Sport field trench drain applications are often simple and straight forward. There are four very common applications for trench drains in sporting areas. The first is channel drain around the inside of a track to ensure that no water stands next to the track surface. Standing water near the track surface causes a delamination of the costly track surface. The second most common application for a trench drain is along one edge of a court to allow for a simple grading of the court. This is common on basketball and tennis courts to ensure a level court and no ponding on the playing surface. The third most common application for trench drain is behind the back stop at baseball and softball fields. A trench drain allows the playing field to have a simple grade and keeps the playing field dry during rain events. The fourth common application for trench drains is in the stadium and bleacher area. A trench drain at the bottom of the bleachers keeps the water from running down into the sporting area while keeping pedestrian areas flat and level.  This is often seen in football, soccer, lacrosse, and field hockey stadiums.

Design Considerations

Sizing the drain

• For trench drains around a track, the trench drain is mainly there to protect the track surface and protect that investment.  The trench drain takes any rain water off the track and moves it to the underground piping system.  There are no safety issues with standing water so if the system backs up temporarily during a large rain event there are no problems associated with that.  These types of trench drain systems are typically 4" wide and often times do not have a built in slope.
• In sheet flow applications, such as at the bottom of bleachers, you may need to size the drain based on it's grate inlet capacity. Sometimes, especially with heel proof grates, the inlet capacity may determine the channel size. For ADA and Heel proof grates check to see that the inlet capacity of the grate is greater than what is required. If not, you may need to up size the channel to allow for proper capture through the grate.  Most bleacher applications are 4" to 8" trench drains.
• Be sure that you add the site slope when calculating the size of the drain (if there is any). The site slope will assist the trench increasing flow rates.
• These exterior applications will be handling storm water and you should use the minimum size that you calculate using the cubic feet per second storm water calculations. Often engineers want to oversize the drain to be conservative or design for a very large storm. This is not a good practice when it comes to trench drains. By doing this you not only add cost, but you keep flow rates inside the trench drain low which allows debris to build up. A radius bottom trench drain will help with debris buildup but it is best to design near actual capacity when possible.
• Be sure that the outlet capacity does not limit the flow of the drain. Outlet connections can be piped to structures or the trench can run directly into a structure. If piping to a structure make sure the pipe is sufficiently large (the pipe should typically be at least one size larger than the trench).

Choosing the channel

• Loading is typically not a big concern in sporting applications. The traffic on the trench is minimal and is usually limited to pedestrian traffic and landscaping equipment. Typically frames are not required in these applications. Light duty channels can be utilized for these applications.
• In exterior applications you need to ensure that the drain will not degrade with exposure to ultraviolet light (UV light).
• It is a good idea to use a trench channel that has a radius bottom. The radius bottom will help with the accumulation of debris.
• Sealing channel joints is typically not necessary.
• Exterior applications are not temperature controlled and will see severe changes in temperature. The drain should have similar thermal coefficients of expansion to that of the surrounding concrete encasement. For more information see material properties.

Selecting the grate

• Grates for sports field applications are typically only designed to handle pedestrian traffic and some landscape maintenance equipment. Pedestrian or landscape areas can be almost any material, even plastic, as long as it is able to handle the ultraviolet light without degradation.
• If a grating must receive both vehicular traffic and pedestrian traffic look for grates that are both ADA compliant and rated for vehicular traffic. After these considerations are met the next most important thing is the amount of open area in the grate. It will want to plug up with smaller holes so the more open area you have the more likely the system is to function properly over the life of the facility.
• It is important to consider the amount of debris that is often present in near sports fields. The more open area and the larger the geometry of the openings the less likely the grate is to plug and not work properly.
• Be ware that certain metal grates can be attacked by fertilizers that may be used on natural grass fields.  For natural grass fields choose plastic or iron grates.
• Be sure the grates are properly anchored. This will prevent loss and damage to grates not properly seated in the trench body.

Designing the layout

• A sloping system is desirable when possible.  The sloping trench drain will move debris through the system and reduce maintenance.  If a sloping system is used, outlet pipes should be spaced regularly to minimize trench depth.  Excessive depth adds to installed costs of the trench drain system.
• To minimize the depth of the systems consider using non-sloping channels. Often times the flow rates are small and the added cost of a sloping system is not necessary.
• It is best to try and keep the trench drains out of direct pedestrian traffic when there will be large amounts of debris. Sometimes this is not possible so look for systems with maximum open area while still meeting the traffic requirements.
• The depth of the system that you are going to use can conflict with piping and other buried utilities.
• Outlets should be placed to minimize piping.  Using more outlets will keep the system depth shallow and keep the cost down.