where we play
USING WATER SENSITIVE DESIGN TO HIT CARBON EMISSIONS OUT OF THE GOLF COURSE
Linda Norman of ACH Consulting for the NZ Stormwater Conference 2023
The development and operation of golf courses results in a significant amount of CO2 emissions. Roughly 33% of the CO2 emissions results from the initial development of the course. The installation plus the materials for stormwater management and drainage on a golf course produces an average of 1,400 metric tonnes of CO2 (Saito, O, 2010), just over 10% of the total CO2 emissions from course development. Water sensitive design (WSD) can help offset and sequester CO2.
WSD is a large part of the Te Arai Links golf course infrastructure design and overall development. The stormwater management and drainage on Te Arai Links golf courses resulted in the installation of 5.4 ha of swales, raingardens and bioretention basins. Around 50% of drainage related CO2 emissions were reduced and offset through WSD.
A reduction of CO2 emissions was achieved by reducing the amount of concrete pipe installed underground and keeping the drainage on the surface. One meter of 225 mm diameter concrete drainage pipe results in 17.17 kg CO2 emissions for production and transport (Concrete Pipeline Systems Association, 2010). Using vegetated swales kept 15,000 lineal m of stormwater drainage above ground. The above ground drainage reduced the CO2 emissions by 250 metric tonnes. Further CO2 emissions reductions resulted from the vegetated swales requiring less hours of heavy earth moving equipment operation for installation. Unlike traditional drainage pipes, vegetated swales do not require trenches and deep excavations to be installed.
We know that vegetated swales, bioretention devices, and other green infrastructure remove metals and nutrients from stormwater runoff by mimicking natural systems. The same natural systems that remove contaminants are also efficient at sequestering carbon.
Grasses and reeds, common to vegetated swales and biotreatment systems continuously sequester carbon, offsetting CO2 emissions resulting from construction. Bioretention basins and swales sequester an average of 3.1 metric tonnes/ha/year of carbon (Kavehei, E. et al., 2019). The sequestered carbon is permanently stored below ground within the roots and rhizomes where microorganisms help lock the carbon into the soils. Over a 30-year period, the 5.4 ha of bioretention devices, swales and raingardens will sequester 502 metric tonnes of CO2.
As we were able to use the local sands overlain with coconut matting in the installation of the swales and biotreatment devices, the areas will not require excavation for maintenance or media replacement. As such, the CO2 will remain permanently sequestered. The use of coconut matting had the added benefit of reducing greenhouse gas emissions resulting from the use of synthetic landscaping fabrics.
The WSD can successfully reduce and offset CO2 emissions on a large project. The measurable reduction or offset was just over 1/3 of the CO2 emissions associated with golf course drainage. The WSD also reduced costs as pipes and pipe installation are more expensive than swales and biotreatment basins. As the green infrastructure has become part of the overall landscaping it adds to the amenity value of the overall project.
About the Author
Linda Norman joined ACH Consulting Ltd after immigrating to New Zealand in 2006. She trained in the US as an oceanographer and environmental engineer. Having achieved degrees in Chemistry and Geology as well as an advanced degree in oceanography and marine geophysics, she has worked for NASA, Woods Hole Oceanographic Institution, US Geological Survey and others. A Scientist and an Engineer, she brings her multidisciplinary experience to engineering design.