SEASONALLY FLOODED SALT FLATS. Enhanced Efficiency for Shallow Flooding as a Dust Control Measure

Transcription

1 SEASONALLY FLOODED SALT FLATS Enhanced Efficiency for Shallow Flooding as a Dust Control Measure

2 Objectives Enhance the shallow flood measure for improved efficiency and control, expand its applicability to clay soils, and utilize a waste product from the vegetation measure to contribute to a dust control strategy Design a clay soil preparation process that will allow for standing water in ponds and on playa areas proposed for dust control Design a process for the spreading of hyperbrines onto minimally treated clay surfaces to provide dust control with low water input Provide year-round protection using a locally developed brine that requires an order of magnitude less water than conventional shallow flood Utilize the discharge from vegetation projects and other dust control measures to develop the hyperbrine Actively mobilize and harvest salt resources available throughout the system to bring about the efficient and effective shallow flooding measure proposed Develop these objectives in concert to bring about technologically feasible and economically viable dust control enhancement

3 Opportunities associated with Managed Vegetation With 11,520 acres of managed vegetation, there will be about 5760 AF/yr of saline drain water produced in the summer months This drain water can be developed into a hyperbrine that, through summer solar evaporation, creates a salt flat of about 440 acres every year Salt flats are seasonally flooded, but require an order of magnitude less water than conventional shallow flood Water savings from such a measure, shich converts conventional shallow flood to flooded salt flats, could amount to about 11,000 AF/year

4 The Flooded Salt Flat Concept Feed from drain water 4 AF/ac/yr Pre-concentrator Salt flat Year 1 Year 2 Year 3 Year AF/ac/yr Each area converted to salt flat removes the same area from conventional shallow flood Feed from aqueduct 4 AF/ac/yr No change in flooded area 4 AF/ac/yr No change in water duty

5 Opportunities associated with harvest of brine pool solids Utilizing the brine pool as feed for the evaporative system producing salt flats increases the acres potentially converted from conventional shallow flood; no pre-concentrators required Up to 30,000 AF/yr of water could be saved almost immediately by building salt flat surfaces with brine pool waters Drain water from managed vegetation would provide 100% of the water required for maintenance of these surfaces in a seasonally flooded condition

6 Conceptual Project 1. Brine source (from managed vegetation) 2. Pre-concentrator ponds 3. Salt flat basins Pre-concentrators with dikes Salt flat basins with shallow berms

7 Clay Soil Design Criteria Develop construction and surface preparation techniques to produce a competent seal to minimize seepage Develop an appropriate brine concentration model to predict salt deposition Develop a management strategy to optimize salt flat deposition seasonally Develop a management strategy to minimize water use for on-going salt flat flooding in contour panels Construct a system suitable for rigorous evaluation of the skills and methods required for on-going operation

8 Develop construction and compaction techniques to produce a competent seal to minimize seepage Construct dikes utilizing construction methods to provide water retention capacity in preconcentrators sufficient to deal with pump-back costs Develop and test surface soil treatment techniques to effect sufficient subsidence to result in a competent seal Recovery/re-use of water lost to shallow groundwater Small earthen berms for hyperbrine distribution

9 Percent Develop an appropriate brine concentration model to predict salt deposition Brine model using laboratory and field concentration techniques, including seepage and evaporation data Analysis of brines and solid salts Development of the model for field conditions Design of optimum pond configuration Develop operational expertise Sample SG Entrain NaCl Carnalite Epsom SaltCake

10 Develop a management strategy to optimize salt flat deposition seasonally Identify seasonal differences in salt deposition: cold, hot, wet, and dry Identify critical temperature for seasonal salt changes, quantitative and qualitative Operate a pilot project with seasonal sorting of salts; operational window for summer and winter salts. Demonstration, scale model for economics, research model for technical data, operational model for physical properties of surface Conduct tests of required maintenance water duty for salt beds at different thickness

11 Develop a management strategy to minimize water use for on-going salt flat flooding in contour panels Evaluate contour panel condition for summer and winter deposition during summer and winter season for competence Test flooding strategies on both summer and winter salt beds during the dust season Construct a strategy for minimum water application to maintain emission control in each kind of salt bed

12 Construct a system suitable for rigorous evaluation of the skills and methods required for on-going operation Methods for operation of pre-concentrators to produce maximum quantity of hyperbrine Methods for recirculation of hyperbrines lost to seepage Methods for distribution of hyperbrines in contour panels

13 SEASONALLY FLOODED SALT FLATS Project Progress to Date

14 Project Elements in Progress Surface preparation Evaporation data Brine source development and evaluation Laboratory concentration data Field concentration data Model development Operational strategy development Recovery and re-use of seepage

15 Ponds 1-5 and Pond 7 compacted prior to hydration; seepage rate estimated using evaporation loss and depth measurement at about 0.03 inches/day Pond D extensively compacted at 70% of optimum density after ripping, tilling, and pre-leaching to wash out free salt. Seepage rate to be evaluated in May with brine concentration data Surface preparation

16 Inches / day Evaporation data On-site evaporation pans operated for more than a year. Correlations to long-term CIMIS values for evaporation calculated Regressions calculated for monthly differences between fresh water and concentrated brine evaporation rates Mean Daily Evaporation Pan 1 (Fresh) Pan 2 Pan 3 Pan4 Cimis 0.00 Sep-01 Oct-01 Nov-01 Dec-01 Jan-02 Feb-02 Mar-02 Apr-02 May-02 Jun-02 Jul-02 Aug-02 Sep-02 Oct-02

