Soils percolation testing apparatus

A soils testing apparatus has a hollow shaft for insertion into a test hole and includes vertically adjustable wedging blades slidable and T-tracks on the shaft for centering alignment in the test hole. A hand pump evacuates water from the test hole to a predetermined null point whereupon vertical movement of a float and float rod supported and guided within the shaft over a finite period of time will yield a direct percolation absorption rate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to soils percolation testing apparatus and more 
particularly relates to improvements in the art of determining the liquid 
absorptive rate of soil sites under investigation or examination. 
2. The Prior Art 
The prior art is characterized by large clumsy devices four inches or 
greater in diameter and requiring a power source, timers, recording media 
and they operate on the concept of recording the drop in water level over 
a finite period of time. 
SUMMARY OF THE INVENTION 
The primary objective of this invention is to provide an inexpensive, 
rugged, easily employed, highly accurate device for determining the liquid 
absorption rate of soils. 
A small cylindrical shaft is secured in a test hole and is adjustably 
positioned with the use of vertically slidable blades so that it is 
virtually centered in an upright position. An integral hand operated pump 
is used to set the top of a float rod to a zero or null position, 
whereupon a time measurement is taken and after a predetermined time 
interval correlated with a calibrated scale, a direct reading of the 
absorption rate is obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Although details of the present application can be varied dimensionally 
without departing from the principles of the present invention, a 
preferred embodiment will be described with the use of actual dimensions 
as utilized in an exemplification of the inventive subject matter. 
Thus, referring to FIG. 1, a soils testing apparatus constructed in 
accordance with the present invention is shown disposed in a typical 
placement within a test hole. The apparatus comprises a 2 inch (5.08 cm.) 
diameter cylindrical shaft 1 which may be made of a suitable rigid plastic 
material. 
The shaft 1 is approximately 36 inches (91.44 cm.) in length and forms a 
housing in which there is disposed a round buoyant float 5 which may also 
be made of a suitable plastic material, for example, the float 5 may be a 
hollow plastic molding. The float 5 is attached to a float rod 6, which 
may be formed as an extrusion from an acrylic plastic material. In the 
exemplification of the present embodiment, the float rod 6 is 0.125 inches 
in diameter (32 mm.) and 34.625 inches long (87.95 cm.). The upper 6 
inches (15.24 cm.) is preferably a distinctive contrasting color, for 
example, a red color. 
The float rod 6 is enclosed by a 0.375 inch (95 mm.) outside diameter clear 
extruded acrylic guide tube 3 which is particularly characterized at its 
upper end by a tube 15 which is approximately 6.5 inches (16.51 cm.) long 
and 0.625 inches (1.59 cm.) outside diameter marked with indicia means 
forming a graduated scale indicating the exact percolation rate calibrated 
in terms of time measured in minutes for 1 inch (2.54 cm.) of water to be 
absorbed by the adjacent soil. 
Referring to FIG. 6, the calibrated scales are illustrated. It will be 
noted that the scale on the left of FIG. 6 designates so-called 30 minute 
readings while the scale on the right hand side of FIG. 6 is calibrated 
for 10 minute readings. 
In order to facilitate the ease of reading the percolation rate, a 
magnifying lens 16 is provided which is approximately 5 inches (12.7 cm.) 
long and is juxtaposed to the end of the float rod 6 and through which the 
end of the float rod 6 may be viewed relative to the graduated scales on 
the guide tube 15. 
Referring to FIGS. 1 and 5, it will be noted that the entire upper assembly 
is enclosed and protected by a globe-like cap 17 made of an opaque plastic 
and having a cylindrical body portion which terminates in a rounded 
spherical dome at its uppermost end. The cylindrical body illustrated is 
approximately 3 inches in diameter (7.62 cm.) and is approxi-mately 9 
inches (22.86 cm.) in longitudinal dimension. The bottom end of the 
cylindrical body portion of the cap 17 is formed with internal screw 
threads 17a for effecting screw threaded engagement with external screw 
threads 14 a formed on the external flange 14b provided on a cover member 
14 which fits over the top end of the shaft 1. 
At the lower end of the float guide tube 3 there is provided a spacer 4 
which is more particularly shown in FIGS. 3 and 4 in conjunction with FIG. 
