer onely deals woh pne finnis other than w,a t r.
Ilowever, the i.cnneabihty of a a, oil cua al3o be ub.
" Very hequently the g.tancabihty ulung the strutifaution is y
hi.unt for finiits much us oil.
five to fdty tiines us large as that rrow it.
52
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l'ermenhility Test.
53 3
' Clmp. VI) f head nnd constant head tests are presented in this
- 2. Standpipe
~~l thnpter. The rapillarity method is ' presented in
- 3. Deniring and saturating device J
Chapter Vill; the use of consolidation test data to
- 4. Support frame and clamps compute permeability is discussed in Chapter IX.
h rd The variabic head test is normally more convenient
- 1. %,mulen haimner
~"
i for cohes.mnless sm.is than the constant head test be-
- 2. Bell j.ar for constant head chamber cause of the simpler.instrmnentat. ion. There are ron-
- 3. Supply of distilled, dem. red water ditions, however, mulcr which the constant head te t
- 4. \\,acuum supply for example, for the tests on partially
- 5. Balance (0.1 g sensitivity) is preferable:
- 6. Drying oven 60 l
l l
- 7. Desiccator
- Franklin Fans in 10"cm/sec
- 8. Scalc
{"', '[5 [ 3 d(" 5lC
- 9. Thermometer (0.1* sensitivity) 70 p
- ~.,
Ouena in 10"cm/sec
- 10. Stop clock "j
- 11. Rubber tubing
- 12. Evaporating dish 60
,l Un on Fans sand f
- 13. Funnel c = 065 J
- 14. Pinch clamps u
4
+
[50
~
Figure VI-2 is a diagrammatic sketch of a variable head test setup which has proved satisfactory. In 3
..a i40 the laboratory, the parts can be permanently mounted to a panel or simply held to a support frame by nhn Faus C
E Fort Peck sand 5
' " 0 58 N
/
c O 73 clamps. The use of a transparent material, such as
[
M e, h h p u w W aM waW ch m W h 30 ott,,,,,,o
, = 0 48 %
highly desirabic, because it facilitates the mansure-g ment of the length of soil sample, L, and aids the de-s a
g tection of any air bub,bles or inovement of soil fines 2D M
during the test. Likewise the water level in a trans-E*"*"
- U """
1.0 ing of the soil length can be further facilitated by the 70 80 90 100 Degree of saturationin%
cementing of graph Imper strips, with units of length W
Facum VI-1. Permeabihty s crsus degree of satmation for marked on them, to the outside of the permenmeter.
various sands. (Data from reference VI-G.)
It is good policy to number each permenmeter and standpipe, and mark on each its cross-sectional arca, saturated soils (discussed in Chapter VIII) and for The bottom screen m the permenmeter should be nt-i direct permeability determinations in conjuncton with tached by some type of inside wedge and not screws, consolidation tests (discussed in Chapter IX) on cer-since screw holes are a possible source of Icaks when
.u tain soils.
the permenmeier is evacuated.
L Apparatus and Supplies
- The tubing should be either metal, high-pressure rubber (see Fig. VI-2), or some other matcrial which Variable IIcad Test can resist the applied vacuum. If low-pressurc tub-Special ing is used between the standpipe and the permeam-
- 1. Permenmeter tube.
eter, it will decrease in diameter as the hydrostatic (a) Two screens pressure decreases because of a lowering of the water (b) Two rubber stoppers P
(c) Spring level in the standpipe. To prevent errors from such volume changes, the amount of tubing in this connec-l'
- The npparatus for thin test in desciibed in more detail than tion should be kept tu a minimum. Water traps.m for mome of the other tests because it is more of ten constincted k'
in the soils habmatcry from i.tock mateii d3.
the line preceding the manoincters arc desirabic to r
- The desiinble size of a permeameter depends on the soil to prevent water from flowing into the manometers dur-be tested. Permesuneters in the neighborhood of 4 cm in di-ing the saturating process.
ameter and 30 cm long have been found satisfactory for many p.3
- A dediocator may not be needed. See page 10.
soils. See page SS.
