Vol.I_MasterPlan.pdf

June 20, 2000

Volume I – Report Volume I of IV

September 2002 K/J 004649.00

Lompoc Regional Wastewater Reclamation Plant Master Plan

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Table of Contents

List of Tables................................................................................................................................ iv

List of Figures............................................................................................................................... vi

List of Appendices........................................................................................................................ vi

List of Abbreviations.................................................................................................................... vii

List of Project Staff ......................................................................................................................viii

Section 1: Introduction

1.1 Background

1.2 Methodology

1.3 Organization

Section 2: Existing Wastewater Systems

2.1 Wastewater Collection and Conveyance

2.2 Wastewater Treatment

2.2.1 Liquid Processes

2.2.1.1 Influent Pumping Plant and Influent Flow

Measurement

2.2.1.2 Primary Clarifiers

2.2.1.3 Biofilter

2.2.1.4 Aeration Tank

2.2.1.5 Secondary Clarifiers

2.2.1.6 Disinfection

2.2.1.7 Process Flow Measurement

2.2.1.8 Effluent Flow Measurement

2.2.1.9 Discharge Facilities

2.2.2 Solids Handling

2.2.2.1 Gravity Sludge Thickener

2.2.2.2 Anaerobic Digester

2.2.2.3 Sludge Lagoons

2.2.2.4 Sand Drying Bed

2.2.2.5 Biosolids Storage

2.3 Industrial Pretreatment Program

Section 3: Regulatory Requirements and Impacts to Plant Facilities

3.1 Background

3.2 City of Lompoc Waste Discharge Requirements

3.3 Compliance Schedule

3.4 Monitoring and Reporting Program

3.5 Anticipated Future Requirements

Table of Contents (cont'd)

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3.5.1 Total Maximum Daily Loads

3.5.2 Future NPDES Permit Requirements

Section 4: Evaluation of Population, Flow, and Plant Loading

4.1 Historical Population and Flow Data

4.2 Other Recent Flow Measurements

4.3 Population and Flow Projections

4.4 Forecast of Constituent Loads

Section 5: Wastewater Control and Treatment to Address Projected Increased Flows

5.1 Influent Pumping Plant and Influent Flow Measurement

5.2 Primary Clarifiers

5.3 Biofilter

5.4 Aeration Tank

5.5 Secondary Clarifiers

5.6 Disinfection

5.7 Process Flow Measurement

5.8 Effluent Flow Measurement

5.9 Recommendations and Costs

Section 6: Wastewater Control and Treatment to Address Anticipated Nitrogen Removal Requirements

6.1 Existing Nutrient Removal Scheme

6.2 Nitrogen Removal Alternatives

6.3 Recommendations and Costs

Section 7: Wastewater Control and Treatment to Address Anticipated Metals Removal Requirements

7.1 Metals Removal Objectives

7.2 Evaluation of Metals Loading and Discharge Limits

7.3 Metals Reduction Alternatives

7.3.1 Source Reduction Investigation

7.3.2 River Water Quality Investigation

7.3.3 Laboratory Testing of Coagulants and Filtration for

Heavy Metals Reduction

7.3.4 Plant Optimization for Improved Metals Reduction

7.4 Additional Metals Removal Processes

7.4.1 Precipitation

7.4.2 Absorption Processes

7.4.3 Membrane Treatment

7.5 Effect of Metals Removal on Sludge

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7.6 Recommendations and Costs

Section 8: Wastewater Control and Treatment to Address Anticipated Phosphorous Removal Requirements

8.1 Phosphorus Removal Processes

8.1.1 Biological Phosphorus Removal

8.1.2 Chemical Phosphorus Removal

8.2 Recommendations and Costs

Section 9: Disinfection Alternatives

9.1 Sodium Hypochlorite/Aqua Ammonia Disinfection

9.2 Chlorine Gas

9.3 Ultraviolet Disinfection and Effluent Filtration

9.3.1 Results of Pilot Plant Study

9.3.2 Ultraviolet Disinfection

9.3.3 Effluent Filtration

9.4 Recommendations and Costs

Section 10: Solids Treatment and Disposal

10.1 Sludge Thickener

10.2 Sludge Digesters

10.3 Sludge Lagoons

10.4 Sand Drying Bed

10.5 Solids Disposal

10.6 Recommendations and Costs

Section 11: Electrical, Instrumentation, and Controls System

11.1 Existing Systems

11.1.1 Existing Electrical System

11.1.2 Existing Instrumentation and Controls

11.2 Proposed Upgrades and Improvements

11.2.1 Electrical System Upgrades

11.2.2 Instrumentation and Controls Upgrades

11.3 Recommendations and Costs

Section 12: Existing Structures and Equipment

12.1 Structural Improvements

12.1.1 Structural Evaluation

12.1.2 Upgrading Facilities to Meet Current Structural

Standards

12.1.3 Recommendations and Costs

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12.2 Corrosion Prevention and Protection

