45
Table 6. Comparisons of Green and Grey Project Costs in Kansas City, MO 1
Watershed
Area
Grey Cost
Grey Cost/gallon
Grey + Green
OK Creek
4,770 acres (52% impervious)
$256 million
$5
$295 million ($230 million green)
Brush and
Town Fork Creeks
6,930 acres (45% impervious)
$439 million
$8.70
$552 million ($274 million green)
Middle Blue River
744 acres (34% impervious)
$51 million
$17
$35 million – all green
2 Source: Leeds (2008) 3
The degree to which green infrastructure’s benefits accrue depend in part on policy measures, particularly 4 the degree to which a property owner or developer gains credit for compliance with local ordinance 5 requirements. For the benefits cited in the scenario examples above, for example, savings occur when green 6 infrastructure measures are deemed to replace conventional detention or other storage. If, as is often the 7 case, local ordinances allow partial credit against detention, cost savings related to green infrastructure can 8 be limited or disappear, because the property owner must construct the conventional drainage structures 9 regardless. 10
Similarly, the degree to which private or public interests receive benefits can also affect green infrastructure 11 implementation. Adoption of green infrastructure features on private property, as envisioned in the Kansas 12 City plan, will benefit public infrastructure performance. When policies, such as stormwater utility/service 13 fee or tax credits are in place, private property managers have incentive to invest in GI practices. In 14 addition, some of green infrastructure’s additional community benefits such as potential climate cooling, 15 energy reduction, and neighborhood amenity improvement, are shared public-private benefits. Financing 16 and investment criteria that recognize and prioritize the additional benefits may be necessary to encourage 17 practices that meet multiple social, ecological, and economic objectives. 18
One problem is the manner in which water infrastructure projects are funded by local government. It is 19 common for such infrastructure to be funded either with general tax revenue or with the proceeds of bond 20 issues that are then paid back with taxes. Either way, it seems clear that municipalities have not been 21 willing to increase taxes to the level required to adequately maintain their water infrastructure, which 22 includes traditional waste water infrastructure as well as stormwater green infrastructure. There are 23 exceptions to this generalization, of course. The City of Chicago has over four million square feet of green 24 roofs on city buildings either completed or proposed. The city is determined to reduce stormwater volume 25 in its sewers through the evapotranspirative properties of these green roof projects. A number of other 26 cities around the country have also benefitted from large investments in green infrastructure. Yet, in order 27 for the skeptics to commit money to green infrastructure at this point in time, a strong financial incentive 28 appears to be required. 29