4
.)
51
[ Chap. VI l
S..il Te-iin::
L-
, The rhoice of standpipe size thoubt he inade with listed for the vnriable head te3t. The additional items l
oy.ruil lo. fl.o e. oil to be inled. l'or a roruse sand, a itepend..n (Lc type of setup nacil.
I' niundpipe whose diurneter is approximately equal to in Fig. VI-3 are shown diagrammatically two test L r-that of the permenmeter is usually satisfactory. On setup > for running the constant head test. Althoueh I
f i
b-To distdied l water suppff t
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c::-@c 1)'-Water traps
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Manometer Manometer-.
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Thermometer
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P f ermcameter 4
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Constant L' '-
head chamber Fn.ein. VI-2. Setup for vioi.ilile i.emi pennealdlity test.
i the other haml, fine silta may necessitate a standpipe the one on the left is simpler, it should be used only j
whose aliameter is one-tenth or less of the permeam-for soils of high permeability. This limitation is duc eter diameter.
to the fact that, if the soil is relatively impermeabic, l
Co n,.ia n t IIcad Tet.t.
There are several items the rate of flow is low, and thus the loss of water by needed for the constant head test in addition to those evaporation can become an important consideration.
l I
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2 Chap. VI)
Permeability. Test 55 The balloons (Fig. VI-3b) furnish a convenient be applied to the water to obtain the ndditional head means of preventing evaporation. If the air inside sometimes needed for testing impermeable soils, them is allowed to become saturated with water vapor prior to te ting, tui cvaporation will occur dur-llecommended I'rocrelurc ?
,j ing the te>t (unless the atinospheric picsuure or tem-The detailed procedures described below are for pcrature changes). The halloons shoubt he kept very soils which are cohesionless; permeability determina-1 Innse so that the preuure in them will be essentially tions on fine-grained soils arc discussed in Chapter IX.
. j atmospheric.
If the diameter of the water supply bottle (Fig.
Variable IIcad Test
.]
VI-36) is large relative to the diameter of the per-
- 1. Measure the inside diameter of the standpipe and j
incarneter, the value of h can usually be considered permearneter.
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Water E-C9 f
surply l __~_ __-
i Water
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Thermcmeter f
'l Thermometer l<
D~ 7 l
s JhFermeameter Perrneameter
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~.~1 7 area = A 4
area = A ".;
h' 4
- e Balloon I
gl L__.
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h-Constant I
} [- ~ GU@- [ head chamber i
3-, :j a
s a
3 -Graduate Constant f n
head chamber
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.:= :.
Graduate s,5 hi l
p._
(a)
(b)
Fmvin: VI-3. Setup for consinnt hnal pennenbility test.
t J
constant for a test The water level in the bottle
- 2. Obtain to 0.1 g the weight of the empty per-should be recorded at the start and completion of the menmeter plus screens, stoppers, and spring.
test to check the degree of validity of this assump-do's this test for the first time shouh! be able 7
tion. The use of a bottle for tbc water supply has s
to test a cohesionless sua at three or four void ration in 2 to two advantages; it is n convenient means of storing 3 hems and do the cornputahons in nbout nn hour. He prob.
watcr between tests, and it easily permits pressure to nbly will need supervision for the first part of the test.
~
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[ Chap. VI L.
Soil hiing 56 well as in the line from the permeameter into the con-p
- 3. Luni the permenmeter with dry soil' to a loose, stand head chamber.
mdform density by pouring the soil in."
- 12. Itegin ilm test by opening valve p; start the timer 4.1%ce the top neicen, npdng, mnf a u o -hippi r in the tube. The spring thould be compres3rd 30 that it as the water level falls to hoand reconi the einpsed times when the water level reaches V/d and h. Stop the i
will apply n prernre to the soil aml help 1.cep it in by closing p.
flow af ter the level passes h i place when it i.4 daturated.
- 13. Obtain temperature readings at the 1.ead water r
- 5. Wei:b the filled pernicameter; the difference be-eml of the sunple anil in the const:mt head chamber.
