A pro’s take on this precise project

With the onset of baseball right around the corner, much of the late fall and winter weather has prevented programs from finishing their fields for the upcoming season. Additionally, the synthetic turf industry has entered the ball field business riding a major wave. Gone are the dirt cutouts at each base, with newer infill systems allowing the players to safely slide on the rubber and sand-base fibers. The home plate circle is being converted to turf as well, and several styles of mounds – both permanent and portable – are being installed, as well.


Mike Hebrard on his modified Smithco Super Star, which he had modified to laser grade.

This comes, however, with a hefty price tag. A synthetic mound can go for $2,500 to $10,000, which isn’t always in a facility’s budget.

Many baseball traditionalists insist on a clay mound, and there are many options to install one. Having done a number of mound renovations and complete builds on new grass infields I’ve learned that constructing a clay mound on a synthetic surface can easily be accomplished. Following are step-by-step procedures to help you tackle this task.


A mound frame built by the author. It is 4 inches high and the rubber is 6 inches high, equaling 10 inches, the proper height of the rubber from the top of home plate. There was a 1-foot drop to second base, meaning the mound area was 6 inches below home plate. The frame was raised 6 inches in order to get the correct height and slope.

First, attach a string from the apex of home plate to the middle of the base anchor at second base. You should also attach a tape measure through the pin at home before threading in the string. This allows you to check for distance several times without interfering with the centerline string.

Using a laser will allow you to quickly check the elevation of home plate and to ensure a height of 10 inches at the top of the rubber. Check the elevation to second base first to see what adjustments might need to be made at the mound location if the grade is too steep. On the mound I built, the drop to second base was a full foot, making the mound area approximately 6 inches too low. This elevation needed to be adjusted to ensure the rubber ended up 10 inches above home plate for a consistent slope.


Loading the clay into the back table of the mound.

Since the clay mound is meant to be permanent, I made a 4-inch-high angle iron frame that the rubber fits into. I then mark a perpendicular line in the middle of the rubber. Snap the string several times to ensure the rubber is aligned properly, check with the tape for the 60-foot-6-inch distance and check with a level, as well. The measurement is from the apex of home plate to the front edge of the rubber. The fixed frame allows for ease in rotation or replacement and keeps the measuring and leveling to a minimum. I built a gravel base and spiked the frame at the proper elevation. Add some clay around the rubber and pack it so it doesn’t move. Another procedure I learned was to make a wood frame from 2x10s into a 4-by-6-foot box. I bracketed two opposite ends and hinged the other corners. Placing the front edge of the frame in front of the rubber about 8 inches, level the box to the same elevation as the rubber. Gradually fill and pack the inside of the frame until the clay is level with the top. I made a 5-foot-long board with a handle to constantly smooth and level the clay. Once the clay is firmly packed, finish off the compaction by using an old tarp and a mechanical plate compactor. Once the back table is compacted, remove the frame and tamp the edges so they won’t collapse. If you already have an established mound and want to build up the back table you can use a 2×4 and add clay to the bottom of the frame to get the same results.


Mike Hebrard made this mound gauge to properly set the slope for the mound, it can do 180 degrees.
PHOTOS COURTESY OF MIKE HEBRARD UNLESS OTHERWISE NOTED.

Grass Line and Infield Grading

Another preparation before the season starts is to laser-grade the skin area. Unfortunately, not everyone has the resources to have it done. Before laser grading it is important to rough up the existing dirt so that newly added material will blend in. It is a good idea to knock the grass edges (lips on most fields) down so that less dirt is needed. This can be done by picking under the grass edges and pulling the dirt out, raking the loose material out, and then tamping down the high grass lip. You can gain a little dirt and lower the grass line. The process is much easier during the wet months. If properly done, you can knock down the edge as much as an inch and move it closer toward the skin. Digging a deep, narrow trench along the grass edge and tamping it down is another way to remedy the problem. If you have a large lip and a large puddle of water that is going nowhere, you might try my quick method to remove the water without walking in the puddle. For best results do this early in the day. Use a square point shovel and cut a slit in the turf as deep as you can perpendicular to the edge. Gradually lift the sod up and continue making the slit back. The water will start draining under the turf and eventually run out to a lower area. Gradually pull the soil from under the turf and toss it back onto the low area of the skin portion of the infield. You might have to dig a lower area out near the slit. Every once in awhile repeat the process from the start and lift the sod higher each time. You will actually hear the sound of slurping water passing along the channel. If you do that early in the day, the puddle size will dramatically reduce in size. Right before the game, simply step on the slit, making it a bit lower and ready for play. The normal fix I see is that the sod is cut out with a shovel and left on the turf. This tends to be unsightly as well as unsafe.