12.2.1 Corrosion Evaluation

12.2.2 Recommendations and Costs

12.3 Mechanical Equipment

12.3.1 Mechanical Evaluation

12.3.2 Recommendations and Costs

12.4 LRWRP Outfall Evaluation

12.5 Operator-Identified Concerns and Suggestions

12.5.1 Recommendations and Costs

Section 13: Maintenance and Storage Facilities

13.1 Maintenance Room

13.2 Vehicle Storage Facility

13.3 Painting, Sandblasting, and Landscaping Facilities

13.4 Recommendations and Costs

Section 14: Cost/Benefit Analysis

14.1 Net Project Costs

14.1.1 Capital Project Costs

14.1.2 Operating and Maintenance Costs (Savings)

14.1.3 Present Worth Costs

14.2 Benefits

14.3 New Plant Alternative

14.3.1 Cost Estimate

14.3.2 Financial Considerations

Section 15: Implementation

15.1 Contracting

15.2 Staging

15.3 Schedule

15.4 Sequencing

Section 16: References

List of Tables

2-1 Wastewater Generation by Source 2-2 LRWRP Design Data 3-1 Comparison of Effluent Metals to Interim Limits and Permit Limits 4-1 Summary of Flow Measurements 4-2 Flow Estimates and Projections

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4-3 Forecast of Constituent Loads 5-1 Liquid Process Evaluation Assumptions 5-2 Basic Primary Clarifier Characteristics 5-3 Primary Clarifier Evaluation Summary 5-4 Biofilter Loading Evaluation Summary 5-5 Aeration Tank Evaluation Summary 5-6 Basic Secondary Clarifier Characteristics 5-7 Secondary Clarifier Evaluation Summary 5-8 Chlorine Contact Tank Evaluation Summary 5-9 Estimated Project Costs to Provide Capacity and Redundancy Improvements 6-1 Solids Retention Time Comparison 6-2 Evaluation Matrix for BNR Alternatives 6-3 Estimated Project Costs Added for Nitrogen Removal 7-1 Metals Currently Exceeding Waste Discharge Permit Objectives, Effluent Objectives, and Degree of Treatment Needed 7-2 Additional Metals Evaluation Activities Currently Underway 7-3 Probable Metals Reduction by Alternative Treatment Processes 7-4 Metals Concentrations and Limits in Biosolids 7-5 Estimated Project Costs Added for Metals Removal 8-1 Estimated Project Costs Added for Phosphorus Removal 9-1 Advantages and Disadvantages of UV Disinfection 9-2 Estimated Project Costs Added for Filtration and UV Disinfection 10-1 Solids Removal Estimates 10-2 Basic Sludge Thickener Characteristics 10-3 Sludge Thickener Evaluation Summary 10-4 Basic Sludge Digester Characteristics 10-5 Sludge Digester Evaluation Summary 10-6 Sludge Gas Production Evaluation Summary 10-7 Estimated Costs of Recommendations for Solids Treatment and Disposal 11-1 Estimated Costs for Electrical, Control, and Instrumentation Improvements 12-1 Estimated Costs for Seismic Rehabilitation of Existing Buildings 12-2 Estimated Cost of Recommendations to Address Structural Issues 12-3 Buried Iron and Steel Pipe Specifications 12-4 Estimated Cost of Recommendations for Addressing Corrosion 12-5 Life Cycle Cost Evaluation of Blower Drive Alternatives 12-6 Estimated Cost of Recommendations to Address Mechanical Issues 12-7 Cost Summary for Blasting, Priming, and Painting Digesters 12-8 Cost Summary for Snail Shell Removal 12-9 Estimated Cost of Recommendations to Address Operator Concerns 13-1 Estimated Cost for Maintenance and Storage Facilities Improvements 14-1 Project Identification and Costs 14-2 Rating System for Non-Quantifiable Benefits 14-3 Project Identification and Benefits 14-4 Financial Considerations of New Plant vs. Existing Plant 15-1 Implementation Schedule

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15-2 Staging of Projects

List of Figures

2-1 Location Map 2-2 Wastewater Service Area 2-3 Existing Schematic Flow Diagram 2-4 Plant Layout 6-1 Existing Process – RF/AS 6-2 Alternative 1: RF/AxAS 6-3 Alternative 2: RF/TFmAxAS 6-4 Alternative 3: RF/TFmeRxAS 6-5 Alternative 4: RF/ASeAxAS 6-6 Alternative 5: RF/meRxAS 6-7 Alternative 6: mAxARF/TF/AS 6-8 Alternative 7: mLE 8-1 Anaerobic Selector for P Removal Anaerobic/Anoxic (A20) Process 8-2 Recommended Phosphorus Removal Alternative 11-1 Existing Electrical Distribution System Single Line Diagram 11-2 Proposed Electrical Distribution System Single Line Diagram 11-3 Operator Interface Needs 13-1 Existing Maintenance Facilities 13-2 Potential Maintenance Room Configuration 13-3 Potential Vehicle Storage Building Configuration 13-4 Potential Landscaping, Painting, and Sandblasting Building Configuration

