An Ecological Wastewater Treatment Strategy Roseburg Urban Sanitary Authority (RUSA) ACWA 2017

Transcription

1 ACWA July 2017 An Ecological Wastewater Treatment Strategy Roseburg Urban Sanitary Authority (RUSA) ACWA 2017

2 RUSA WRRF: 7.9 mgd ADW Capacity, 3.0 mgd ADW Currently, Ammonia = 10.6 mg/l Nitrate + Nitrite = 8.9 mg/l

3 THE OPTIONS CONSIDERED Natural Treatment System on 340 acres: Phosphorus removal and temperature reduction with 70% of the water discharged to the river 18 Hole Golf Course plus all urban parks plus crop land irrigation: Three times as much land plus storage would be required for zero discharge reuse and the river needs the flow 7.9 mgd MBR plant: Replace the existing plant that is only at half capacity plus add cooling towers or chiller or wetlands for heat

4 WHY THE PROJECT WAS SELECTED COMMUNITY BENEFITS and COST COMPARISON The NTS utilizes sustainable climatic energy gradients for evaporative and radiant cooling The NTS cycles the basic elements of nutrients to higher level life forms that benefit the watershed The watershed scale NTS offers the public open green space, wildlife encounters, and educational opportunities The cost of obtaining tertiary treatment is an order of magnitude lower with an NTS than with an advanced mechanical, chemical, and energy based WRRF

5 Sustainability: It Doesn t get much Greener than this Transpires pure water vapor and oxygen Moves nutrients up the food chain so P and N become crawfish, insects, and plants that feed the river ecology Creates Soil and Stores Carbon Discharges Cool Clean Water to the River During the Low Flow Months creating a critical refugia stepping stone

6 South Umpqua River Sylman Creek/South Umpqua River Confluence Roseburg NTS Watershed Title Subtitle WRRF Sylman Creek Watershed

7 THE COST BENEFIT OF NATURAL TREATMENT A new 7.9mgd membrane plant to meet 0.13 mg/l total Phosphorus would cost about $100 million plus $5 million per year O&M A new plant would still not meet the temperature standard The existing WRRF is at 50% capacity and is projected to have 20 years of useable life remaining The existing WRRF meets all discharge limits except P and Temperature The existing WRRF O&M cost is $1.6 million/year Adding the Natural Treatment System costs $5 million plus increases O&M by $0.4 million per year for $2.0 million total annual O&M for the WRRF

8 Life Cycle Cost could be Offset with Future Land Sale Land value will go up, vegetation will gain value and ecosystem function At the end of 50 years the NTS will likely be within the expanded urban growth boundary and the increased land value will offset all costs of initial purchase, construction, and most of the cost of 50 years of O&M End of design life trade-in value is a huge benefit with land based systems.

9 THE PROCESS OF GETTING IT APPROVED A lot of meetings Proof of concept Willingness to try a new process A lot more meetings STIPULATED ORDER & MEMORANDUM OF AGREEMENT Between The Roseburg Urban Sanitary Authority and the State of Oregon Department of Environmental Quality Regarding NPDES Permits for the Roseburg Sewage Treatment Plant and the Total Maximum Daily Loads for Nutrients and Temperature for the South Umpqua River

10 Proof of Concept Lab studies for Phosphorus retention in undisturbed soil columns with effluent loading at various rates 6 week column study: 96-99% removal of Phosphorus Site Life to P Saturation = 50 years Influent P concentration: mg/l Effluent P concentration: 0.01 to 0.1 mg/l

11 THE PROCESS OF GETTING IT CONSTRUCTED Groundwater Monitoring Network Designed to Track Shallow Groundwater Recharge and Hyporheic Discharge to Sylman Creek On Site wells: 3 shallow and 3 deep, Off Site Wells: 4 Domestic or Irrigation 12 Piezometers, 50 Hand Auger Borings

12 Soil Tillage for Enhanced Infiltration Plow and Plant Degraded Farmed Wetlands and Meadows To Native Plants Chisel Plowing Preserves Sod but Allows Seeding into Loose Soil

13 75 miles of purple stripe pipe supplies precision water application

14 The 340 acre NTS provides tertiary treatment utilizing the full spectrum of natural processes in series and parallel Overland Flow Neuner Creek South Umpqua River WRRF Constructed Wetland And Deep Storage Pond High Rate Spray Irrigation Agronomic Rate Spray Irrigation Drip Irrigated Perimeter and Road Buffers

15 International Recognition Water Environment Federation (WEF) 2015 project of the year for Water Quality Improvement for significant, lasting, and measurable excellence in water quality improvement The natural treatment system is good for the community, good for the environment and good for the rate payers. We think it ll be a model for other communities in the future.

16 HOW IT S PERFORMED The NTS naturally removes nutrients with Precipitation and Sedimentation (making new soil) Chemical Reactions and Stabilization in Soil Consumption by soil organisms, plants, sheep and then humans Timber harvest Release to the river as insects, amphibians, plants, and low very concentrations of original constituents Habitat is everywhere

17 TP at SW5 rainfall SW Total Phosphorus discharge from NTS during Alum micro-dosing TP reduced from 0.23 mg/l to a minimum of mg/l by the end of 200 gal/d Alum micro dose trial Rainfall runoff causing flow spikes is the biggest variable TP (mg/l) gal/d 100 gal/d 150 gal/d 200 gal/d y = x R² = gal/d Rainfall (inch) At current flow rates 50 gpd of alum in May, June, and October offsets variables of flow spikes without creating floc /11/15 8/25/15 9/8/15 9/22/15 10/6/15 10/20/15

18 Total Phosphorus Increase in River The NTS was 100 percent compliant throughout the compliance period under the 8 microgram per liter (ug/l) TP increase alternative benchmark

19 Total Phosphorus Cost of Removal 16,000 lbs of phosphorus went to the NTS at about 4 mg/l and only 600 lbs was released to the river for 96% removal with no Alum O&M cost of P removal is $25/lb without Alum Total Phosphorus release concentration was reduced by about 20% more with Alum micro dose O&M cost of P removal is $125/lb with Alum for the most difficult to remove pounds (from 5 lbs/day down to 3.4 lbs/day discharged)

20 PERFORMANCE SUMMARY Tertiary Treatment to: 0.15 mg/l total phosphorus 2.0 mg/l total dissolved inorganic nitrogen 0.09 mg/l ammonia 2.4 mg/l total suspended solids 0.0 mg/l chlorine Averages 7 degrees C of heat removed from the effluent Averages 7.8 ph and 8.5 mg/l dissolved oxygen Nitrifying/Anammox wetlands remove nearly all ammonium from biosolids dewatering filtrate In summer the plume of water discharging from the NTS is cooler, lower ph, and higher dissolved oxygen than the river upstream or downstream for many miles creating a cold water refugia or stepping stone for migratory fish

21 LESSONS LEARNED Compliance in spring and fall during rain storms is most difficult Use of alum reduces risk of rapid flow changes in river or WRRF causing a peak in discharge Invasive plant management is ongoing A deep understanding of soil, water, and plant relationships is critical A small rate increase for a sustainable green solution is easier to get approved than a large rate increase for a mechanical plant upgrade.

22 FUTURE MANAGEMENT Refinement of geochemical augmentation with PAC replacing Alum More mitigation wetlands to bank for other projects Potential trade with neighbors to market excess P and heat removal to offset someone else's higher cost treatment Potential expansion to allow more passive management on a larger area to achieve similar total removal

23 QUESTIONS? Jim Baird