Construction Services

Soccer, Lacrosse, Field Hockey Construction

Home » Field Construction » Baseball & Softball Field Design

Baseball Field

Softball & Baseball Field Design

In designing and laying out a baseball or softball diamond, it's important to proceed according to this sequence:

Survey the outer boundaries of the field, making sure there is sufficient room for foul territory;
Lay out home plate and then the bases and the pitcher's mound;
set out the skinned areas of the infield; then
The grass area of the infield, and
The outfield and foul territory

11.2a Survey and Layout
One of the most common errors made in the construction of sports facilities is the simple failure to survey. Professionals engaged in this field will frequently be called upon to "fix" fields which were constructed without the benefit of surveying, either because planners just thought it looked level or, as sometimes happened, because the field started out as a mowed area used for practice or informal plan and then evolved into a more widely used facility.

Table 11.1. Space Requirements

Whatever the reason, it is vitally important that any new construction or reconstruction project begin with a thorough survey of the site. Intuition and the naked eye will not provide sufficient understanding of the topography of the area; only a careful survey will accomplish that end.

Survey enough land to show how water moves through and around the area, and especially to show how it will move off the playing area. In many cases, it's necessary to survey about twice the area of the field itself.

Although many fields are simply oriented to the available space, official rule books for baseball suggest that a line drawn from the tip of home plate through the pitcher's mound and second base should point in an east-northeast direction. Such an orientation prevents the batter and catcher from looking into the sun as they stand at the plate, and positions most of the fielders in such a way that their eye-line to the batter is not directly into the setting sun.

In laying out the field, it is important to reserve space for dugouts, backstop, surrounding fence, and other peripheral elements. All too often, a failure to plan for these structures forces the builders to install them in an awkward and unsuitable fashion, which may compromise player safety and disturb a well-planned drainage scheme.

Table 11.1 suggests minimum space requirements for baseball and softball fields, with sufficient space around the playing field for fence lines, dugouts, spectator seating, and swales.

The chart in Table 11.2 displays the square footage of the skinned area and the grass area for common size baseball and softball fields, including foul territory.

11.2b Design Criteria for New Construction

The highest point on the field is the pitcher's mound, and the field slopes away from the mound in all directions. The height of the pitching plate, or "rubber," is specified by the sanctioning body for each level of competition.

The infield should be higher than the rest of the field. To keep the infield playable, it's important that no water passes into the infield from the outfield or the sideline areas.

Although installed drain systems can be used successfully in some areas of the baseball diamond, these systems typically work poorly in the sand/clay soil of the skinned area. Under normal circumstances, water does not pass satisfactorily through the soil and into the drain structures. Therefore, proper positive surface drainage is the only way to prevent standing water on the skinned part of the infield.

Table 11.2. Square Footage of Skinned Area and Grass Area

The base lines should be carefully laid out to be as level as possible.

All slopes should have a continuous even grade from contour line to contour line at about ½% for the infield and 1 to 1½% for the outfield. This degree of slope will allow for runoff of water from the playing area to catch basins or swales outside the boundary lines or to lower contours.

Safety Issues

In designing the diamond, a number of important safety issues must be considered. One of the most obvious is the distance from the foul lines to the dugouts, grandstands, or other fixed objects. As a general rule, a minimum clearance of 25 ft. is required for Little League and softball fields, with twice as much for high school baseball and above. Because players must run through this area looking upward to track foul balls, the greatest possible clear area should be allowed (see Tables 11.8 and 11.9 for recommended clearance for each level of baseball and softball).

If possible, catch basins should be located outside the fences surrounding the playing area to prevent player injury. If the presence of grandstands requires the installation of catch basins inside the fences, they should be placed as close as possible to the fence or grandstand. In these circumstances, a small grid should be used to minimize the risk of injury.