[
l tween the two weight 3 is the muount of soil used.
- 6. Place the filled permeameter in position for test-11 Compare the elapsed time required for fall from ing as shown in Fig. VI-2.
ho to V'hdo with that for V4olo to h." If these i
- 7. Evacuate the smnple to an absolute }uessure of time.s (L rt agice within 27o or 3% reldl and rerun."
only a few centimeters of Ilg by the following, method:
- 15. When a goul run has been obtained, decrease to) Clone all valven shown in Fig. VI-2.
the void ratio by tapping the side of the permeameter (h) (1 pen valves g, h, j, /:, f, c, d, e, and b.
with the wooden hammer.
S. Af ter waiting some 10 to 15 minutes for the re-
- 10. Itemea3me the sampic length and obtain time moval of air, saturnte the soil by the following oh.scrvations for the falling head in the standpipe as was done for the pievious void ratio.
Inethod; (u) Close valves f, g, and h.
Conniant IIeml Test r
(b) Open valve n. The water will enter the toil
- 1. Phtee the soil in a measured permemneter, weigh, because of the capillary attraction aided by the dif-and saturate as in the varishle head test (steps 1-SL ference in elevution between water chamber and
- 2. Measure the value of the head, h, and specimen r-If more head difference is needed, it perineameter.
The length, L.
can be obtained by slightly opening vent m.
- 3. Start, flow by opening valve a (see Fig. VI-3),
difference in readings of the two manometers will
- 4. After apawing a few minutes for equilibrium indicate the additional prewure head that is thus to be reached, obtain graduate and time conditions obtamed.
readings.
(c) Allow the water to saturate the sample and
- 5. After a sutlicient amount of water has collected i.
I rise up to valve 6, then close n.
in the graduate for a satisfactory measure of its Sub-(d) llelease the vacuum on the sample by first volume, take graduate amt time ob3crvations.
tract the graduate and time readings obtained in closing k and d, and then slowly opening y and m.
(c) Any air hubble in the permeameter above "l'P.4 from the respective values obtained in this step the soil should he removed by slightly opening the to give Q and I for lui. Yl-2.
upper stopper while applying water through q, with
- 6. Itecord the temperature of the water every few
{-t' d clo3ed. Any bubbh:.m the hnttom should be re-minutes.
moved tlovugh s, while applying water through n
- 7. Change the void ratio of the soil as was donc in l
of the variable head test, and take another series with m open.
th Mea,me the length of sample L and hicate and gmdnate mid time readings. Measure the specimen measme the heads ho and h. The top limit of ho is length at each void ratio.
i y
selected at the upper end of the standpipe; 4 a few 3
centimeters above the lower end of the standpipe; the Ilicem sion of Procedure
~
1)cgree of Saturation. In the preceding procedure, head Vholy should be marked on the standpipe.
an attempt was made to get the soil completely natu-
[~
i
- 10. With valves n and d clused, fHl the standpipe with datilled, deaned water to an elevation which is a ygy r
few centimeters above ho by opening valves y, c, and a.
y 8
d,A
- An l
Chne valve c; leave a open.
d li"#" 'A",uld be equal laanse uns odan tunis in
- 11. Check to.sce that there is no air in the hoe be-f d'P d
A lack of agreement tween the standpipe and permeameter up to valve c, as hq. VI-l ;oe constant for any given run.
Imre touhl be due to lents, incomplete satmation, movement g
of fines, f ui eign matt er in water, or water not nulficiently
- Sce page % (m a dis nwion of the masinnnn grain size wini h whonhl be used.
de:o r nl.
" pom mg the soil intu the permentneter lemia lo canw degie-
'l INen though the Linies for die two dericIbents nrc in agice-
}
l Srgirgation enn he m[niinized by placing the noil with ment. it is u guuJ policy to anale a check run (ace Numcrical gabon.
d h*
a.3 mall r.m lint to nu mg3 m auth n way that it can be lowcs e Landsle).
into the proutumeter und then ciulined.