List of Appendices

A Pilot Plant Study Technical Report B Waste Discharge Requirements Order No. 01-87 C Flow Projections Technical Memorandum D Influent Flow Measurement Technical Memorandum E Dispersed Suspended Solids/Flocculant Suspended Solids Technical Memorandum F Biological Nutrient Removal Alternatives Technical Report G Structural Condition Survey and Evaluation Technical Report

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List of Abbreviations

ADWF Average Dry Weather Flow AISC American Institute of Steel Construction BNR Biological Nutrient Removal BOD Biochemical Oxygen Demand CBOD Carbonaceous Biochemical Oxygen Demand CCT Chlorine Contact Tank cfm cubic feet per minute CMU concrete masonry unit COD Chemical Oxygen Demand CTR California Toxics Rule CWA Clean Water Act DO Dissolved Oxygen EO Executive Officer f:m food to microorganism ratio gpd gallons per day gpm gallons per minute LRWRP Lompoc Regional Water Reclamation Plant MCRT Mean Cell Residence Time mgd million gallons per day mLE Modified Ludzack-Ettinger MLR Mixed Liquor Recycle MLSS Mixed Liquor Suspended Solids MPN Most Probable Number MRP Monitoring and Reporting Program NOD Nitrogenous Oxygen Demand NPDES National Pollutant Discharge Elimination System O&M Operations and Maintenance ORP Oxidation Reduction Potential PDWF Peak Dry Weather Flow PE Primary Effluent PLC Programmable Logic Controller POTW Publicly-Owned Treatment Works PSF Primary Sludge Fermenter PWWF Peak Wet Weather Flow RAS Return Activated Sludge RF/AS Roughing Filter/Activated Sludge RWQCB Regional Water Quality Control Board SBOD Soluble Biological Oxygen Demand SCADA Supervisory Control and Data Acquisition SRT Sludge Residence Time/Solids Retention Time SWRCB State Water Resources Control Board TBOD Total Biological Oxygen Demand

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TDS Total Dissolved Solids TIE Toxicity Identification Evaluation TMDL Total Maximum Daily Load TOL Total Organic Loading TRE Toxicity Reduction Evaluation TSS Total Suspended Solids UBC Uniform Building Code USEPA U.S. Environmental Protection Agency UV Ultraviolet VAFB Vandenberg Air Force Base VFA Volatile Fatty Acids VSS Volatile Suspended Solids VVCSD Vandenberg Village Community Services District WAS Waste Activated Sludge WWTP Wastewater Treatment Plant

List of Project Staff

Kennedy/Jenks Consultants Engineering/Pilot Study Don Barraza, P.E.

John Jenks, P.E.

Mike Kang, P.E.

Kristine McCaffrey, P.E.

Brad Milner, M.A.

Bob Owens, P.E.

Nick Peros, P.E.

Bob Ryder, P.E.

Drafting Jimmie Guzik Mike Kang, P.E.

Report Reproduction Erin Guzman Teresa Fuentes Kim Allender Sylvia Nissim

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Equipment Suppliers Parkson Corporation Suntec Environmental

City of Lompoc Council Dick DeWees, Mayor Janice Keller Michael Siminski Will Schuyler DeWayne Holmdahl

Regional Wastewater Reclamation Plant Staff Utility Director – Gary P. Keefe Wastewater Division Wastewater Superintendent – Dale Ducharme Operations Supervisor – Ronald Dickerson Facilities Maintenance Supervisor - Donald J. (Jeff) Palmer Wastewater Collection Supervisor – Kenneth Ryan Laboratory Chemist – Dr. David Lewis

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Section 1: Introduction

The City of Lompoc Wastewater Master Plan serves to update the existing 1972 Master Plan for the Lompoc Regional Wastewater Collection and Treatment System. It is principally focused on the treatment and effluent disposal systems, not the collection system, and specifically addresses known problems and needs for the Lompoc Regional Water Reclamation Plant (LRWRP), including process-related concerns, obsolescence, and physical condition assessments. This Master Plan is intended to present a long-range program addressing the wastewater treatment needs of the City of Lompoc for the next 20 to 30 years.

1.1 Background

The City’s first wastewater treatment facility was an Imhoff tank located near present day V Street and North Avenue circa 1916. The effluent discharge was near the present northernmost end of V Street.

The second plant, circa 1942, was built by or in conjunction with the U.S. Army as part of the build up of Camp Cook as an Army training base during WWII. This facility was an oxidation pond located at Central and V Streets.

In 1960, the Lompoc Water Pollution Control Facility was constructed at the current site to replace the oxidation ponds and provide secondary treatment by biological filtration. The facility had an average dry weather flow (ADWF) capacity of 1.76 million gallons per day (mgd). It was originally designed and constructed as a two-stage trickling filter system with discharge into the Santa Ynez River. Between 1961 and 1966, a number of modifications to the plant were undertaken, including the incorporation of the previously-abandoned 35 acre-foot effluent oxidation pond into the system and rerouting of return digester supernatant application point from the primary trickling filter to the primary sedimentation tank.

