Cudjoe Regional Wastewater Treatment Plant: Water Quality Issues Brian E. Lapointe, Ph.D. and Don Maynard, P.E.,C.G.

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1 Cudjoe Regional Wastewater Treatment Plant: Water Quality Issues Brian E. Lapointe, Ph.D. and Don Maynard, P.E.,C.G. Copyright Brian E. Lapointe 2014

2 Why is a Deep Well Needed? Water quality issues facing the Florida Keys Numeric and narrative nutrient standards Existing water quality problems in Cudjoe Basin Shallow wells will further impair surface waters Florida law requires a deep well

3 Water Quality Issues Facing the Florida Keys Nutrient and contaminant pollution Harmful algal blooms (toxins) Loss of corals, seagrasses, and overall biodiversity Decline of fisheries Emerging diseases and mortalities in biota (corals, soft corals, sea turtles) Economic impacts on Florida Keys

4 Nutrient pollution is pushing Florida s reefs beyond their ability to survive. Cleaning up the sewage in the Florida Keys would be a major step in the right direction Brian Lapointe

5 Florida s Narrative Nutrient Standard (47) (b) Nutrients. In no case shall nutrient concentrations of a body of water be altered so as to cause an imbalance in natural populations of aquatic flora or fauna.

6 Numeric Nutrient Standards F.A.C Parameter CK (Back Bay) UHK (Back Shelf) TN µm (0.25 mg/l) µm (0.23 mg/l) TP 0.29 µm (0.009 mg/l) 0.35 µm (0.011 mg/l) TN:TP Chlorophyll a 0.3 µg/l 0.7 µg/l

7 Cudjoe Regional WWTP: Background Big Pine Key Sugarloaf Key 9,060 equivalent dwelling units (edus) 4 shallow injection wells: 1.88 mgd maximum daily discharge Permitted Effluent Concentrations: BOD: mg/l TSS: mg/l Fecal Coliform: #/100 mls ph: TN: mg/l (428.6 µm) TP: mg/l (64.5 µm)

8 Loca%on of Shallow Wells at North End of Landfill

9 SHALLOW WELL INJECTATE TRAVELS QUICKLY TO SURFACE WATERS OF CUDJOE BASIN AND FURTHER DEGRADES THIS ALREADY IMPAIRED WATER BODY The karst geology of the area is pocketed with conduits and through the limestone; 1 of sewage effluent from shallow wells to surface waters will be hours to days if even one such conduit is reached by the injectate; 1 Even if no conduit is encountered, from shallow wells to surface waters will be at maximum three months; 2,3 Regardless of the nitrogen in the par@ally treated effluent is not removed during the transport period and will enrich the surface water, causing further degrada@on of an already impaired water body. 2 1: PAUL, J. H., M. R. MCLAUGHLIN, D. W. GRIFFIN, E. K. LIPP, R. STOKES, J. B. ROSE ESTUARIES 23: : LAPOINTE, B. E., J. O CONNELL, G. GARRETT BIOGEOCHEMISTRY 10: : MAYNARD, DONALD, 2014.

10 What Does a Conduit/Cavern Look Like? This photo shows a conduit in injection well IW2 at a depth of ~ 83 feet (25.5 meters). The 3-inch diameter conduit located above the depth numbers extends into the Key Largo limestone formation from the well.

11 Karst Conduits Allow RAPID Movement of Wastewater from Shallow Injec%on Wells into Surface Waters in the Lower Florida Keys 1 Studies used the marine bacteriophage HSIC and the Salmonella phage PRD1 as tracers of sewage contamina@on from a shallow injec@on well in the Saddlebunch Keys; The injec@on well tracer was first detected at a site most distant from the seed site, a channel that connected Sugarloaf Sound with the Atlan@c Ocean; The rate of tracer migra@on from the injec@on well to this channel ranged from 66.8 to 141 meters. h 1 ; These tracer studies showed a rapid movement of wastewater in a southeasterly direc@on toward the offshore reef tract with preferen@al movement channels. 1: PAUL, J. H., M. R. MCLAUGHLIN, D. W. GRIFFIN, E. K. LIPP, R. STOKES, J. B. ROSE ESTUARIES 23:

12 Tides and Rainfall Enhance Groundwater Flow Through Miami Oolite in the Lower Keys 1 A calibrated KV Associates Model 30 GeoFlo flow meter was used to make direct measurements of groundwater flow through Miami Oolite on Big Pine Key; Lateral groundwater flows increased 3- fold during as a result pumping; The highest lateral flows were associated with rainfall events that caused transient increases in flows; Average groundwater flow through porous Miami Oolite was ~ 1 meter/day, which is similar to calculated es@mate (~3 l/day); Although some phosphorus was removed by adsorp@on to limestone, ammonium and nitrate moved freely and discharged into adjacent surface waters. 1: LAPOINTE, B. E., J. O CONNELL, G. GARRETT BIOGEOCHEMISTRY 10:

13 Upward Buoyant Flow From Shallow Injec%on Wells Shallow wells will change surface water chemistry in Cudjoe Basin; Injectate will increase the slope of water table; This will cause flow of wastewater effluent into Cudjoe Basin; The gradient at the shallow well sites will cause movement of wastewater into Cudjoe Basin within hours to months.

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16 Monitor Well Data Show Nitrogen Contamina%on of Groundwater and Flow Into Cudjoe Basin 2 1

17 What is the Existing Water Quality In Cudjoe Basin? Two sites northwest of landfill sampled on August 5 th

18 Cudjoe Basin Exceeds TN and Chl a Standards TDN in Cudjoe Basin is ~ 6-fold higher than F.A.C. standard; High TDN concentrations support high chlorophyll a, ~ five-fold higher than F.A.C. Standard; TDN concentrations in Cudjoe effluent permitted to average 214 µm (3 mg/l TN), would enrich Cudjoe Basin above background levels that already exceed standards.

19 Ecosystem Response to Nutrient Enrichment: Harmful Algal Blooms in Cudjoe Basin

20 Mangrove Health Cudjoe Basin (Impacted) Vs. Big Torch Key (Reference) Pneumatophores overgrown by Batophora Clean Pneumatophores Batophora Halodule Thalassia

21 Seagrass Health Cudjoe Basin (Impacted) Vs. Big Torch Key (Reference) Thalassia fragmented by Batophora blooms Low density, low productivity Thalassia, no fish High density, high productivity Thalassia, abundant fish

22 Section (10) (h), Florida Statutes: If it is demonstrated that a discharge, even if the discharge is otherwise in compliance with this subsection, will cause or contribute to a violation of state water quality standards, the department shall: 2. Order the point or method of discharge changed.

23 Rule (13) shall be given to the from further nutrient enrichment of waters which are presently high in nutrient or to further nutrient and to further nutrient loadings.

24 Rule (15) F.A.C. which causes or contributes to new of water quality standards or to of is harmful to the waters of this State and shall not be allowed. Waters having water quality below the criteria established for them shall be protected and enhanced.

25 Summary Sewage injectate from shallow wells will impact surface waters within hours or days (conduit flow) to months (porous flow) and nitrogen, as well as other contaminants, will not be removed during groundwater transport; Wastewater nutrients and contaminants, (including nitrogen, phosphorus, and organic compounds, will impact surrounding surface waters; Injectate will increase flow of contaminated groundwater at WWTP into Cudjoe Basin; Nitrogen, Chl a and macroalgal blooms are evidence of exis@ng viola@ons of F.A.C. water quality standards in Cudjoe Basin; Regula@ons prohibit any addi@onal pollu@on.