Well Treatment Facility Option 2. Treatment Facility Option 1. Pipeline Well Treatment Facility. Well and 69-02

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1 Trinity Engineering Firm Project Manager: Scott Griebling Project Engineer/Economic Specialist: Alicia Duran Junior Engineer/CAD Designer: Kari Leech Presentation Outline Project Background Project Goals Scope of Work Constraints and Criteria Distribution Preoxidation Treatment Final Design Conclusion Questions Project Background Location Stockton, California Water Quality Arsenic contaminated wells Exceed EPA regulations 10 parts per billion Effective January 2006 High levels of Silica Water Sources Groundwater 17 wells will exceed arsenic concentrations Surface water Stockton East Water District 55% of water supply Distribution Water quality varies by region Project Goals Provide Cost Effective Treatment Minimum modifications needed for the Stockton system Feasible residual disposal Scope of Work Lower arsenic level to 8 ppb Design for one cluster No residual disposal design Constraints Distribution Constraints Must Meet System Capacity Preoxidation Constraints EPA Water Quality Standards Silica Compatibility Treatment Constraints EPA Water Quality Standards Silica Compatibility Maximum Daily Demand (55.6 mgd) ph Compatibility 1

2 Criteria POU Located at ALL Family Residences POE Wellhead Treatment 17 Wellhead Facilities POE Cluster Treatment 4 Cluster Facilities 5 Wellhead Facilities Central Plant One facility (A lot of piping) Filtering POU Does not fulfill system capacity Appropriate for Small Communities Only (Pop < 10,000) Stockton, CA Pop > 150,000 POE Wellhead Treatment: weighted score 482 Pumped from Well Directly into Facility Low Level of Complexity Modular Units (Ease of Reproduction) Numerous Treatment Facilities POE Cluster Treatment: Weighted Score 527 Low Level of Complexity Combines Ideas of Wellhead and Central Plant Treatment Transported from Well to Treatment Facility Need for Both Wellhead and Cluster Facilities (different sizes means difficult construction) Central Treatment: Weighted Score 226 Centralized Location for Transportation Vast Pipe Network Large Central Treatment Facility Skilled Operators 2

3 Distribution Selection Cluster 4 Design Weight Comparison Well Treatment Facility Option 2 POE Clusters Chosen Least Expensive Most Flexible POE Cluster Treatment Facilities will be Designed for Cluster #4 Treatment Facility Option 1 Well and Pipeline Well Treatment Facility Cluster 4 Pipe Design Pipe 1: 8 in Diameter Connecting Well to Treatment Facility Pipe 2: 14 in Diameter Connection Wells 69-01,02 to Treatment Facility Pipe 3: 16 in Diameter Connecting Treatment Facility to Distribution Network Cluster 4 Pump Design Estimate of 45 ft Well Depth Determine Total Head & Flow Rate Pipe 1: 20 HP Pump Pipe 2: Current Pump Adequate Pipe 3: 50 HP Pump Distribution System Cost Total annualized cost $19,645 Interest rate of 5.65% Annualized over 20 years Preoxidation Electrostatic interactions are vital for ph range 7-8 Arsenite, H AsO 3 3 No electric charge 74% in Stockton water samples Arsenate, H AsO Electric charge 26% in Stockton water samples Necessary to oxidize all water treated 3

4 Chlorine Chlorine gas, Cl 2 Sodium Hypochlorite, liquid Calcium Hypochlorite, solid Permanganate, MnO - 4 Chlorine Gas, Cl2 Gas contained in cylinders Low cost Easy implementation Disinfection capability Low operator skill Toxic, can be deadly if released DBPs produced Operator Safety Calcium Hypochlorite Highly corrosive white solid Has approximately 70% available chlorine It is dissolved in water to create a concentrated solution Currently used for disinfection Disinfection capability Highly corrosive Moderately expensive Slightly complex Moderate operator skill DBPs produced Sodium Hypochlorite Liquid added to water Currently used for disinfection Easy to handle Disinfection capability Moderately expensive Moderate Operator Skill Must be stored in cool, dark, dry place Limited amount of supply can be purchased DBPs produced Permangnate Granular form that is soluble in water Mix powder with water to create a concentrated solution No DBPs produced High cost Very corrosive No disinfection capability Difficult to use May create pink water Higher operator skill Preoxidation Selection Chlorine Gas Most cost effective treatment Most easily implemented Very few DBPs Produced Complexity of system is low It can be easily modified for disinfection or regulation changes 4

5 Chlorine Gas Design Chlorine Gas Design lb cylinders 1.10 lbs/day Cl 2 Cylinder replaced every 3 months Grade 2 Operator Preoxidation Costs Total Annualized Cost Interest Rate 5.65% Annualized over 20 years Treatment Alternatives Coagulation and micro-filtration Sorptive media Reverse osmosis Blending Ion exchange Treatment Alternatives Constraint excluded alternatives Coagulation and sorptive media (iron based) Silica levels too high for effective removal Coagulation: large coagulant doses Sorptive media: low bed volumes Reverse osmosis Silica would foul membrane Treatment Alternatives Blending: weighted score 481 Cheap No chemical treatment No residuals Low labor cost No preoxidation needed No flexibility Piping costs 5

6 Treatment Alternatives Ion exchange: weighted score Effective in the presence of silica Stockton water has low sulfate Modular Requires preoxidation Residuals Treatment Selection Weight comparison Ion exchange chosen Cheaper More sustainable More flexible Treatment Design Treatment Design Ion exchange columns Six columns Four active, two standby / regenerating 700 gpm each 9 6 diameter, 8 straight wall height 1880 cubic feet of resin Regeneration: every 3 days Class III operator needed Treatment Design Cost Construction and capital cost: $1,464,654 Total annualized cost: $1,766,514 Interest rate of 5.65% used Annualized for 20 years Design Summary Distribution Cluster Treatment Preoxidation Chlorine Gas Treatment Ion Exchange 6

7 Design Cost Total annualized cost: Distribution cost: $19,645 Preoxidaion cost: $47,827 Treatment cost: $1,766,514 Total: $1,833,986 Design Construction Schedule Total construction time: eight weeks Start construction in early spring Conclusion Total project cost: $1.83 million $ / gal Residual handling Onsite evaporation ponds Solids shipped to hazardous waste landfill Questions? 7