In general, there should be no obstructions in the field of play (including foul territory). The rule books for each governing authority include requirements and other guidance related to that level of play. In designing a competitive baseball field (or, for that matter, any athletic field), it's always wise to have a copy of the rule book for the organization that governs that level of play. A list of addresses for governing bodies is included at the end of this chapter.

Figure 11.1.
The simplest and most common (good) field design--elevations noted in feet.

11.2c Field Designs with Preferred Contours

The following drawings illustrate three schemes for contouring the baseball field, including outside boundaries as well as infield and outfield. Note that (as we discussed above) the infield is higher than the outfield or the boundary areas.

In discussing these field contours, we will refer to three distinct areas of the baseball diamond. The Outfield is used here as commonly understood. The Skinned Area is the groomed dirt portion of the field where the infielders customarily stand during play. The Infield is the area enclosed by the base paths.

The Outfield

Figure 11.1 shows one of the simplest and most common field designs. The outfield slopes downward from the second and third base lines to the outfield fence at a rate of approximately 1%. The advantage of this design obviously lies in part in the simplicity of its contours and the ease of construction. The disadvantage is that the outfield fence is almost three feet lower than the base paths, which can give the field a rather disorienting look and feel (see Figure 11.4 for detailed skinned area and infield contours).

Grade stakes for this field can be set on a 50 foot grid pattern.

Figure 11.2. An improved (better) design, crowned from second base through the outfield--elevations noted in feet.

Figure 11.2 is an improved design, crowned from second base through center field to the outfield fence. The center crown directs water toward the boundaries and away from the center of the field. This design also provides a shorter path for runoff from the outfield--to the sidelines rather than all the way to the outfield fence. (The skinned area and infield detail for this design is provided in Figure 11.5)

When surveying this field design, set the stakes on the contour lines.

Figure 11.3 shows the authors' preferred design, which includes elements from each of the first two layouts. A crown has been developed from second base about one-third of the way to the outfield fence, allowing water to run off the heart of the field toward the foul lines. In the outer half of the outfield, runoff is toward the fence. Notice that fence lines are level around the entire field. (Skinned area and infield detail in Figure 11.5.)

When surveying this field design, grade stakes should be set on the contour lines.

The Skinned Area

In nearly every case, a field that is chronically unplayable is in that condition because of a poorly conceived skinned area design. Field planners typically fail to give this portion of the diamond the attention it deserves; remember that, at any given moment, all but three of the defensive players are standing on the skinned area.

Figure 11.3.
Authors' preferred (best) full-field design -- elevations noted in feet.

In laying out and surveying the skinned area, it's important to use more grade stakes than usual, due to the more gradual slope. A smaller error can have more troublesome consequences.

Figure 11.4 is a simple skinned area contour scheme (designed for use with the over-all field design in Figure 11.1), with a downward slope from the second and third base lines to the outfield. Although this is a relatively simple design to construct, and one which works adequately in medium to dry climates, it has the disadvantage that infield water must run off through the circled grass edge of the boundary between the skinned area and the outfield. Because loose soil from the skinned area tends to build up in that circled edge, a natural sill or "lip" can occur at that point, preventing proper drainage and holding the water in the skinned area.

Figure 11.5 shows a crowned skinned surface (for use with the field designs in Figures 11.2 and 11.3), which channels runoff to the foul lines, rather than toward the outfield. Because of this contour, water does not have to flow through the circled grass edge to leave the infield, making it a preferred design for moderate and rainy areas.

Figure 11.4. A simple (good) skinned area design--elevations noted in feet.

The Infield
The pitcher's mound is the highest point of the field, with the rest of the infield sloping away in all directions toward the base paths, as shown in figures 11.4 and 11.5.

Figure 11.6 is an alternative infield design which raises both the pitcher's mound and home plate by three inches. This change creates the illusion of a higher pitcher's mound, increasing the visual interest in the game for spectators and helping to keep the heart of the infield as dry as possible, but does not change the relative height of the pitcher and the batter. This design can be used to replace the grass infield design in Figure 11.4 or Figure 11.5 to create a field that is superior in both esthetics and performance. This design is also well suited to softball, since the pitcher's plate and home plate are level.