As for grading, if you have access to laser equipment there are a couple of options to the setting of the grades and location of the laser. Most lasers have a dual slope capability, meaning that you can have one slope go down from home plate to second base and the other 90 degrees going from third to first base. Another is a cone grade, which allows you to uniformly grade at a .5 percent grade to 1.5 percent in all directions. I usually set my tripod for the laser with two legs on the back part of the rubber and the third toward second base. This allows the setting to be in the home plate to second base axis and pretty close to the first to third base axis. Since most of the game is played on the infield, I try to make all the bases and home plate close to the same elevation with a little drop to second. If you have an infield tarp, this will help direct the rainwater off the tarp.

I own a laser that can do both a dual slope and a cone, which comes in handy for matching an inadequately designed field where there might be a big grade difference between the bases. Depending on soil structure, the infield can be graded flat to 1 percent fall from the mound. Any more slope than that it might affect the flight of the ball, since the throws are usually shorter and need to be more accurate. The higher the level and with well-draining soil, a flatter grade can be done.

If you don’t have access to a cone-style laser, you can set the dual slope to the desired fall and rotate to each quadrant. This can be cumbersome. If your grade goes up from the infield grass edge to the back of the infield grass a cone won’t be recommended as this won’t blend effectively.

If you’re doing the outfield or a large area, the middle of center field might be the best location. There are a couple of options there, too. You can grade from the back arc of the infield with a cone, drop it all the way to the outfield fence, grade it from the center field to both foul lines or a combination of both. The main objective is to run the water off the skin portion of the infield before it has a chance to absorb into the dirt.

Another procedure I came up with is my new AFD Mound Gauge. Since most of the ones made are designed to only check the front slope, I made mine so it will do a 180-degree angle from the recommended slope. Measuring out 18 inches in front of the rubber and 1 inch below the rubber, I pound in a .5-inch metal conduit. From that point mark a 9-foot-radius circle around the mound to indicate where to stop the clay mound. At this point I pin in my mound gauge and set the gauge level with the adjustable leg (a wheel is also an option). Setting the mound gauge near the side, gradually add clay along the gradient indicators, rake and tamp to match the slope. This will need to be repeated several times to get the proper compaction.


A frame made to build the back table of the mound.

Follow the same procedure on the front part of the slope, but allow for the final grade to be about 2.5 inches lower to allow for the clay mound blocks to be installed if desired. Once the entire mound front has been added with clay and mound blocks, remove the gauge and finish tamping or plate packing. The back edge of the table will be filled in and tamped to the 9-foot-radius arc so there is no daylight between the slope and the turf.


Adding a calcined topdressing allows for moisture control of the mound clay and prevents it from being sticky during use.
PHOTO COURTESY OF CLAYTON CREECH NEWPORT SPORTS HISTORIAN.

For added wear tolerance the mound blocks can be placed on their edge to add more stability to the bases. Once the front of the mound has been graded and properly packed use a ground rake to scar the blocks, wet down lightly, add bagged mound clay and tamp. Reinstall the mound gauge and check for high/low spots. For the high spots move the gauge back and forth to scar the clay, and then use a Hula Hoe to shave the high spots. The low spots might need to be wet down a bit and more bag clay added and tamped. Once the final shape has been completed, add a topdressing such as calcined clay, two to three 50-pound bags is usually enough. Broom to a smooth finish and wet down.


Mound blocks are set just below grade to allow for mound clay finish the bond.
PHOTO COURTESY OF CLAYTON CREECH NEWPORT SPORTS HISTORIAN.

I like using a contrasting color such as Turface Pro League to highlight the mound. When wet, the Pro League Red calcined clay comes real close to matching the color of the skin portion of the synthetic turf. If possible, soak heavily, let dry and cover. Whether it is 100 degrees and sunny or cold with a pouring rain the mound should be covered all the time except when there is play. Hot sun will crack the clay, and heavy rain will erode the clay into the turf and make the mound unplayable.


A mound done recently by the author.

Since this was a newly installed field we protected the synthetic turf with 4-by-8-foot sheets of .75-inch plywood for the front-end tractor to drive on. I had four mounds to do before the end of the year and, with improvement and strategies each time, we went from 7 hours to eventually 4 hours from start to completion.


Final mound build took three and a half hours.

Mike Hebrard is owner/operator of Athletic Field Design, based in Clackamas, Ore. He’s a frequent speaker at national and regional conferences.