Between 1974 and 1977, the LRWRP in its current configuration was constructed. The existing plant consists of one-half of a 10-mgd advanced secondary treatment facility. The LRWRP has operated very well consistently providing complete nitrification. The California Water Environment Association (CWEA) awarded the LRWRP its Plant of the Year award in both 1978 and 1987. The LRWRP has also won a Beautification Award from the City.

The existing facilities of the LRWRP have changed little from what was constructed in the mid- 1970s. Accordingly, some of the 25-year-old facilities are reaching the end of their service life, while others have been rendered obsolete by technological changes. Additionally, substantial changes in the regulatory environment have occurred over the 25-year period and the LRWRP is required to meet more stringent discharge requirements than it was in its early days. These regulations will continue to become more stringent over the next few decades.

1.2 Methodology

The Master Plan was developed through the following activities:

● Review of operations and maintenance (O&M) records for the LRWRP.

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● Discussions with, and input from, plant operations and maintenance staff.

● Independent effluent flow measurement.

● Review of plans and specifications for the 1974-1977 construction of the LRWRP.

● Review of the new waste discharge requirements for the LRWRP, as well as other relevant current and future regulatory requirements.

● On-site physical condition assessments of structural, electrical/instrumentation, and mechanical systems.

● Performance of a pilot study to evaluate the effectiveness of using effluent polishing filtration and ultraviolet disinfection. A Technical Report discussing the results of the pilot study is included as Appendix A.

● Preparation of process calculations to evaluate the effectiveness of various liquid and solids process schemes to achieve the necessary effluent limits.

Based on these activities, a recommended list of improvements was prepared and cost estimates were developed for the individual improvements and the Master Plan as a whole.

1.3 Organization

This Master Plan is organized as follows:

● Section 1, Introduction, introduces the Master Plan and identifies its structure.

● Section 2, Existing Wastewater Systems, describes the City’s existing wastewater collection, conveyance, treatment, and disposal facilities.

● Section 3, Regulatory Environment, discusses existing and anticipated regulations and effluent limits that may affect the City’s wastewater operations, including National Pollutant Discharge Elimination System (NPDES) permit requirements and Total Maximum Daily Loads (TMDLs).

● Section 4, Evaluation of Population, Flow, and Plant Loading, reviews historical population and flow data, develops population and flow projections, and estimates plant loading based on those projections. This information is critical in developing estimates of future LRWRP needs.

● Section 5, Wastewater Control and Treatment to Address Projected Increased Flows, evaluates the existing facilities at the LRWRP to determine if they are adequate for handling projected flow increases.

● Section 6, Wastewater Control and Treatment to Address Anticipated Nitrogen Removal Requirements, presents process modifications that would allow the LRWRP to achieve a 10 mg/l effluent limit for nitrogen.

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● Section 7, Wastewater Control and Treatment to Address Anticipated Metals Removal Requirements, presents process modifications that could allow the LRWRP to achieve the metals removal required by its NPDES permit.

● Section 8, Wastewater Control and Treatment to Address Anticipated Phosphorous Removal Requirements, presents process modifications that would allow the LRWRP to achieve a 0.5 mg/l effluent limit for phosphorus.

● Section 9, Disinfection Alternatives, discusses the performance of the existing disinfection system and presents alternatives for disinfection, including ultraviolet (UV) disinfection.

● Section 10, Solids Treatment and Disposal, presents the results of an assessment of the existing solids handling facilities at the LRWRP and evaluates potential alternatives for addressing process changes or improving efficiencies.

● Section 11, Electrical, Instrumentation, and Controls System, provides a review of the existing control loops, operating units, and sensors and discusses potential upgrades, including those necessary to accommodate recommended process modifications.

● Section 12, Existing Structures and Equipment, summarizes the results of field investigations into the condition of the LRWRP and its outfall from a structural, corrosion, and mechanical perspective.

● Section 13, Maintenance and Storage Facilities, discusses the limitations of LRWRP’s existing maintenance facilities and presents alternatives for providing improved maintenance shop and vehicle maintenance and storage facilities.

● Section 14, Cost/Benefit Analysis, uses the cost information presented throughout the Master Plan to assess the relative costs and benefits of the improvements under consideration.

● Section 15, Implementation, presents a capital improvements program for the LRWRP based on the long-term costs and benefits of each alternative and discusses how the recommended improvements can be implemented, including phasing, schedule, and sequencing.

Many of these issues are addressed in greater detail in individual Technical Reports and Memoranda, which are included as Appendices to this Master Plan.

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Section 2: Existing Wastewater Systems

The City of Lompoc is located within the Lompoc Valley in the western part of Santa Barbara County, approximately 55 miles northwest of the City of Santa Barbara, as shown in Figure 2-1.

