Granular type structure with moisture retaining top surface

The disclosure is directed to a built-up granular structure having a stable moisture content controlled upper layer. The preferred granular structure includes an improved fine aggregate upper surface layer, a coarse aggregate reservoir layer having a topmost application of perforate adhesive material, and a dry moisture barrier layer having a topmost impervious layer. The entire layered structure is supported by any firm base including compacted soil or an existing playing court structure. A containment wall having screened drainage inlets/outlets surrounds the periphery of the structure.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a built-up playing court structure, 
enabling a selected moisture content to be maintained within its surface 
layer, and a method for its construction. 
2. Description of the Related Art Includinq Information Disclosed Under 37 
C.F.R. 1.97-1.99 
There are at present two basic types of surfaces used for playing courts, 
"hard" surfaces and "soft" surfaces. Hard surface courts generally have 
concrete and asphalt surfaces and, indoors, wood surfaces. Soft surface 
courts generally have lawn, clay and various composite built up surfaces. 
To effectively play court games, one is required to repeatedly turn and 
move with rapidity. One of the primary disadvantages of the use of hard 
surface courts is that the bones, muscles and connective tissues of 
players are stressed by repetitive activity on the hard surface. 
Conventional soft surface courts however, also have disadvantages. 
Construction and maintenance costs are typically very high. Frequent 
cutting, rolling, smoothing and replenishing of the surface materials is 
required to keep the surface in a playable condition. Additionally, since 
most of these soft surface courts are constructed outdoors, and are 
porous, water retention following ambient rainfall may preclude play on 
the court surface due to puddles or a general muddy court surface having a 
slippery consistency. 
Built-up playing courts consisting of gravel, sand, clay and various 
bonding materials have been developed in the art as a more practical 
alternative to conventional clay courts. A clay or sand top surface layer 
is desirable, because such a layer makes a surface more playable by 
providing smoothness yet appropriate traction for the soles of players, 
shoes. However, there are several problems inherent in such conventional 
built-up surfaces. Loose sand or clay which is normally present at the 
uppermost surface layer over time, washes down through the lower layer 
materials, such as gravel, due to rain or sprinkling; this sand or clay is 
thus lost from the surface and has to be periodically replaced. Drainage 
of such courts presents a problem because the sand or clay tends to fill 
all of the void spaces between the lower surface materials (e.g. gravel). 
Thus, water will not drain laterally below the surface at a sufficiently 
fast rate. Hence, water drainage usually runs off over the top surface, 
gradually removing the surface materials. Even if the surface materials 
are not washed away, they tend to be redistributed unevenly, causing 
smoothing problems. Furthermore, unless the surface is adequately sloped 
and almost perfectly uniform, there will be standing puddles of water 
following rains which will preclude use of the court until the water is 
removed by evaporation. Almost all conventional soft surface and hard 
surface courts have a slope in an attempt to prevent puddling. Another 
problem occurs in cold weather areas. Water trapped within the void spaces 
below the surface freezes. The expansion that takes place during freezing 
causes movement of the surface, thereby damaging it. Repair is necessary 
to smooth the damaged areas. Another problem is that wind tends to blow 
away or unevenly rearrange surface materials, especially when the surface 
is dry; again, requiring replacement or smoothing. This problem could be 
alleviated considerably by sprinkling the surface with water. However, 
during periods of winds or play, sprinkling is impractical. Another 
problem with wind is that the top surface tends to dry out, resulting in 
poor footing for the players and inconsistent ball bounce. 
Since court games, particularly tennis, are played by millions of people, 
much time and energy has been devoted to solving such problems inherent in 
maintaining outdoor athletic courts or similar structures. Examples of 
proposed solutions to some of the problems are disclosed in U.S. Pat. Nos. 
585,856, entitled Underground Irrigation, to Swanson; U.S. Pat. No. 