The Pitcher's Mound
The regulation pitcher's mound is a circle 18 feet in diameter, with a flattened top area that is 5 feet wide and 34 inches from front to back. This flattened area extends 6 inches in front of the pitcher's plate, or rubber, and is elevated 10 inches above home plate. Beginning at the front of the flattened area, the mound is to slope toward home plate at the rate of 1 inch per foot for the first 6 feet, then gradually slope the remaining 4 inches. The center of the mound is 59 feet from the white point of home plate, and 18 inches in front of the pitcher's plate. Figure 11.7 shows the appropriate contours for a pitcher's mound, and Figure 11.22 (in Section 11.3 on field construction) is a photograph showing a tool that can simplify the task of setting or resetting the correct contours.

11.2d Skinned Infields
Skinned infields (sometimes called "dirt infields") are those which have a continuous skinned playing surface all the way to the grass arc where the outfield begins. Skinned infields are recommended for softball fields, and are a requirement for some softball tournament play. Skinned infields could also work well for baseball fields, and may be preferred to grass infields, which require more maintenance and more frequent renovation. If the facility has a limited maintenance staff, the skinned infield is easier to keep playable, requiring less attention to matters such as lip buildup and removal.

Figure 11.6.
Alternative infield design with raised mound and home plate--elevations noted in feet. A skinned infield that has grass in foul territory has greater visual appeal than a skinned infield that has a dirt surface all the way to the dugouts. This is especially true of a completely skinned regulation (90 foot bases) baseball field, which has some 25,000 square feet of skinned surface, better than half an acre. Figure 11.8 shows an example of the typical skinned infield (without grass in foul territory), and an alternative and superior design with grass in foul territory, which allows for improved appearance and playability. The grading plan is the same as shown in Figures 11.4 and 11.5. For softball, use the infield grading plan shown in Figure 11.6 to keep the pitcher's plate level with home plate.

11.2e Multiple-Field Layouts
In recent years, the growing popularity of amateur sports leagues has led to the construction of hundreds of multiple-field complexes throughout North America. In designing this type of facility, several important factors should be kept in mind.

Figure 11.7.
The regulation pitcher's mound. The radius of a regulation pitcher's mound is 9 feet, with the center of the circle 18" in front of the front edge of the rubber.

Figure 11.8.
Skinned infields, typical design (left) and superior design (right).
Ideally, all fields in a complex should be oriented so that a line from home plate through the pitcher's mound is pointing east-northeast. This avoids the need for either the catcher or the batter to look directly into the sun during play. However, orienting all the fields in this manner isn't the most space-efficient way to design the complex.

A common multiple-field layout for younger children is to place four home plates at the corner of a square with the outfields from the four fields sharing space. Younger players (especially Pee-Wee and Little League minor leagues) seldom hit the ball far into the outfield, and the danger of contact among players from different games is minimal (see Figure 11.9).

Figure 11.9.
Multiple-field layout with home plates at four corners of square--elevations noted in feet.

Many complexes for older players are designed with home plates from four fields back-to-back (see Figure 11.10). This is a fairly efficient use of space, but can lead to a hazard when pop-ups in foul territory stray into another field. This design should be used only for experienced players, and as much space as possible should be left between the backstops. In addition, overhanging backstops should be used wherever possible, to prevent pop-ups from going backward onto the next field.

This back-to-back design is obviously a preferred method for players of Little League age and older, who need more clearance for safety's sake. However, it requires substantially more space to lay out four fields in this fashion; if the two layouts in Figures 11.9 and 11.10 show the same size fields, then the back-to-back layout would take up more space (almost twice as much).

In designing multiple-fields complexes, keep two other criteria in mind: each field should be designed to function as its own drainage system, with water draining away from the center of the complex, and within each field, the infield should not be lower than the outfield.