The LRWRP receives wastewater from three primary entities: the City of Lompoc, Vandenberg Village Community Services District (VVCSD), serving Vandenberg Village, and Vandenberg Air Force Base (VAFB). Wastewater from Mission Hills and Federal Correctional Institute are not treated at LRWRP. The areas of the Lompoc Valley that are served by the LRWRP are indicated in Figure 2-2.

2.1 Wastewater Collection and Conveyance

Wastewater is collected by three regional component systems -- those for VVCSD, VAFB, and the City of Lompoc – and conveyed to LRWRP. VAFB and VVCSD retain ownership and direct responsibility for wastewater collection and transport systems up to the point of discharge into the LRWRP and/or interceptors owned and operated by the City. The VAFB interceptor line connects to the City's system directly opposite the LRWRP.

The majority of wastewater generated within the City and surrounding region is domestic in nature, primarily from single and multi-family residential uses. Wastewater from commercial, light industrial, and military (VAFB) sources is also treated at LRWRP. Table 2-1 presents the wastewater generation by source. There are approximately 9,000 connections to the sewer system within the City limits.

TABLE 2-1

WASTEWATER GENERATION BY SOURCE

Land Use Percentage Contribution Residential 80 Commercial 10 Industrial 5 Military 5

2.2 Wastewater Treatment

The LRWRP consists of one-half of a 10 MGD wastewater treatment plant that was constructed in 1976-1977. Since that time, modifications have been made to several systems to comply with changing environmental and safety regulations. The LRWRP has a current Average Dry Weather Flow (ADWF) capacity of 5.0 MGD and currently operates at approximately 4.0 MGD.

Influent flows to the LRWRP are discussed in more detail in Section 4.

Table 2-2 presents an overall summary of the design basis for the liquid and solids process systems at the LRWRP. Figure 2-3 presents a schematic flow diagram of the existing processes, with the existing general layout of the LRWRP shown in Figure 2-4. Detailed discussion of existing operating conditions are presented on a process-by-process basis below.

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The LRWRP is equipped with continuous monitoring equipment at various locations to track pH, dissolved oxygen, chlorine residual, temperature and other parameters. Daily process monitoring also includes collection of multiple samples with the plant, with analysis performed in an on-site laboratory. A comprehensive system of reporting and record keeping is in place.

Data from the monitoring are used to make operational and process changes as necessary.

TABLE 2-2

LRWRP DESIGN DATA

Criterion Value Design Loading

Population Equivalent (people) 43,750 Unit Loading (gpcd) 114

Wastewater Flow Average Dry Weather Flow (mgd) 5.0 Peak Dry Weather Flow (mgd) 9.1 Peak Wet Weather Flow (mgd) 16.0

Loading Biochemical Oxygen Demand (mg/l) 300 Biochemical Oxygen Demand (thousand lbs/day) 12.5 Suspended Solids (mg/l) 300 Suspended Solids (thousand lbs/day) 12.5 Ammonia Nitrogen as Nitrogen Average (mg/l) 25 Average (thousand lbs/day) 1.04 3 Hour Peak (mg/l) 40 3 Hour Peak (thousand lbs/day) 1.67

Influent Pumping Mechanically Cleaned Bar Screens Number 2 Capacity Each (mgd) 17 Maximum Velocity through Screen (fps) 3 Screening Grinding Pumps Number 2 Capacity Each (gpm) 250 Screenings, Wet Basis (ft3/hr) 60 Influent Pumping Units Number 4 Capacity Each (mgd) 17 Total Head (ft.) 50.0

Primary Sedimentation Tanks Tanks Number 2 Effective Diameter (ft.) 79 Side Water Depth (ft.) 20 Overflow Rate ADWF Basis (gpd/sf) 510

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TABLE 2-2

LRWRP DESIGN DATA

Criterion Value PWWF Basis (gpd/sf) 1,632 Detention Time ADWF Basis (hrs.) 3.9 PWWF Basis (hrs.) 1.2 Primary Sludge Pumps Number 2 Capacity Each (gpm) 250 Total Head (ft.) 30 Primary Scum Ejectors Number 2 Capacity Each (gpm) 250 Total Head (ft.) 75 Assumed Primary Treatment Efficiency BOD5 Removal (%) 35 Suspended Solids Removal (%) 65 Primary Effluent Quality BOD5 (mg/l) 195 BOD5 (thousand lbs./day) 8.13 Suspended Solids (mg/l) 105 Suspended Solids (thousand lbs./day) 4.38 Biological Oxidation Total System Volume(a) (ft3) 245 Volumetric Loading (lbs. BOD5/thousand ft3/day) 33.2

Biofilters Filters Number 1 Diameter Each (ft.) 85 Depth of Media Each (ft.) 20 Volume Each (thousand ft3) 113.4 Loading Volumetric Loading (lbs BOD5/thousand ft3/day) 71.7 Hydraulic Loading (gpm/sf) 1.35 Biofilter Circulation Pumps Number 2 Capacity Each (mgd) 11 Total Head (ft.) 40 Ventilation Fans Number Each Biofilter 4 Capacity Each (cfm) 2,000 Air Supply Rate (cf air/lbs. BOD5 applied) 1,420 Biofilter Effluent Quality BOD5 Unsettled (mg/l) 110.1 BOD5 Settled (mg/l) 25.2