3,307,360, entitled Method of Subsurface Irrigation and System Therefor, 
to Bailly; U.S. Pat. No. 3,625,010, entitled System and Method for 
Preventing Erosion, to Hakundy; U.S. Pat. No. 1,222,648, entitled Growing 
Trough, to Marks; U.S. Pat. No. 2,031,146, entitled Automatic Watering 
Device, to Dodge; Czechoslovakian Patent No. 111978 to Sramek; Italian 
Patent No. 482615 to Ortensi; German Patent No. 27 27 956, to Blank; U.S. 
Pat. No. 1,862,423, entitled Playing Court, to Otto; U.S. Pat. No. 
1,958,850, entitled Tennis Court, to Foster; U.S. Pat. No. 4,015,432, 
entitled Stabilizing Subsoil Moisture Under Light Structures, to Ball; 
U.S. Pat. No. 1,690,020, entitled Pavement and Process of Laying Same, to 
Kirschbraun; U.S. Pat. No. 2,024,158, entitled Playing Court, to 
Gallagher; U.S. Pat. No. 4,044,179, entitled Playing Surface for Athletic 
Games, to Haas, Jr.; U.S. Pat. No. 3,908,385, entitled Planted Surface 
Conditioning System, to Daniel, et al.; and U.S. Pat. No. 4,576,511, 
entitled Apparatus and Method of Creating and Controlling an Artificial 
Water Table, to Vidal, Jr. None of these patents teach the unique court 
surface structure of the present invention having a built-up court surface 
layer, a stabilizing subsurface layer, and means for selectively 
controlling moisture content in the built-up court surface layer. These 
patents are discussed in more detail below. 
The '856, '360, '010, '648, '146, patents and Czechoslovakian Patent No. 
111978, disclose subsurface irrigation devices. The irrigation systems are 
used for providing water to a vegetative or natural soil surface cover. 
Italian Patent No. 482615 and German Patent No. 27 27 956 disclose a 
subsurface irrigation system for sports fields with granular surface 
covers. The '432 patent discloses a subsurface moisture barrier. 
The '020, '158 and '179 patents disclose permanent, fixed surfaces. The 
'020 patent is directed to a combined bituminous and concrete pavement 
surface. The '158 patent teaches a playing court surface atop cork/sand 
gravel beds. The '179 patent discloses an artificial turf fabric surface 
which is intended to simulate grass. 
The '385 patent discloses a system for irrigating and evacuating a playing 
field having a vegetative cover. This system incorporates a lattice of 
perforated pipes under the playing surface. The pipes are covered by a 
layer of sand followed by a layer of rooting media on which the vegetative 
matter is grown. A pump attached to the pipe lattice allows a vacuum to be 
applied and accumulated surface water to be drawn down within the 
subsurface sand layer. Also incorporated into the system is a moisture 
sensor which allows automatic irrigation of the field. 
The '423 patent discloses a soft surface court having a pervious surface 
layer which enhances drainage and moisture retention, depending upon 
ambient conditions. The '850 patent teaches the use of fine epidote as a 
top layer and coarser epidote as a lower layer for a tennis court surface. 
Neither of these patents provide means for moisturizing the surface. 
The '511 patent discloses means and apparatus for maintaining a selected 
water level in a layered structure of particulate material. 
RELATED APPLICATIONS 
Prior application, U.S. Pat. No. 4,881,846, entitled BUILT-UP PLAYING COURT 
STRUCTURE AND METHOD FOR ITS CONSTRUCTION, to Burkstaller, et al., filed 
Mar. 28, 1988, the teachings of which are incorporated herein by 
reference, relates to a built-up, moisture content controlling playing 
court structure comprising a built-up court surface layer; a barrier 
surface substantially impervious to moisture spaced beneath the built-up 
court surface layer; a containment wall positioned essentially 
peripherally about the built-up court surface layer and the barrier 
surface and extending upwardly from the barrier surface to about the level 
of the built-up court surface layer disposed thereabove; a subsurface bed 
of aggregate disposed atop the barrier surface and beneath the built-up 
court surface layer, the aggregate bed being peripherally surrounded by 
the containment wall; and means, preferably piping, for controllably 
introducing liquid to and draining liquid from the subsurface bed of 
aggregate and the built-up court surface layer to substantially maintain a 
selected moisture content in the built-up court surface layer. Moisture 
content in the surface layer of parent application, U.S. Pat. No. 