Figure 11.10.
Multiple-field layout with home plates together--elevations noted in feet.

11.2f Skinned Area Soil

Soil Selection
A critical factor in the competitiveness of any baseball diamond is the quality of the material used to surface the skinned area. We prefer a mixture of about 60% sand, 20% silt, and 20% clay. Covered diamonds typically use more silt--as much as 30%--and less sand. Higher-budget fields will typically add calcined clay or calcined diatomaceous earth to increase permeability.

All of the soil used in the skinned area should pass through a 3/8" wire screen. A minimum of 97% should pass through a number 8 sieve, and at least 60% should pass through a number 140 sieve.

Although particle size analysis is recommended before the installation of any skinned area soil, such analysis will not tell the planner how well the material will perform. It's a good idea to compare two or more different soils with similar particle sizes by doing some testing of material samples. There are several ways to do this.

One way is to punch four or five eighth-inch holes in the bottom of eight-ounce plastic cups, and then fill the cups ¾ full with samples of the soil being compared. Pour in water until it reaches the top of the cup. Allow the water to drain away, and see how long it takes the various samples to become firm enough to offer some resistance when a finger is pushed into the soil. The soil that firms up faster will return to playable condition faster. (Figure 11.11 illustrates this "cup test.")

A second test is to dump a bucket of each soil on the ground, then use a hose to soak it thoroughly. Then, as in the previous case, compare the time it takes each sample to firm up.

It's also a good idea to visit the stockyard before accepting material, and to look at undisturbed piles of the material to see the size of the gravel that is present in each. Choose the soil with the smallest gravel, preferably 1/8" or smaller. (The best time to visit the stockyard is shortly after a rain, which exposes the gravel.)

Pitcher's Mound and Batter's Box Soil
As any baseball or softball fan knows, the normal competitive stresses on the pitcher's mound typically leave that area riddled with pits and holes by the end of the game. Each pitcher scraps and kicks at the dirt to customize the surface to his or her liking, and this process goes on at least twice an inning throughout the game.

In order to construct a mound that will be fairly solid, and will stand up well both to the weather and to the continual excavation by pitchers, we recommend the use of clay-based soils for construction of the mound. Sand and silt-based soils tend to be easily disturbed by competitive stresses. Figure 11.12 shows the installation of a clay-based pitcher's mount material.

Skinned Area Conditioners and Drying Agents
One way to enhance the ability of the skinned area to withstand weather is through the use of conditioners designed for that purpose. Most of these products take one of two forms: calcined clay products and calcined diatomaceous earth products. Conditioners are tilled into the soil to soak up extra water during wet weather, and hold water in the soil during dry weather.

These conditioners can also be spread on wet portions of the skinned area to soak extra standing water. When used in this manner, these conditioners become "drying agents," drying out the field to allow play. There are also organic products, such as those manufactured from corncobs, which are specifically marketed as drying agents rather than conditioners. These organic products can soak up water to allow one game to be played, but should be removed before the next rain to prevent more serious problems, such as making the soil gummy and compacted. If these organic products are used as a conditioner (tilled into the soil and left), the affected portion of the skinned area may have to be completely excavated later to get rid of the gummy mess those corncob products can leave.

(To digress a moment on the subject of dealing with puddles: it's common to see people trying to get rid of puddles by sweeping the water out of them with a broom. This practice will certainly spread the water around and promote drying. However, unless the depression is then filled with additional soil, sweeping creates the potential for an even larger puddle the next time.)

Calcined clay and diatomaceous earth conditioners are also promoted as helping to fight compaction. Skinned areas with conditioners incorporated in the soil will loosen more easily and uniformly when a nail drag is used on the surface. Conditioners also let the skinned area support tractor weight faster than unconditioned skinned areas, so the maintenance staff can get out onto the field to drag it much faster after a rain.