I t-l i
a
=
7*
Clmp. Yl]
Permeability Test 57
,}
rated because the permeability of an "almost satu-in the water wouh! have to be prevented as it Ilmved
]
rated" soil may be considerably different from its from its storage supply through the soil. This is he-J saturated " value. Figure VI-1 illustrates this point.
cause the solubility of air is proportional to the pres-To obtain a high degree of saturation, use a vacuum sure of the air above the water for small pressures apinoaching absolute zero. For example, Fig. Yl-1 (11enry's law, VI-3) ami decreases with tempeinture d
shows the iciationship between the decree of vacmon as shown by Fig. VI-5. The soinhility of air in water for evacuating a certnin fine sand and the iesulting may be altered by other changes in the water as it 9
degice of saturation. In this ca-c an applied vacuum flows through the soil; for example, the dissolving of j
of at least 27 or 28 in. of mercury was necessary to any solubh salts from the soil.
get a high degree of saturation.
To pf event, any air from coming out Of kulution, The water used for saturating the soil shouhl be two luocedures are reconnnended. First, keep the almost completely deaired, because if there is innch temperature of the water a few degrees warmer than the soil and tubing, if this is done, the water will f
cool as it flows, tims slightly inercasing its capacity 200 for di solving air. This procedure is known as " main-Atmosphenc r passure taining a favorab!c temperature gradient." Second, u+ waler which has less than its capacity of air dis-g solved in it ; such water is commonly called "deaired" g
s go a
5 water.
3 3
30 -
3
'o es F 80 r.a 20 P
\\
70 0
-10
-20
-30 5
\\
Apphed preuure in mches of Ug Fmo.ir. Yl-1.
(Fiom icierence VI-l.)
{
nir dissolved in the water, most, of it will be brought j
10 r
out of solution by the high vacuum used for the satu-rating process of step 7 (see page 50). The deairing p
of the saturating water, however, presents no problems
(
in the apparatus shown in Fig. VI-2. In fact, the pro-c.,
[
redure described in step 7 applies a vacuum to the l
water in the " distilled dcalled water chamber" from o
IS f's which the saturating water is thawn. A vacuum can D:ssolved air per I cc wbter in cc at 0*C and 760 mm
!j he kept on the water in this chamber when the ap-W.iMy of air in water. Nute: Air lo e of p
y paratus is not in use.
CO2 and Nila. ti)ata funn Introurtinnul Critical Tubirs, Air dissolved in the water used for the actual per-Voi.111.)
a y
meability test causes no trouble in normal testing as I)caired Waler. The air dissolved in water can he l
long as it does not ecme cut of solution to collect in j
the tubing or to collect in the soil, thus decreasing its removed by increasing the temperature or decreasing j
degree of saturation. If water saturated with air wrre the pressure. Boiling can reduce the dissolved air in l
used, a risc in temperature or a decrease in pressure water to about 0.75 ppm of oxygen or 1.5 cc of mr."
Water which ha< heen deaired is slow in regaining its y
y As liscuwd in Chapter Vill, natura' soils ilo not nere"-
air, as evidenced by Fig. Vl-0, which is a plot " of sanly cwt m a satuiated state. Caiciul rontrol of the degree of saturation, however, is irquired in order to obtain tat data n One ppm of oxygen in air dissolved in water corresponds f'
ulm h ran be reproduced. Also, the pennenbility of a soil when npproximately to 2.0 cc of nir at 700 mm piessure and O' C per saturated in a loniting vnhic niul, therefoie, is of unpoilance 1000 cc of water.
(=ec Chapter Vlli). Unfortunately, these nic ;.crmcability test
" This is a plot of data from a research proicct in the Ily-pnw edures in use which do not control, or escu mensme, the draulits 1.aborntury at M.I.T. The data were obtained by the depre of saturation, incichrywiropping clectrode system the rc:ulings ucre taken at 91
,' 5 11.