4,881,846, is controlled by maintaining an appropriate liquid level in the 
subsurface bed, thereby providing upward movement of moisture by capillary 
action or wicking to the top surface layer. The moisturizing rate, which 
can be controlled to be essentially equal to the evaporation rate, is 
determined by the liquid level and the particle sizes in the subsurface 
bed. 
Co-pending application filed concurrently herewith, entitled IMPROVED 
MOISTURE RETAINING TOP SURFACE FOR A BUILT-UP GRANULAR STRUCTURE AND 
METHOD FOR ITS CONSTRUCTION, to Burkstaller, et al., the teachings of 
which are incorporated herein by reference, discloses a surface for 
built-up granular structures. This surface is useful in the present 
application. 
SUMMARY OF THE INVENTION 
The invention relates to a built-up, moisture content controlling granular 
structure and method of construction. The preferred structure comprises an 
upper surface layer comprising fine aggregate material; a barrier surface 
substantially impervious to moisture spaced beneath the upper surface 
layer; a containment means positioned essentially peripherally around the 
structure; a subsurface reservoir bed disposed atop the barrier surface 
and beneath the upper surface layer, the subsurface reservoir bed being 
peripherally surrounded by the containment wall; and means for stabilizing 
the subsurface reservoir bed and for providing adequate fluid conductivity 
between the subsurface reservoir bed and the upper surface layer to 
substantially maintain the selected moisture content in the upper surface 
layer. 
The upper surface layer comprises fine aggregate, such as igneous, 
metamorphic, sedimentary, and synthetic materials. The preferred fine 
aggregate is primarily volcanic material or a mixture of granite, marble, 
quartzite, and limestone, although basalt, felsite, rhyolite, augite, 
olivine, biotite, silica, obsidian, tuff, volcanic ash and dust, 
agglomerates, latite, monzanite, dacite, granodiorite, andresite, dorite, 
dolomite, marble, mica, feldspar, quartz, calcite, gabbro, syenite, 
diorite, gneiss, schist, or mixtures thereof are also useful in accordance 
with the invention. 
The stabilizing and fluid conductivity providing means preferably comprises 
a stabilizing layer of adhesive material disposed atop the subsurface 
reservoir bed. This layer of adhesive material comprises voids therein to 
provide adequate fluid conductivity between the subsurface reservoir bed 
and the upper surface layer thereabove to substantially maintain the 
selected moisture content in the upper surface layer. The upper surface 
layer of fine aggregate material is preferably disposed atop and in the 
voids of the adhesive coated stabilizing layer. 
The structure may comprise a support bed of aggregate disposed beneath the 
barrier surface. The barrier surface comprises an intermediate stabilizing 
layer disposed atop the support bed of aggregate. This intermediate 
stabilizing layer may comprise an adhesive material, preferably with voids 
therein to provide supportive stability to the support bed of aggregate 
and adequate fluid conductivity between the subsurface bed of aggregate 
and the support bed of aggregate to maintain selected moisture content in 
the structure. Alternatively, the adhesive material may be a solid layer 
substantially free of voids or the barrier surface may comprise a solid 
layer, such as a plastic sheet. 
The structure may further comprise means for controllably introducing fluid 
to and draining fluid from the subsurface bed of aggregate and the upper 
surface layer to substantially maintain a selected moisture content in the 
upper surface layer. This fluid controlling means preferably comprises 
surface watering means, such as sprinklers, conduit disposed between the 
upper surface layer and the subsurface bed of aggregate, or surface 
flooding means. The surface flooding means may also serve as drainage 
means. The subsurface reservoir bed in the structure preferably comprises 
coarse aggregate, a mortar material, preferably comprising a mixture of 
cement, sand and water, wherein the proportion by volume of cement to sand 
is approximately one part cement to 10-20 parts sand, or a mixture 
thereof. 
