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provides for water quality treatment and reduction of overall costs as fewer catchbasins,
curbing, conduits and other gray features are needed. LID is particularly effective in
meeting new water quality goals for storm water management, which traditional meth-
ods are not. LID can be economical if life cycle and total benefits are included. Economic
benefits are due to cost savings in land space for large ponds, below ground conduits,
curbs, catch basin and other gray features. Extra benefits exist such as promotion of nat-
ural cooling and higher property values. The storm drainage cost for shopping center in
the northeast was able to reduce costs by 26% or approximately $1 million using LID in-
stead of conventional approaches. A combined approach by Portland OR reduced costs
of combined sewer overload (CSO) management costs by from $144 M to $ 81 million.
LID enabled Chicago to divert 70 millions gallons in year from its CSO system resulting
in energy savings as well as green space benefits. New York City Department of Envi-
ronmental Protection expects to reduce its CSO costs from $6.8 billion using a gray-only
strategy to $5.3 billion using a mixed LID-gray strategy. Philadelphia Water Department
(2011) is also using a combined approach to beter manage CSOs. In addition, the com-
bined strategy will result in other benefits related to sustainability including reduced
Urban Heat Island efect, beter air quality, higher property values.
For present and future drainage systems, Heaney and Sansalone (2010) recommend
load management by removing pollutants from overland surfaces such as by street
cleaning. They also advocate for the use of real-time monitoring and control to improve
the management of urban drainage and sewage systems. As stated previously, the flexi-
bility of LID makes it atractive for adaptation; it can be added as needed to manage
precipitation changes over time - perhaps augmenting conventional approaches. The
mixing with conventional approaches may be needed as LID can only manage a few
inches of runoff. As WERF (2009) states, “ It is conceivable that, under the right condi-
tions, the long term answer may lie in green infrastructure strategies designed to re-
duce runoff and prevent it from entering combined sewers or leaky sewers. As more
and more green infrastructure is added to such a program year after year, it may be
capable of keeping up with the gradually increasing rainfall intensity phenomenon
over the course of time”, page 62. LID is also atractive for adaptation because of its co-
benefits and no-regrets aspects. Roseen et al. (2011) present several examples where sig-
nificant cost savings in adaptation may be possible using LID to help capture increases
instead of relying solely upon expansion of gray networks. Pyke et al. (2011) also present
an example. There still seems to be gap between practice and theory because, for ex-
ample, Philadelphia Water Department (2011) does not consider impacts of climate change
on urban drainage and only cite GHG mitigation as the climate change management
bene-fit of LID. However, Cohn (Alan Cohn, NYC DEP, personal communication, No-
vember 23, 2011) reports that New York City may consider how climate change impacts
storm water drainage quantities.
Water Supply
Besides the limited option of developing new sources, adaptation approaches include
demand management, new advanced technologies such as water reuse and drip irri-
gation, and use of new types of sources such as brackish water and rainwater harvesting
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