1. Thus, the spacer 4 made of plastic is essentially a flanged disc 
approximately 2 inches (5.08 cm.) in diameter and through which extends a 
centrally disposed opening 4a and four radially outwardly 
circumferentially spaced openings 4b, each being approximately 0.375 
inches in diameter (95 mm.). The spacer 4 functions to hold the lower end 
of the tube 3 in proper position. 
In accordance with this invention, the apparatus is also equipped with a 
hand operated suction pump shown generally at 13 and comprising a 
rubberized hollow bulb 13 a having the usual air check valve integrated in 
the end thereof as at 13b. The bulb 13a is connected to a flexible plastic 
tubing 12 which, in turn, is connected to a rigid suction tube 2 by way of 
an elbow 11. The tube 2 is disposed to extend generally downwardly on the 
outside of the shaft 1 and is of sufficient length to reach within 6 
inches of the bottom of the shaft 1. Positioned at the lower end of the 
suction tube 2 is a foot valve 2 a with a strainer 7 which will maintain 
zero leakage. 
In order to align the apparatus in a test hole accurately and quickly, the 
device of the present invention is particularly characterized by the 
utilization of three equiangularly spaced blades 9 carried and positioned 
in complementary shaped T-tracks 10 fastened in firm assembly with the 
outside surface of the shaft 1. Each blade 9 is a plate-form element 
having an upper edge 9a disposed at approximate right angles to a 
longitudinal edge 9b having a T-flange 9c formed thereon or attached 
thereto, and which has a sliding insert fitting relationship with an 
adjoining T-track member 10 having a T-shaped recessed track 10a formed 
therein to receive the corresponding flange 9c. The front edge of the 
blade 9 is a piloting edge 9d which tapers downwardly and inwardly and 
terminates in a bottom edge 9e disposed at right angles to the 
longitudinal edge 9b. Thus, as the device is placed into a test hole, the 
piloting edges of the blades 9 guide the apparatus into a properly 
centered upright position. 
In order to properly ventilate the apparatus, an air vent hole 18 is formed 
by drilling and is located at the top of the shaft 1. 
In operation, the percolation testing procedure is as follows: 
First of all, a test hole 19 is dug in the site under investigation or 
examination approximately 4 to 12 inches (10.16 cm. to 30.48 cm.) in width 
and to the depth of the proposed absorption field, which is generally 24 
inches (60.96 cm.) The bottom and the side walls of the test hole 19 are 
carefully scratched with a knife blade or a similar sharp pointed 
instrument in order to remove any smeared soil surfaces and to provide a 
natural soil interface into which water may percolate. All loose material 
is removed from the test hole. To protect the bottom of the hole from 
scouring and sediment, 2 inches (6.08 cm.) of coarse sand or fine gravel 
as shown at G is added. 
The test hole 19 is then preconditioned or saturated by filling the hole 19 
with clear water to a minimum of 12 inches (30.48 cm.) above the 
protective layer G and is maintained at such level overnight, or for at 
least a period of 4 hours. After completion of the saturation period, the 
water level is adjusted in the test hole to approximately seven inches 
above the gravel G. Thereupon, the apparatus including the shaft 1 is 
inserted into the test hole 19. The plastic blades 9 are inserted into the 
T track 10 and are vertically adjusted by engaging the wedging edges 9d 
against the sides of the test hole 19. 
After securing the instrument properly in the test hole 19, the hand-held 
suction pump 13 is used to accurately set the top of the float rod 6 and 
the percolation rate scale 15 to 0 by carefully exhausting some remaining 
water in the test hole to approximately six inches above the gravel G. The 
time is recorded accurately and after a 30 minute period, the 30 minutes 
scale 15 is read. The reading is the desired absorption rate needed for 
design purposes. 
In sandy soils or in such soils in which the first 6 inches of water seeps 
away in less than 30 minutes after the four hour saturation period, the 
time interval between measurement should be taken at approximately 10 
minutes and a test run should be undertaken for one hour. The drop that 
occurs during the final 10 minutes is read on the 10 minutes scale 15 and 
is the desired absorption rate to be used for design purposes. 
Although minor modifications might be suggested by those versed in the art 
it should be understood that I wish to embody within the scope of the 
patent warranted hereon all such modifications as reasonably and properly 
come within the scope of my contribution to the art.