The present invention further provides a method of constructing a built-up, 
moisture content controlling granular structure comprising the following 
steps obtaining a foundation for the granular structure; providing a 
moisture barrier above the foundation; providing a containment wall 
peripherally about the foundation; providing a subsurface reservoir bed 
above the moisture barrier; providing an upper surface layer comprising 
fine aggregate atop the subsurface reservoir bed; and providing means for 
stabilizing the subsurface reservoir bed and for providing adequate fluid 
conductivity between the subsurface reservoir bed and the upper surface 
layer to substantially maintain the selected moisture content in the upper 
surface layer. 
The method may further comprise the steps of providing a support bed of 
aggregate beneath the barrier and controllably introducing fluid to and 
draining fluid from the subsurface bed of aggregate and the upper surface 
layer to substantially maintain a selected moisture content in the upper 
surface layer. 
A primary object of the present invention is to regulate the moisture 
content in the surface of a granular-type built-up structure. 
Another object of the invention is to provide a surface of consistent 
quality. 
A further object of the present invention is to provide a built-up granular 
surface which is inexpensive to construct and maintain. 
One advantage of this invention is that in accordance therewith, surface 
runoff during rain can be greatly reduced to essentially eliminate washing 
away and puddling of the surface. 
Another advantage of the invention is that wind erosion is substantially 
reduced by providing moisture to the granular surface at all times, 
including windy periods. 
Yet another advantage of the invention is the elimination of costly and 
complicated moisturizing and drainage apparatus. 
Other objects, advantages and novel features, and further scope of 
applicability of the present invention will be set forth in part in the 
detailed description to follow, taken in conjunction with the accompanying 
drawing, and in part will become apparent to those skilled in the art upon 
examination of the following, or may be learned by practice of the 
invention. The objects and advantages of the invention may be realized and 
attained by means of the instrumentalities and combinations particularly 
pointed out in the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
The present invention relates to a built-up granular structure having a 
system for controlling the moisture content of the playing surface and the 
court structure. The invention can be utilized in the construction of new 
structures or to convert or retrofit existing structures, such as playing 
courts. 
FIG. 1 shows a preferred built-up granular structure 10 in accordance with 
the present invention comprising an upper surface layer 12, a perforate 
adhesive layer 16 below the upper surface layer 12, a coarse aggregate 
reservoir layer 14, an intermediate imperforate adhesive 18, a support 
layer 20, and a base 21. A containment wall 22, with screened drainage 
outlets 46 therein, surrounds the periphery of court structure 10. The 
present invention incorporates the invention described in prior 
application, U.S. Pat. No. 4,881,846, entitled BUILT-UP PLAYING COURT 
STRUCTURE AND METHOD FOR ITS CONSTRUCTION, to Burkstaller, et al., filed 
Mar. 28, 1988, with the differences or improvements being the use of 
surface moisture control instead of subsurface moisture control, the use 
of an intermediate adhesive elastomer layer or moisture barrier layer, and 
the use of a mortar material in place of the adhesive elastomer layer. The 
present invention also includes the surface materials disclosed in detail 
in co-pending application filed concurrently herewith, entitled IMPROVED 
MOISTURE RETAINING TOP SURFACE FOR A BUILT-UP GRANULAR STRUCTURE AND 
METHOD FOR ITS CONSTRUCTION, to Burkstaller, et al. 
