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

Home

PLOS ONE Identifying wastewater management tradeoffs in Kona, Hawai'i A Present I B Future permitted C All ATU upgrade D WWTP upgrade N I I I I I I I I I I I I I I I I I n V' A A I I NN01g1111W I ��i o I llmll%a//o � I I Nqt N change (kg/yr) / -8,902 - -597 'I ♦ WWTP M-596 - -38 I N (kg/yr) -37 - -1 1419 �-M 1 - 11 15 2 12 - 675 =420 - 12,761 km � - 676 - 42,314 -- - - - -- - - -- E Target low efficiency I F Target high efficiency I G Target low efficiency I H Target high efficiency + WWTP upgrade I + WWTP upgrade 0 I I I 04 I I I I I I I I 'IUI11u � I rp0� � I ♦ �N� ♦ � ♦ A I I �z I 41 I I I 1 I I I I I Fig 5. Marine water quality. Maps display (A) absolute loads of nitrogen (kg/year) under present conditions and (B-H) change (kg/year) relative to present conditions under all scenarios classified by geometrical intervals. -------------------------------------------------------------------------------------------------- htttlusaHoll,olr0/10.'1371/yoa jirinsll.Ipolne.0257125.0005 The present and future permitted build out scenarios incur zero costs because both assume that neither the cesspools nor the WWTP are upgraded. The WWTP upgrade scenario has the next lowest cost, requiring $160 million. The targeted cesspool conversion scenarios are roughly 67% more expensive with total costs of $267 million each, while the targeted cesspool conversion + WWTP upgrade scenarios cost $427 million, more than double the cost of only upgrading the WWTP. The all-ATU scenario is the most expensive, requiring $569 million, or approximately 3.5 times the cost of upgrading the WWTP alone. PLOS ONE I Ihuttttlps://doaa.oirg/10.1371/�OLuirirualll,lpoi ne.025712 a September 8, 2021 14 / 26