17 Brine source development and evaluation Begin with brine from managed vegetation drain water (SG ~ 1.02) Enhance with brine from a skimming well (SG ~ 1.23) Feed brine used is a mixture of these sources, SG ~ 1.08 Laboratory analysis of feed brine and its qualities

18 Laboratory concentration data Feed brine used to set up an evaporation and concentration project under laboratory (heat lamp) conditions Brines and solid salt collections made at regular intervals Use potassium (K) as a tracer as it is the last ion to precipitate as a solid Data to be used in model to predict chemistry and properties of complex salts deposited in the summer

19 Field concentration data Tanks with feed brine placed at ambient winter temperature at the project site Brine and solid salt samples taken at regular intervals Potassium (K) used as a tracer Winter salt deposition data generated

20 Model development Required model parameters are evaporation rates, leakage rate, feed brine quality, and concentration profiles All model parameters to be available by May 2003 Model developed by Agrarian in consultation with experts at IMC Trona, based on an IMC model Feed Brine Pond 1 Pond 2 Pond 3 Pond 4 Crystal Bittern Sea Pond 1 Pond 2 Pond 3 area N/A Area 1.68 ac Area 1.32 ac Area 0.72 ac Mg Mg Mg % Mg Mg % Mg Mg % SG SG SG SG SG SG SG Total Feed 4,580,937 kg Feed conversion (kg to volumes) 1 Evaporation Evaporation Evaporation 156,518 CF Evap 9.13 In/ Month Evap 9.13 In/ Month Evap 9.13 In/ Month 3.59 AF Ratio 1.53 Percent Ratio 1.42 Percent Ratio 1.23 Percent 6, mg kg PondEvap 9.94 In/ Month PondEvap 9.19 In/ Month PondEvap 7.95 In/ Month 200,920 TDS CF evap 60,621 CF total CF evap 44,020 CF total CF evap 20,780 CF total Test Mg Kg evap 1,716,598 Kg Total Kg evap 1,246,519 Kg Total Kg evap 588,421 Kg Total Leakage Leakage Leakage Rate In/Month Rate In/Month Rate In/Month Volume 3,708 CF Volume 2,913 CF Volume 1,589 CF Weight 104,994 waterbasis Weight 82,495 waterbasis Weight 44,997 waterbasis x SG 110,474 KgTotal x SG 90,220 KgTotal 52,270 KgTotal Pond 4 Area 0.28 ac 504,497 kg Mg Mg % SG SG 14,541 CF AF 4,944.1 MgMass Evaporation Evap 9.13 In/ Month 0.98 Mg wt % Ratio 1.05 Percent PondEvap 6.79 In/ Month CF evap 6,906 CF total Kg evap 195,555 Kg Total Leakage Rate In/Month Volume 618 CF Weight 17,499 waterbasis 21,440 KgTotal Flow downstream required to balance Ponds

21 Development of an Operational Strategy Utilization of two crystallizer ponds: one for summer and one for winter Characterization of depositions of summer and winter salt in these ponds: quality, depth, and phase changes with season Annual hydration requirements for both salt beds during the shallow flood season as designated On-going metering of all water delivered to the pond system Pond system intake Summer salt pond Winter salt pond

22 Recovery and re-use of seepage Grid of groundwater wells for determining depth to shallow groundwater Applied vs. evaporated water data Mathematical seepage model predicts pumping requirements and solids (TDS) qualitatively and quantitatively for recovery cycle

23 SEASONALLY FLOODED SALT FLATS On-going Project Development (FY )

24 On-going Project Development (FY ) Construct and calibrate a brine concentration model Construct additional dust control surfaces for summer and winter Hydrate and evaluate dust control surfaces Develop a model that evaluates the resource value of all inputs required presented as life cycle cost for the measure Evaluate quality of wildlife habitat created, including creation of habitat for snowy plovers

25 Construct and calibrate a brine concentration model Concentrate, collect and analyze solid salt and brine samples from the seasonally operated ponds for a 12 month period Measure depth, chemistry, and physical properties of the solid salt on the seasonally managed ponds External critique of calibrated model results with salt chemists and professional modelers eminent to the discipline

26 Construct additional dust control surfaces for summer and winter Construct to the east of the existing site at least two additional berms and panels for summer and winter operation Measure and evaluate salt deposition on each pond, and calculate depth, chemistry, physical properties, and area relationships Summer salt from Pond 7 Area for new construction

27 Flood and evaluate dust control surfaces Wind tunnel and other relevant evaluations of the treated panels when allowed to dry down Similar evaluation of the panels when hydrated at various levels Operation to vary thickness of salt deposition levels to evaluate the minimum depth required for efficient and effective dust control

28 Develop a model that evaluates the resource value of all inputs required: to be presented as life cycle cost with full absorption costing for the measure as a whole Develop the data Construct the model Calibrate the model Review with engineers, economists, and modelers Compare the measure with competing measures such as traditional shallow flood on sand, and managed vegetation as currently implemented on clay

29 Evaluate quality of wildlife habitat created, including creation of habitat for snowy plovers Determine quality of shallow water shorebird habitat in preconcentrator ponds Determine suitability of summer dry salt flat habitat for plovers on the contour panels with salt deposition Compare total variety of habitat values to other dust control measures

30 This modification of the Shallow Flood Dust Control Measure has considerable promise for high reliability and low life cycle cost with positive ecological benefits