Referring now to FIGS. 1 and 2, the preferred upper layer 12 of the 
improved structure 10 is disclosed in co-pending application filed 
concurrently herewith, entitled IMPROVED MOISTURE RETAINING TOP SURFACE 
FOR A BUILT-UP GRANULAR STRUCTURE AND METHOD FOR ITS CONSTRUCTION, to 
Burkstaller, et al., although other surfaces may be employed, such as 
disclosed in prior application, U.S. Pat. No. 4,881,846, entitled BUILT-UP 
PLAYING COURT STRUCTURE AND METHOD FOR ITS CONSTRUCTION, to Burkstaller, 
et al., filed March 28, 1988. That upper layer 12 provides a simple yet 
effective surface of fine aggregate. Both drainage and moisturization of 
this improved upper surface layer are accomplished by controllably 
introducing fluid directly at this surface either manually, by automatic 
sprinklers, or by any other direct surface watering means; that is, no 
expensive and complicated subterranean piping or drainage system is 
required. The upper layer may be level so drainage takes place at the 
periphery of the upper surface layer. The relative size proportions of 
fine aggregate in the upper surface layer provide a bonding effect when 
moisturized, resulting in a court surface having increased "playability." 
Nevertheless, the high retained moisture content of the surface also 
provides a safety margin in that safe footing is provided, decreasing the 
possibility of knee and ankle injuries. Any desired thickness may be used 
to accomplish the desired moisture content of upper layer 12, although it 
is preferably between approximately 1/4 inch and 1/2 inch thick. Reference 
is made to co-pending application filed concurrently herewith, for a 
complete description of the preferred upper surface layer. 
In the preferred embodiment, shown in FIG. 1, a perforate adhesive 
elastomer layer 16 is disposed immediately below surface layer 12, and 
above reservoir layer 14. This substantially impervious adhesive layer 
locks substantially closely spaced and touching coarse aggregate particles 
26 disposed in the reservoir layer 14 together, while permitting free 
percolation of moisturizing liquid or fluids therethrough. This adhesive 
coating or layer 16 preferably comprises polyurethane, epoxy, rubberized 
asphalt, or a mixture thereof. This adhesive layer is discussed in detail 
in prior application, U.S. Pat. No. 4,881,846, entitled BUILT-UP PLAYING 
COURT STRUCTURE AND METHOD FOR ITS CONSTRUCTION, filed Mar. 28, 1988, and 
co-pending application filed concurrently herewith, entitled IMPROVED 
MOISTURE RETAINING TOP SURFACE FOR A BUILT-UP GRANULAR STRUCTURE AND 
METHOD FOR ITS CONSTRUCTION. 
The reservoir layer 14 itself, in the preferred embodiment shown in FIG. 1, 
comprises a mixture of coarse aggregate 26 and fine aggregate 28, such as 
sand and gravel. This layer provides a reservoir function; water 
percolates upwards and downwards between the upper layer 12 and this 
reservoir layer 14. Depending upon the desired moisture content of the 
upper layer 12, the fine aggregate 28 of the reservoir layer 14 allows for 
saturation of the reservoir layer 14. The uppermost coarse aggregate 26 
particles in the reservoir layer 14 are secured together by the coating of 
adhesive elastomer 16, creating an adhesive foraminous elastomeric layer 
or a web-like layer. The interstices or voids 30 between the coarse 
aggregate particles 26 in the reservoir layer 14 are filled with fine 
aggregate 28; the fine aggregate 28 is not coated with the adhesive 
elastomer 16, thus allowing the free percolation of water between the 
upper layer 12 and the reservoir layer 14. The voids 30 in the reservoir 
layer 14 containing the fine aggregate 28 are saturated with fluid, thus 
not only storing fluid, but providing supportive stability to the coarse 
aggregate 26 in this layer 14. The fluid moves upwardly by capillary or 
wicking action and downwardly by gravity. Obviously, the moisture content 
of the upper surface layer 12 can be controlled by maintaining a selected 
degree of liquid saturation in the reservoir layer 14. The reservoir layer 
14 also provides support for the upper layer 12. This reservoir layer 14 
is discussed in detail in prior application, U.S. Pat. No. 4,881,846, 
entitled BUILT-UP PLAYING COURT STRUCTURE AND METHOD FOR ITS CONSTRUCTION, 
filed Mar. 28, 1988, and in co-pending application filed concurrently 
herewith, entitled IMPROVED MOISTURE RETAINING TOP SURFACE FOR A BUILT-UP 
GRANULAR STRUCTURE AND METHOD FOR ITS CONSTRUCTION. 