One real benefit of calcined diatomaceous earth products is that they allow the maintenance staff to rake soil out of the edge of the grass, which is just about impossible with any other conditioner. As far as some fields managers are concerned, that quality alone makes these products worth the price, because it allows quick and easy removal of the grass-edge lip before it builds up.

Since these products absorb so much water, they also make the skinned area much less slippery. Of course, that's the main factor umpires use in deciding whether to call a game because of rain. If they see players slipping, they'll stop the game. So, one or twice a season, a conditioner should allow a field to support play when an unconditioned field would not. Of course, that also means it's a little safer for the players on the skinned area.

Skinned area conditioners also help with dust control during the summer, because they hold water in the soil longer. This is particularly true of the diatomaceous earth products; in most of the country, it should be possible to wet the soil thoroughly in the morning and play on it all day without having to stop and rewater. So for facilities that have games going on from morning until night, that can be a substantial benefit.

The diatomaceous earth conditioners can also be used in smaller volumes than calcined clay. Table 11.3 compares the volume and weight of various types of conditioners required for installation on a regulation baseball field to a depth of three inches.

Installing three and a half tons of diatomaceous earth conditioner, and tilling it in about three inches deep on an official size baseball field with a grass infield, takes about 40 man-hours from start to finish. Obviously, installation time is somewhat less for a smaller field, such as a Little League field.

Manufacturers' recommendations for the calcined clay products call for the skinned area soil to be mixed with 20 to 25% conditioner. Diatomaceous earth products require only a 10% mix, allowing a cost advantage. Figures 11.13 through 11.16 show the installation sequence for skinned area conditioners.

11.2g Turfgrass Selection
In selecting turfgrass for baseball fields, planners should consider the same general information on turf strengths and weaknesses outlined in Chapter 1. However, due to the character of the game of baseball, a smooth, fast infield which provides little resistance to the passage of grounders is usually considered ideal.

Warm season bermudagrass shows good overall tolerance to close cutting, making it ideal for baseball and softball installation, both in the South and in the transitional zone.

In cool season areas, however, turfgrass selection can be a little more complicated. In general, a highly effective method is to use a 5:50 mix of Kentucky bluegrass and perennial ryegrass , and some experts suggest using two varieties each of the Kentucky bluegrass and perennial ryegrass for genetic diversity and disease resistance.

To establish a turfgrass that will withstand cutting as short as 1", the planner may want to consider a mixture of perennial ryegrass and a Kentucky bluegrass cultivar chosen to tolerate close cutting. This mixture provides a good combination of aggressive growth habits and ability to tolerate low cutting heights preferred by coaches and players.

11.2h Installed Irrigation Systems
Since each baseball or softball field has its own dimensions, it's next to impossible to describe a "typical" irrigation plan for all fields. For instance, the distance from home plate to the outfield fence varies from field to field. The distance between the heads could vary from 47 feet to 67 feet, depending on the number of rows needed to reach the outfield fence from the infield arc, the water pressure at the field's edge, and the type of head used.

The distance between the heads could even be greater in foul territory around the infield. For example, if the width of the grass area from the base line to the dugout is 20 feet, the heads must be set no more than 20 feet apart. A field that has 50 feet of grass between the baseline and the dugout needs to have heads that are set 50 feet apart. Obviously, the type of head and the number of heads on a zone are important considerations.

The infield is the hardest area of the field on which to achieve good distribution uniformity. No matter where the heads are placed, some areas of the infield will receive more water than others, and supplemental hand-watering will be necessary. For this reason, the installation of a quick-coupler valve in the grass behind the pitcher's mound is recommended. The quick-coupler valve can also be used to hand-water the skinned area.

Figure 11.17 is an example of an installed irrigation system design for a baseball field that has 90 feet bases, a 355 feet distance to center field, and 60 feet between the baselines and the dugouts. This design requires water pressure of 75 PSI at field edge and yields a pressure of 60 PSI at the base of the sprinkler heads. Average precipitation rate for this system will be .35 inches/hour for full circle heads, .7 inches/hour for half-circle heads and .29 inches/hour for the infield. Run time for 1" watering will be 2 hours 51 minutes for full circle heads, 1 hour 26 minutes for half-circle heads, and 3 hours 28 minutes for the infield.

