Last updated: January 12, 2024
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Podcast 053: National Mall Plan Project Part 2 - Turf Project
National Park Service
National Mall Turf Project
Paul Cady: Ok Sean, can you describe the Mall turf project as it has been implemented?
Sean Kennealy: Well, the Mall turf project was to restore the turf and soil systems on the National Mall between 3rd and 14th street. The project included the installation of new underground cisterns to collect water runoff, and rain, and stormwater. We installed new irrigation systems, we installed new drainage systems, new soils, and new turf, as well as installed a granite curb edge around the turf panels that prevented the migration of the existing gravel walkways (the gravel itself) from migrating into the turf.
Paul Cady: What is the time frame for this project, and where are you in the implementation process?
Sean Kennealy: Well the project is actually three phases: we just completed the first of the three phases which was the section of green space between 3rd and 7th street and included three large center panels of the Mall. The second phase includes the center panels between 7th and 10th street, and then the last phase is the area between 10th street and 14th street.
Paul Cady: Is the work being implemented by the NPS or outside contractors?
Sean Kennealy: The work is being awarded by the National Park Service and we are hiring contractors, private contractors, to perform the work.
Enhanced Soil
Paul Cady: Can you go into more detail about the enhanced soil you’re using to alleviate the compaction on the Mall?
Sean Kennealy: The soil that we’re using out there is an engineered soil that has a very high sand content to allow for drainage of the water very quickly so that we don’t have standing water out there. Then we can actually get the water back into our cistern systems a little more quickly. It also has a higher organic compound rate where we have a good mix of the sand and organics into our soil mixture.
Paul Cady: What kind of grass are you using?
Sean Kennealy: We’re using a turf type tall fescue with a blend of bluegrass.
Paul Cady: How did you chose that particular [grass]?
Sean Kennealy: Well what we did was we researched a lot with regard to other types of turf fields, particularly fields that received a lot of high use and high impact. We looked at baseball stadiums, football stadiums, and other types of venues that have a real high use and high impact events on them. We decided that the turf type tall fescue with a 10% bluegrass blend was the best mixture for the amount of use that the Mall gets.
Irrigation
Paul Cady: How does the irrigation set up? Where’s the water coming from?
Sean Kennealy: So the irrigation is a very robust underground irrigation system, it’s not your conventional (or residential) pop up head type system. We had a system like that previously that was just compromised too much with tent stakes and other types of high impact events on the Mall. What we did was we installed a very robust irrigation system it still, it does, have pop up heads but they are few and far between. They shoot the water out at very high rates, or flows, and pressures so that we can cover the center panels with the minimal amount of heads. We also installed the irrigation lines 4 feet deep, because one of the things that was changed in our permanent process is that no one can run a stake larger, or drive a stake larger, than 36 inches into the ground. We’ve lowered all the piping to 4ft; we’ve put all the heads on the exterior, or the perimeter, of the panel so that we have clearly identified ‘no stake areas’ on the National Mall.
Paul Cady: How does the irrigation connect to the cistern system?
Sean Kennealy: So what happens is, we have a number of drains around the perimeter of the center panels of the National Mall. The drains are collected through a series of piping, the piping then dumps the rainwater into our cisterns. When we are completed with the project, the total amount of storm water capacity will be 1,000,000 gallons. So we have four 250,000 gallon underground cisterns that will collect all the rainwater from the runoff from the center panels of the Mall. Through piping into these 250,000 gallon cisterns, from there we have various pumps that will transfer that water to our irrigation pump. When the water gets to that point the water will be filtered through a ultraviolet light filter system and then it will be pumped out into the irrigation system where eventually it will go to the heads and be sprinkled on the ground.
Paul Cady: Has the paving system been looked at on the Mall?
Paving System
Sean Kennealy: We’ve looked at the paving system, we’ve looked at it very extensively. We continue to look at that. We do have some significant issues with the gravel walkways, however it’s something that we’re going to continue to work with the commissions (or review commissions or review boards) to look at what the best, or most appropriate, paving material is on the National Mall.
Paul Cady: Were aspects of the project excluded that you would have liked to have seen included?
Sean Kennealy: No, the first phase included a lot of the infrastructure that was necessary for the new soil and turf systems to thrive. We actually installed a lot of infrastructure to accommodate phases 2 and 3 in the first phase so phase 1 was a success. We are just getting ready for phase 2 and phase 3 as funding becomes available.
Paul Cady: Do have any suggestions for institutions looking to do a similar kind of project?
Sean Kennealy: Sure, I think that you really need to take a take a look at your soil mix and see what type of soils and turf is most appropriate for the application. I think that by doing a lot of research upfront, depending on how your areas are used, you can really drive what types of turf (turf systems) you use, as well as your soils.
Paul Cady: Is there anything additional you’d like to add about the implementation of this project?
Sean Kennealy: I think that it’s been a great project for the United States. I know our visitors have really enjoyed coming out to the Mall and seeing the true difference between what an investment we made is, compared to what we’ve been doing in the past. When you look at the newly renovated center panels it’s a big difference between what our investment has gotten us, compared to where we were years ago on the other areas, so it’s making a huge difference.
Paul Cady: Is this going to be a model for future projects the National Park Service is going to be doing?
Sean Kennealy: We hope so, we hope so. I think what we’ve learned from this, in terms of how to collect water, and to recycle water, how to design, install robust irrigation systems, and how to manage our turf is something we’re going to use as a model throughout the park. Another thing that we learned is that hiring appropriate staff is really key to the success of a turf system. The National Park Service hired the first ever turf manager in the Park Service, and certainly here on the National Mall it was something that we’d been looking into. We went ahead and made the investment in a high caliper type of a person, with a turf management degree, who was well versed in turf management and soil science. It was a great investment that we made in our hiring to actually hire a turf manager.
Paul Cady: Alright, well thanks very much Sean for talking to me today, I really appreciate [it].
Sean Kennealy: Hey, no problem Paul. I hope this helps, and good luck in all your future endeavors.
Paul Cady: Thank you very much.
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