Several alternatives exist as to the exact composition of the reservoir 
layer 14. As noted previously, the coarse aggregate and fine aggregate 
mixture, discussed above, may be used. The reservoir layer 14 may be made 
of any thickness, depending on the need to more rapidly absorb excess 
water. The preferred thickness of the reservoir layer 14 is less than one 
inch. 
In an alternative embodiment for the reservoir layer 14, shown in FIG. 2, 
the adhesive layer 18 and the sand-gravel aggregate, shown in FIG. 1, can 
be eliminated and replaced by a mortar mixture 34. This mortar mixture is 
preferably a weakly consolidated cement-sand-water mixture. The preferred 
mortar mixture comprises ten to twenty parts sand by volume to one part of 
Portland cement. All the heretofore described functions of the reservoir 
layer 14 would still accrue: reservoir layer stabilization, moisture 
retention, storage for a desired volume of moisturizing fluid for the 
upper layer, moisture transfer between the upper layer and reservoir, and 
support of the upper layer. One advantage to this mortar material is that 
no perforate adhesive layer is required. 
As shown in FIGS. 1 and 2, underlying the reservoir layer 14 is an 
intermediate imperforate moisture barrier 32. This moisture barrier 32 in 
FIG. 1 is shown as a solid adhesive layer 18 and as an impermeable sheet 
36, such as a plastic sheet, in FIG. 2. If an adhesive elastomer is 
utilized as the moisture barrier 32, the preferred materials are 
polyurethane, epoxy, rubberized asphalt, or a mixture thereof. Unlike the 
uppermost adhesive layer 16, shown in FIG. 1, however, this intermediate 
adhesive layer 34, also shown in FIG. 1, is applied to all of the 
aggregate, coarse aggregate and fine aggregate, in the next downward 
layer, the support layer 20. This intermediate layer 34 also stabilizes 
the underlying aggregate in the support layer 20 and is substantially 
impervious to moisture and free of voids. This moisture barrier 32 
functions as a barrier to moisture between the base 21 and the reservoir 
layer 14. This moisture barrier 36 in the FIG. 2 configuration is optional 
and may be eliminated to simplify construction. 
Like the reservoir layer 14, the support layer 20 also preferably comprises 
coarse aggregate 42 and fine aggregate 40, and also supports the overlying 
layers. Unlike the reservoir layer 14, however, the support layer 20 is 
dry throughout because of the moisture barrier 32. The dry fine aggregate 
40 stabilizes the coarse aggregate 42. The preferred fine aggregate 40 may 
be sand, although other fine aggregate materials may be utilized in 
accordance with the invention, such as disclosed in prior application, 
U.S. Pat. No. 4,881,846, entitled BUILT-UP PLAYING COURT STRUCTURE AND 
METHOD FOR ITS CONSTRUCTION, filed Mar. 28, 1988, and co-pending 
application filed concurrently herewith, entitled IMPROVED MOISTURE 
RETAINING TOP SURFACE FOR A BUILT-UP GRANULAR STRUCTURE AND METHOD FOR ITS 
CONSTRUCTION. Likewise, the preferred coarse aggregate 42 is gravel or 
pebbles, but other coarse aggregate materials may be utilized in 
accordance with the invention, such as disclosed in those applications 
mentioned above. The coarse aggregate 42 is preferably three-quarter inch 
to one inch in diameter. This support layer 20 rests directly upon the 
base 21 which may be an existing structure, soil, or any other firm, 
preferably (but not necessarily) level surface. While desirably so, base 
21 need not be level inasmuch as support layer 20 will compensate for any 
unevenness therein. No sealant or impermeable layer is required between 
this base 21 and the support layer 20, such as is disclosed in prior 
application Ser. No. 07/174,118, entitled BUILT-UP PLAYING COURT STRUCTURE 
AND METHOD FOR ITS CONSTRUCTION, filed Mar. 28, 1988, and co-pending 
application filed concurrently herewith, entitled IMPROVED MOISTURE 
RETAINING TOP SURFACE FOR A BUILT-UP GRANULAR STRUCTURE, AND METHOD FOR 
ITS CONSTRUCTION, since this function is performed by support layer 20 and 
moisture barrier 32. 
