Wetlands Page 2

Wetlands Group
Problem 2: Dysfunctional Drains
Even with measures that improve the flow of stormwater to area storm drains, many cannot move the water out of the area. In some locations, sheet flow runs into other, unintended, areas of campus.

With the large number of trees on campus, leaf litter is a major hindrance to the effectiveness of the current storm drain system. (See Appendix B for more examples of drains affected by leaf litter.)

Figure 3. A storm drain inlet (marked by a stake) is completely covered by leaves near O'Connor House.
Ron Smith, Grounds Superintendent, estimates that Rice spends as much as $4500 a year in cleaning catch basins and drain inlets, an arduous task performed by groundskeepers who struggle to keep them clear (personal communication).
Mark Wells, Maintenance Planner/Coordinator, suggests that cleaning out storm sewer debris with a vacuum truck/water jet system costs an additional $25,000 yearly (personal communication).
Because of land subsidence and/or poor installation, some drains are actually higher than the surrounding area.

Figure 4. This storm drain inlet by Herring Hall is slightly raised over the surrounding ground, preventing the water from draining.
Lastly, some storm sewer inlets are too small or not the appropriate type of drain to effectively take in a large amount of sheet flow during a moderate to heavy rain event. Even though the storm sewer lines beneath them may be adequately sized, they are ineffective if water cannot get into them. According to a study performed by WPMA, some inlets are serviced by large storm lines which could be more fully utilized with a larger inlet (WPMA 1997). (See Appendix B for examples of these types of inlets).

The expenses and effort that are currently allocated to cleaning and maintaining the storm sewer system
Aesthetics of the campus
Environmental "friendliness"

Leaf litter can be kept out of drains by surrounding them with rings of monkey grass, a plant that is inexpensive and easy to maintain.

Figure 5. Monkey grass decreases the amount of leaf litter entering a storm drain inlet near the RMC.
Although one ring of monkey grass normally surrounds some storm drain inlets, they should be installed on every drain, where possible. We also recommend that two rings be planted, to filter out more debris.
Inlets with catch basins that can be easily removed and cleaned should also be investigated.
Where drain inlets are too high , they should be lowered.
Where inlets are ineffective, they should be increased in size or replaced with a more appropriate type of drain inlet.