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TABLE 2-2

LRWRP DESIGN DATA

Criterion Value Settled Suspended Solids (mg/l)(b) 42.5 BOD5 Unsettled (thousand lbs/day) 4.59 BOD5 Settled (thousand lbs/day) 1.05 Suspended Solids (thousand lbs/day) 1.75 Nitrogenous Oxygen Demand (thousand lbs/day) 4.8

Activated Sludge Aeration Aeration Tanks Number 1 Length Each Pass (ft) 145 Width Each Pass (ft) 30 Water Depth (ft) 15 Time Under Aeration ADWF Basis (hrs) 4.7 PWWF Basis (hrs) 1.5 Assumed Food to Microorganisms Ratio 0.3 Mixed Liquor Suspended Solids (mg/l)(c) 3,050 Mean Cell Residence Time (days) 14.5 Volumetric Loading (lbs BOD5/thousand ft3/day) 35.2 Volumetric Loading (lbs NOD+ BOD5/thousand ft3/day) 72.0 Air Requirements 3-Hour Peak (thousand cfm) 10.3 Average (thousand cfm) 8.5 Aeration Air Blowers Number 3 Capacity Each (cfm) 5,200 Waste Mixed Liquor Pumps Number 2 Capacity Each (gpm) 500 Total Head (ft) 25 RAS Recycling Pumps Number 1 Capacity Each (mgd) 1.25 Total Head (ft) 12 Secondary Sedimentation Tanks Tanks Number 3 Diameter Each (ft) 65 Side Water Depth Each (ft) 16 Solids Loading (lbs/sf/day)(d) 28.8 Overflow Rate ADWF Basis (gpd/sf)(e) 754 PWWF Basis (gpd/sf) 1,609 Return Activated Sludge Pumps

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TABLE 2-2

LRWRP DESIGN DATA

Criterion Value Number 5 Capacity Each (mgd) 1.67 Total Head (ft) 13.5 Chlorination Pre-Chlorinator Number 1 Capacity (lbs/day) 2,000 Assumed Maximum Dosage (mg/l) 15 Average Dosage (mg/l) 5 Post-Chlorinators Number 2 Capacity Each (lbs/day) 2,000 Maximum Capable Dosage, ADWF Basis (mg/l) 100 Average Dosage (mg/l) 10 Chlorine Evaporators Number 2 Capacity Each (lbs/day) 8,000 Rapid Mix Tank Number 1 Length (ft) 9 Width (ft) 7 Liquid Depth (ft) 16 Mixing Time, PWWF Basis (seconds) 40 High Energy Mixer Number 1 Mixing Horsepower 10 Chlorine Contact Tanks Number 1 Number of Passes Each Tank 4 Length Each Pass (ft) 80 Width Each Pass (ft) 7 Water Depth (ft) 10 Contact Time, PWWF Basis (minutes) 15 Effluent Control Structure Effluent Pumps Number 2 Capacity Each (mgd) 8.5 Total Head (ft)(f) 38 Reclaimed Water Pumps Number 1 Capacity Each (mgd) 9.1 Total Head (ft) 120 Utility Water Pumps (High Pressure)

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TABLE 2-2

LRWRP DESIGN DATA

Criterion Value Number 2 Capacity Each (gpm) 250 Total Head (ft) 255 Utility Water Pumps (Low Pressure) Number 2 Capacity Each (gpm) 500 Total Head (ft) 130 Gravity Thickener Dilution Water Pumps Number 1 Capacity Each (gpm) 700 Total Head (ft) 25 Assumed Effluent Quality Suspended Solids (mg/l) 15 BOD5 (mg/l) 15 Ammonia Nitrogen (mg/l) 0.1 Coliform Organisms (MPN/100 mL) 2.2 Emergency Holding Basin Number 1 Storage Capacity (mg)(g) 20 Grit Separation Grit Separators Number 2 Capacity Each (gpm)(h) 250 Grit Washer Number 1 Capacity (lbs grit/hr) 2,000 Waste Solids Thickening

Gravity Thickeners Number 1 Diameter (ft) 55 Side Water Depth (ft) 9 Solids Loading (lbs/sf/day) 3.4 Overflow Rate (gal/sf/day)(i) 700 Detention Time (hours) 2.7 Assumed Thickened Solids (%) 6 Thickened Solids Pumps Number 2 Capacity Each (gpm) 250 Total Head (ft) 200 Thickener Scum Ejectors Number 1 Capacity Each (gpm) 30 Total Head (ft) 75

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TABLE 2-2

LRWRP DESIGN DATA

Criterion Value Anaerobic Digestion Digesters Number 2 Diameter Each (ft) 55 Side Water Depth (ft) 28.5 Total Capacity Each (thousand ft3) 67.2 Primary Solids Loading (thousand lbs/day) 5.7 Secondary Solids Loading (thousand lbs/day) 2.2 Solids Loading (lbs volatile soilids/ft3/day)(j) 0.06 Assumed Volatile Solid Reduction (%) 55 Assumed Gas Production (thousand ft3/day) 73 Assumed Gas Production (ft3/lbs volatile solids reduced) 18 Digested Sludge Lagoons Number 2 Gross Storage Volume Each (thousand ft3) 481 Depth (ft) 12 Time to Fill Each (yrs) 2

Notes:

(a) Based on 1 ft3 of biofilter media equal to 1 ft3 aeration tank volume.