- Soil hting
[ Chap. VI l
oxygen pick-up against elapsed time for a vessel of the chance of f aige voids forming where the particles 4
deaired water whose surface was exposed to the air.
touch the wall of the permeameter. Keeping the ratio r
Figure VI-G shows that at the end of 13 days the water of the permeameter diameter to the diameter of the
[.-_.
was only 00%. saturated. More clahorate methods for largest soil particle greater than about 15 or 20 has j
deniring and storing water are available (VI-2), but been found satisfactory. This limits the soil tested in j
~
they me not thought necessary for normal permen-the 4-em permenmeter suggested on page 53 to that hility te> ting. Iloited di-tilled water is satisfactory passing a No. 8 or No.10 sieve. A larger perme-for mo.st permealjihty testing for some time af ter ameter should be used to test a coarser soil.
r If the soil tested is too coarse, the flow will be tur-
[.-
I bulent rather than Imninar. Laminar flow is assumed 5
/j
-c--
in Darcy's law, by which Eqs. VI-1 amt VI-2 are
~
deiived. For the normal test setup, laminar flow exists
-l
[4 7
only in soils finer than coarce sands. The error ap-
/~~
s ij pearn small, however, in using Darey's law on soils
{
3 whose pattieles are a littic larger than coarse sand.
- c..-
g Crmlient increase by Gas l'rcosure. To increase g,
r=2Vc At satation, dissolved osygen m 8 4 pprn the rate of IloW in the conatant, head tCsting of soils of low permeability, a gas pressure can be applied to e
the surface of the water supply. (When a pressure 0
40 80 120 100 200 240 280 320 300 is uwd, it is advisable to cover the surface of the Elapse:d tirnein hours water supply with a membrane of some sort to reduce Ficuni; VI-6. Pick-up of oxygen t>y water.
the amount of gas going into solution.) The head boiling. The water shouhl not be agitated and should lost is then h (Fig. VI-3) phis the applied pressure be covered to prevent the collection of foreign matter changed to units of water head. Pressure is often f tom the atmosphere. Water can easily be covered cinployed for permeability determinations on consoli-by stoppering the storage vessel and venting it with dation specimens (Chapter IX).
a tube whose end is pointing downward, as illustiated Calculations in Fig. VI-7.
Figure VI-7 also > hows the recom.
mended manner to tap the water supply; the water at Variable llem! Test the bottom of the ves>el tends to contain less dissolved The coellicient of permeability k can be compute 1 nir than that at the top.
from al 3 ho a
n k = 2.3 logio A (Vl-1) e i
A(ti - to) i in which a = eross-sectional area of the standpipe, vent L = length of soil smnple in permeameter, Y
Y A = cross-sectional area of the permeumeter, when water in standpipe is at ho, a
to = time 3 = time when water in standpipe is at h,
i
/
i.E.M 1
5 55 ho, hi = the heads between which the permeabil-ity is determined (see Fig VI-2).
-_ ~ ~ ~_ _ ~ _
M
~~-
Constant llend Tc.t h
The cuellicient of permeability k can be computed j
t --
imm Fu.cuc VI-7. Stonge of walet for penneahdity tests.
QL I
"U
.Tlaximum Crain Sise. To limit the maxiinum L
grain size of the soil tested to some reasonable frac-in which Q = total quantity of water which flowed tion of the dire of the permeameter is desirabic. The I
ilu ough in elapsed timc4 t,'
use of large particles in a sinall permeameter increases h = tot:d head lost (see Fig. VI-3).
a point % in, below the air-water intur.ue in a ve..,et 5% in.
"If the time is started at zero when the water in the stand-s in itinna.ter und % in deep. The sate of air ph I.-up i= ichied t o the autiu of opuant suiface inca over vohi.. uf the w.aler, pipe is at hu, then tu is equal to xcru.
i t
b
Chnp. VI]
I'erancability Test 59 l
1.14; I._.
1 10
.4 l 06
....t 7
1.02
'8 O 98
- *l o
- J kx.
E
\\
..l.
b 0.94
\\
N\\
~
0 90
'-N\\
\\
0 86
.e N
0 82
.a 0.78 i
15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
'..s Temperature in C y.-
Fwrun VI-S. (Data isonn intowstinnni Critical Tal>les, Vol. V.)
