2021-10-27 EMC Agenda item 5-b(i) Identifying wastewater management tradeoffs ... in Kona, Hawaii (RG)

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PLOS ONE Identifying wastewater management tradeoffs in Kona, Hawai'i A Present I B Future permitted C I All ATU upgrade D WWTP upgrade I I I I I I I I I I I I I I I I L I I I I I I e b I I I ♦ WWTP Potential habitat loss MPotential habitat recovery JEReef habitat z Nutrients plume=km F�N & P increase I N & P decrease I — — — — — — — — — — —I— — — — — — — — — — — E Target low efficiency I F Target high efficiency I G I I I I — — — — — — — — — — —I — — — — — — — — — — — Target low efficiency I H Target high efficiency + WWTP upgrade I + WWTP upgrade I I I I I I t, I I I I r ♦ ♦ _ I I I I I I I I I � I I I Fig 7. Marine habitat potential impacts. Maps display (A) the current exposure of marine habitat to SGD nutrients and (B-H) potential habitat loss or recovery due to the change in water -quality- under all scenarios. ht111usald¢t11 ors/I0) 1371/�oiirinalll.lpone.0257'125,gO(,)'7 nor the WWTP were upgraded. At the other end of the spectrum, N (-92 kg/d) and P (-15 kg/ d) decreased the most when all cesspools were upgraded to ATUs (the most effective nutrient removal technology considered) and the WWTP was upgraded. Changes in habitat quality were similarly highest for the all-ATU scenario (666 ha) and lowest for the future permitted buildout scenario (-319 ha). The highest benefit outcomes, in terms of nutrient reduction and potential improvement in marine habitat quality, come at a cost, however. Upgrading all cess- pools to ATUs has a price tag of $569 million, or at least double the cost of most other manage- ment options evaluated. PLOSONE IIhllltlps://doaa.ofg/10,1371/�OLuirlrllalll,lpoIne,025712a September8,2021 16/26