(b) Solids from biofilter sloughs only.

(c) Including biofilter solids.

(d) Based on 50 percent RAS return and one tank out of service.

(e) Assumes one tank out of service.

(f) Assumed maximum river water surface elevation 72.00.

(g) Based on maximum basin water surface elevation of 65.00.

(h) Based on inlet pressure of 9 psi.

(i) Solids flow augmented with plant effluent.

(j) Based on 70 percent volatile primary solids. 90 percent volatile secondary solids.

2.2.1 Liquid Processes

The existing LRWRP liquid treatment processes comprise a secondary treatment system including biological nitrification and disinfection.

2.2.1.1 Influent Pumping Plant and Influent Flow Measurement

The LRWRP receives influent flow from three locations: the City of Lompoc, VVCSD, and VAFB.

Flows from VVCSD and VAFB are separately metered for billing purposes. Influent flows from the City are not separately metered and no total influent flow measurement is made.

Raw wastewater enters the LRWRP through two 30-inch diameter trunk sewers and is combined at a central manhole. At the headworks, large solids are removed using 6 mm screens. Screenings are washed, compacted and transported to the City landfill for disposal.

Four influent pumps convey the screened influent to a splitter box upstream of the primary clarifiers.

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The original installation screens were coarse with the screenings ground and returned to the incoming flow. Subsequent to original construction, the screens were changed from coarse to fine screens with considerably improved results, including significant reduction in clogging of downstream pumping and piping.

The pump drives have been changed to variable speed for the purpose of flow matching. The screens have a flow capacity for 17 MGD each while each pumping unit is rated at 8.6 MGD.

Space was provided in the pumping plant design for a third screen and a fifth pump.

Wastewater is also prechlorinated and aerated in the headworks. Additionally, a 20 million gallon emergency holding basin exists at the head of the LRWRP to divert and store wastewater during extreme flow conditions to prevent exceedance of the hydraulic capacity of the downstream processes.

It is reported that the existing influent pumping plant operates well, particularly with installation of the finer screens and compactor.

2.2.1.2 Primary Clarifiers

Primary treatment involves sedimentation with primary grit removal. There are two existing circular primary clarifiers, each 79 feet in diameter with 10 feet side wall depth. Primary effluent overflows into circular weirs and is conveyed to the biofilter. Rotary sweeps within the primary clarifiers move settled solids from the bottom of the clarified to a central sump where they are then pumped with individual sludge pumps to the downstream grit removal processes. The clarifier sweeps also collect grease, scum and other floatable materials on the surface of the clarifier; pneumatic scum ejectors convey the scum to the anaerobic digester.

Typical clarifier detention time is approximately 3 to 4 hours. Typical removal efficiencies are 65 percent of the influent suspended solids and 35 percent of the influent biochemical oxygen demand (BOD). The primary sludge is typically less than one-half of one percent solids. The primary clarifiers are operated to maintain continuous sludge withdrawal.

Currently, only primary clarifier no. 2 is being operated. Primary clarifier no. 1 requires modifications as outlined in Chapter 12.

2.2.1.3 Biofilter

Secondary treatment utilizes a single biofilter with downflow media, coupled with an aeration tank, to remove carbonaceous BOD (CBOD) and to nitrify. Due to a low concentration of alkalinity, magnesium hydroxide is added. There is a single 85-foot diameter biofilter containing 20 feet of plastic media, which is approximately 113,400 cubic feet in volume.

This biofilter receives clarified, primary effluent, which is pumped from the primary clarifiers.

Recirculation ahead of discharge to the aeration tanks is provided. Water is recirculated across the biofilter using the recirculation pumps. Large fans deliver air through the filter media to promote biological growth.

The biofilter serves primarily to reduce the organic loading to the downstream aeration tank.

Soluble BOD (SBOD) removal efficiency across the biofilter is around 75 percent.

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The existing biofilter is operating as designed and is capable of producing an acceptable effluent when operating under current loading conditions. The biofilter has been operating continuously for more than 20 years and, due to a lack of redundancy, cannot be removed from operation for major rehabilitation.

2.2.1.4 Aeration Tank

Effluent flows by gravity from the biofilter to the single aeration tank, which is operated as a plug flow biological reactor. This tank has two compartments that operate in series. Each compartment is 145 feet in length, 30 feet in width and 15 feet in depth. The volume of each compartment is 488,070 gallons.