The permeability at temperatme T, kr, can be re-Itesults f
k-6 duced to that at 20' C, k:o.c, by using M d hod of' l'resen t a t ion. The results of a perme-ability tedt are usually presented in the form of a plot Mr ko.c = kr (VI-3) of some function of void ratio, c, against some function of permeability, h n*c.
Often two plots are made:
- 2 '
2 in which k.c = permeability at temperature 20 C, k vs. e /(1 + c), c /(1 + c), and e' on one sheet and 2
20 kr = permeability at temperature T.
c vs. log k. The best relationship of the above four is
- r = viscosity of water at temperniure T then used to present the results of the test (see discus-(see Table A-3, p.148),
sion below).
~
- 20 c = viscosity of water at temperature Typical Values. The permeabilities of several soils 20* C (see Table A-3, p.148).
are given in Fig. VI-1. A better indication of typical permeabilitics can be obtained from the classification A plot of pr/F20 c against temperature is given in of soils based on their permeabilities which is given P
Fig. VI-8.
helow (VI-5).
..a e
Y1
Soil hiing
{Cliap. VI I
t,0, w
l A in er,.in,,eters graded, coarse sand, which was used for the shel! of an vegre,,.f l>rr,urut,g.ty pe scem,J c.o th dam. The plots of data in Fig. VI-9 show that 9
C*/ I I + ") h 'dion-t inoluniinnat to k nini doit the et
_y a
- t., unn i., t log L curve is ahnust a straight line. According n,,
jo-sto30-6 vs.
very I. w 10-5 ta 10-'
to the classification given under Typical Values, this
[
Praetumny iinin rnwahle I.e than 10-2 si>il windd he called one of medium permeability.
L-- -
A permeabilit y of 1 y per occond (104 cm per second) is fiequently used as the hoiderline betwe en pervious HEFEllENCES I
L nml impervious doils. Thus a soil with a permeability
- 1. Ainerienn Society for Testing Materiids,
- Procedures for less than 1 p per becorni nu. ht be considered for a dam
,rnt uig Sods," Phil.ulel.la.a, Pa.,., uly,10',0.
g i
c tote ur impervious blatiket, whence.3 une with a per-
- 2. Ileitoun, G. E., "An Experiinental Investigation of Protec-ineability greater than 1 p per setuint might be con-tive Fihets. flartiard University Publiention No. 267,
'- l -~ "
r.idened for a dam shell or pervious backfdl.
1939-1910.
Dine n nesion. lloth theoretienlly and experiinentally 3 Mill.ini, E II, P/4ysical Cl.cmistry for Collcoes, McGraw-
{
these ii more justification for e /(1 + e) to be pro-t hil liuol Co, New Yoik saul 1.orulon,191ti.
d
~1 I'" int t, !!. It., anil N. E. Pdirson, "Expciiinental Invc3ti-pin tional to L than for cilher c /(1 + c) or c" in the 2
M"li" 'I 'I'e Degia of Saunahun in Runta," Maan of
- of rare of cohesion!ce doils. f.aboratory tests on all Scirnte Thesis. Dep.atinent of Civil Engineering, Massa-types of duils Imve shown that a plot of vo. t rat.
n m
i.lai<sts Inshtute of Teila,olon,1918.
ver3ns lug of pertucabil.ity := noually close to a diraight
- 5. Teiragla, IL, nnd it. II. Peck, &al Mecluo,ics in Enginecr-IIHC-i,,u Practic c, John Wiley ornt Sons, New York,1918.
- 6. Lilate, M. I,"Experinnental Investig. tion of the Elicct of
,'%, nnerient l, mnplc Ikgree of Saturation on the l'ermenhility of Sand,"
a S " '1 In the exninple un pages G1 arnt G2 are presenteil the Master of Sciente Thesi., Depaitinent of Civil Engineer-lesults of n variable head pertocability test on a well-ing, Manachu3ctts Institute of Technology,1918.
l.
I I
iW
-.i l
1
.y l
L-r -- -
W
-t 1.
F a
1 1
43 t'
-t--
I l
j
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m