In an alternative embodiment, not shown, a permeable layer could replace 
the moisture barrier 32 shown in FIGS. 1 and 2. In such an embodiment, an 
alternative moisture barrier would need to be disposed beneath the 
aggregate, such as atop the base 21, as disclosed in prior application, 
U.S. Pat. No. 4,881,846, entitled BUILT-UP PLAYING COURT STRUCTURE AND 
METHOD FOR ITS CONSTRUCTION, filed Mar. 28, 1988. This embodiment is 
useful when a thicker aggregate bed is needed for drainage. The preferred 
additional permeable layer is an adhesive elastomer layer, such as 
discussed above, to allow fluid conductivity between beds, yet stabilize 
the coarse aggregate. 
The thickness of the layers or beds and the coarseness of the aggregate can 
be varied, depending on moisturization and stability factors. The 
invention is not limited to the particular beds represented in the 
drawings. 
Containment walls 44 are disposed about the periphery of the layered 
structure, preferably four inches to six inches high, but they could be of 
any desired height. Also placed in the containment are drainage outlets 46 
to directly remove fluid surplus at the upper layer 12. These drainage 
outlets 46 can also be used as inlets to introduce water to the structure 
by flooding the upper layer 12. As many outlets/inlets 46 as deemed 
necessary are provided; they may be screened 24 to prevent aggregate from 
entering. Such screens 24 should be of finer mesh than the finest 
aggregate of the upper layer 12. 
Moisturization of the structure 10 can be accomplished by utilizing natural 
rain in combination with the reservoir layer 14. The reservoir layer 14 
becomes saturated with the water for use in moisturizing the upper layer 
12 by wicking action, over an extended period, such as a day or more. 
Excess water is drained through the outlets 46. In dry climates or 
periods, watering or moisturization can be achieved by sprinkling, either 
manual or automatic, of the upper layer 12, by flooding the upper layer 12 
through the conduit outlets 46 (which also serve as inlets), by sunken 
hoses in the upper layer 12 (particularly useful in windy conditions), or 
other means, common to the art, for providing moisturization to surfaces. 
As discussed in prior application, U.S. Pat. No 4,881,846, entitled 
BUILT-UP PLAYING COURT STRUCTURE AND METHOD FOR ITS CONSTRUCTION, filed 
Mar. 28, 1988, other fluids, such as weed killer and antifreeze, can be 
utilized to not only moisturize the surface, but provide other functions. 
The invention further comprises a method for constructing a built-up, 
moisture content controlling granular structure comprising the steps of 
obtaining a foundation for the granular structure; providing a moisture 
barrier above the foundation; providing a containment wall peripherally 
about the foundation; providing a subsurface reservoir bed above the 
moisture barrier; providing an upper surface layer comprising fine 
aggregate atop the subsurface reservoir bed; and providing means for 
stabilizing the subsurface reservoir bed and for providing adequate fluid 
conductivity between the subsurface reservoir bed and the upper surface 
layer to substantially maintain the selected moisture content in the upper 
surface layer. Maintenance of the upper layer 12 is accomplished by wide 
drag brooming or other means, common to the art, for maintaining granular 
surfaces. 
Although the invention has been described with reference to these preferred 
embodiments, other embodiments can achieve the same results. Variations 
and modifications of the present invention will be obvious to those 
skilled in the art and it is intended to cover in the appended claims all 
such modifications and equivalents.