Figure 11.18 shows an installed irrigation system for a softball field or a Little League baseball field (with a skinned infield). Bases are 60 feet, center field is 215 feet, and the distance from home plate to the backstop is 25 feet. For a Little League field with a grass infield, install four sprinkler heads in the infield.

Figure 11.17.
Regulation baseball field irrigation system (90-foot bases).

Figure 11.18.
Softball field or Little league irrigation system (60-foot bases).

This design requires water pressure of 75 PSI at field edge and yields a pressure of 60 PSI at the base of the sprinkler heads. Average precipitation rate for this system will be .43 inches/hour for full circle heads, and .82 inches/hour for half-circle heads. Run time for 1" watering will be 2 hours 20 minutes for full circle heads, and 1 hour 13 minutes for half-circle heads.

11.2i Installed Drain Systems and Catch Basins

Installed Drain Systems
While the goal in designing a baseball diamond is to provide for positive surface drainage that will move water off the entire field without the need for installed drain systems, sometimes adequate surface drainage cannot be achieved. Under these circumstances, and where budgets allow, installed drain systems must be included. In nearly all cases, water can be moved off grass areas more quickly by internal drainage structures. (But remember that installed drain systems are not effective for skinned areas.)

Before installing drainage structures, it's vitally important to understand the local soil type and the direction of water movement on the field. In many cases, even where soils are heavy, drainage structures are installed parallel to the direction of water movement, with the goal of helping the water move in its natural direction.

However, as a wise farmer would point out, in heavy soils, good drainage structures are installed across the flow of water, rather than parallel to it. (In sandy soils, the planner has a good deal more flexibility in designing installed drain systems.) By laying out the drainage structure 45 to 90 degrees from the direction of movement, the planner allows the structure to intercept the water and channel it away from the area. This is especially true when installing strip drains, as discussed in Chapter 12 (12.2g). In planning installed drain systems, it's important to remember that the purpose of an installed drain system is to minimize the distance water must travel before it begins rapid removal from the playing surface.

So, before making a decision on the design or construction of an installed drain system, it's a good idea to try to observe the direction of water movement, either by going to the site during a rain, or performing a topographic survey. (See Chapter 8 for more information on the design and construction of installed drain systems.)

Figures 11.19 through 11.21 show installed drain system designs for use with field designs shown in this chapter. All of these designs could be constructed either with pipe drains or with strip drains. The advantage of these designs is the trench can be laid out at a consistent depth because they follow the contour, sloping downward toward the collector drain. Also, the field drains are installed at a 45 degree angle to the direction of the flow of the surface water. For strip drain systems, that means some of the runoff will be intercepted.

(The purpose of the drain lines in the skinned area is to provide a continuous flow of water from turf areas and does not mean positive surface drainage can be compromised in these areas. For completely skinned (dirt) infields, drain lines can be eliminated altogether, since they will have little or no effect on skinned area surface drainage.)

Catch Basins
Space limitations sometimes make it impossible to design sideline contours that are sufficient to shed the necessary amount of water from the playing surface. This problem is frequently caused by sideline grandstands or by hilly surrounding terrain. Under such circumstances, it may be necessary to install catch basins.

Figure 11.19.
Installed drain system for simple field design shown in Figure 11.1.
In planning for catch basins, select locations just outside fences, where they will be shielded from the playing area. Because of the disturbance to contours that grandstands can cause, placing the catch basin right in front of the stands can often help to drain swampy areas. (Catch basins also serve as junction boxes for installed drain systems.)

Figure 11.20.
Installed drain system for better field design shown in Figure 11.2.

Figure 11.21.
Installed drain system for authors' preferred field design.