Expansive soils or plastic soils and use of base course materials consisting of these types of soils can create further problems.

Frost action is exaggerated where frost susceptible materials exist with moisture available to generate frost heave.

It is, therefore, necessary for the owner, or the contractor, or a consultant retained by either the owner or the contractor, to identify soil conditions existing at the site and to take these conditions into account in designing the court or track. Site preparation, including stripping, placement of backfill and base construction must be properly performed to minimize the risk of problems due to subsoil and subgrade conditions. (See Site Preparation Guidelines, Section 1.C.)

Obviously, the more serious conditions that require an adequate study include:

1.         The existence of peat or other organic soils at the site;
2.         Uncontrolled fill materials or waste materials at the site;
3.         Expansive soils at the site;
4.         High ground water conditions or surface water retention areas (low area flooding);
5.         Special usage of the facility (i.e. using tennis court as ice skating rink).

These risks have been identified in subsequent paragraphs, with Guidelines for investigation under different circumstances. Such risks require the owner and the contractor to make a joint decision as to which level of investigation to make before the project is constructed. This is done so that an adequate study can be made, and in the event of any problems developing because of subgrade conditions, the responsibility can be clearly allocated between the owner and the contractor.

It should be noted that if test pits are dug, the backfill must be adequately compacted or the test pit itself will become a source of depression in the surface. Thus, such test pits should be located between courts or outside the limits of the tennis or track surface to be constructed.

Soils should be classified, in general, in accordance with the visual manual method of identification of soils, utilizing the Unified Soil Classification System (ASTM Methods D 2488 “Description of Soil Visual Manual Procedure”, and D 2487 “Classification of Soils for Engineering Purposes”). It is not intended, however, that a rigorous use of these methods be required, but only use of terminology that will describe the soil conditions in terms of soil types using the Unified Soil Classification symbols, such as CL, CH, etc.

Data obtained from this investigation should be prepared for later reference, if necessary, or for review by a qualified engineer if an evaluation is decided upon by the owner and/or the contractor.

ASTM Method D 1452 is recommended for performing these borings, which should be carried to a depth of 5 ft. minimum, or to firm materials, if unsuitable materials are encountered. These borings may be made by the owner or contractor, or by a qualified engineer or architect.

If borings are made by the owner or contractor, soils should be reclassified, again in accordance with D 2488 and D 2487, by a geotechnical engineer selected or approved by the owner. In addition, a letter report commenting on soil conditions and recommending design and construction procedures should be prepared by the geotechnical engineer or architect.

This information should be prepared on boring log forms that are utilized by the geotechnical consultant, and accompanied by a report summarizing conditions encountered, the test data, and recommendations for site preparation and design of the court or track, including compaction specifications for the backfill material.

Where expansive soils are indicated, whether due to natural or fill materials, appropriate expansion tests should be performed to determine the degree of expansion that can be expected.

The geotechnical consultant should provide recommendations for drainage and any other recommendations considered appropriate to minimize the risk of ultimate damage to the surface due to settlement or heave, or due to instability during construction under the weight of the construction equipment.