Aeration blowers deliver diffused air into the tank to promote microbial degradation of suspended waste particles. Microorganisms, such as stalked ciliates, annelid worms, and rotifers, consume the organic matter, effectively reducing soluble BOD from the flow stream.

Process monitoring equipment is used to control operation of the tank. Currently, the tank is operated so as to accomplish added soluble BOD reduction and to nitrify. Typical detention times in the aeration tank are 4 to 5 hours.

The existing aeration tank is functioning well in combination with the existing biofilter and could continue to do so for the near future. The aeration tank has been operating continuously for more than 20 years and, due to a lack of redundancy, cannot be removed from operation for major rehabilitation.

An investigation of the biological flocculation caused by the performance of the aeration system provided positive results. Measurements were made of sludge volume index in the mixed liquor and of flocculant suspended solids. The results indicate that the flocculation is well developed and very settleable. Based on the secondary effluent total suspended solids (TSS), additional flocculation time in the secondary clarifiers would increase the reliability of maintaining the TSS at 10 mg/l or less throughout varying diurnal conditions.

2.2.1.5 Secondary Clarifiers

Effluent from the aeration tank (mixed liquor) flows into a distribution channel that is used to feed the secondary clarifiers. There are three existing circular secondary clarifiers, each 65 feet in diameter by 16 feet side wall depth.

The clarifiers are typical circular centerwell design that remove the lighter particulates present in activated sludge mixed liquor. Secondary effluent overflows circular weirs in each tank and flows by gravity to the chlorine contact tank for disinfection. Rotary sweeps within the secondary clarifiers move settled solids at the bottom to a central sump. Return activated sludge (RAS) pumps convey a portion of the settled solids back to the aeration tank. Waste activated sludge (WAS) pumps convey the remainder to the gravity thickener.

Typical detention times are 2 to 3 hours. Effluent quality from the secondary clarifiers is relatively consistent with an average BOD concentration of 10 mg/l and average TSS concentration of 10 mg/l. The secondary clarifiers appear to be functioning well under current loading conditions.

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2.2.1.6 Disinfection

Final effluent disinfection is a combination of chlorination (using aqua ammonia and sodium hypochlorite) and dechlorination, through addition of calcium thiosulfate. There is a single chlorine contact tank providing four passes in a serpentine pattern. Each pass is 80 feet in length by 7 feet width with 10 feet water depth. In addition, there is a preliminary rapid mix tank ahead of the chlorine contact tank. The chlorine contact tank has a total volume of 168,000 gallons and a total length-to-width ratio of 46:1.

2.2.1.7 Process Flow Measurement

Process flows are measured using meters at several locations throughout the plant, including the waste mixed liquor, RAS, recycled water, 3W/Binax, 3WLL, and 3WL meters. There is also a sludge meter between the sludge pumps and the digesters. These flow measurements provide a snapshot of flow in a particular process or location.

2.2.1.8 Effluent Flow Measurement

The effluent flow at the LRWRP is currently measured using a Cipoletti weir: a trapezoidal weir with side slopes of approximately 4 vertical to 1 horizontal. Unfortunately, due to the uncertainty of the correction factor involved in the flow equation, Cipoletti weirs are not used where great accuracy is required.

2.2.1.9 Discharge Facilities

Effluent is discharged into San Miguelito Creek approximately 400 yards upstream from its confluence with the Santa Ynez River. During dry months, the combined flow of San Miguelito and the plant effluent are the only flow in the Santa Ynez River downstream from the discharge point.

2.2.2 Solids Handling

The LRWRP includes facilities for screenings removal and handling, primary sludge handling, secondary sludge handling, co-thickening, anaerobic digestion, sludge drying, and sludge storage. Sludge is processed through a gravity thickener, two digesters in series, sludge lagoons and a sand drying bed. Dry biosolids are class A, and after being anaerobically digested, biosolids are air dried within the on-site sludge lagoons. Periodically, the dry biosolids are transported for land application in Kern County.

2.2.2.1 Gravity Sludge Thickener

There is a single gravity sludge thickener that receives raw, primary clarifier sludge, and WAS.

The primary sludge goes through a cyclone-type degritter unit with a classifier before entering the sludge thickener. The grit is subsequently washed and disposed of by landfill.

The degritted primary sludge is then transferred to the gravity thickener. WAS from the secondary clarifiers is also conveyed directly to the gravity thickener. The gravity thickener is a covered, circular concrete tank, 55 feet diameter by 9 feet side wall depth. The tank design

Master Plan Report 14 g:\projects\2000\004649.00\deliverables\master plan report\final\masterplan.doc promotes gravity densification of the combined sludge. The thickened sludge is pumped to the anaerobic digesters.

2.2.2.2 Anaerobic Digester

The anaerobic digester receives sludge from the gravity thickener, which is a combination of both primary and secondary solids. There are two existing duplicate anaerobic sludge digesters, each 55 feet in diameter with 28.5 feet side wall depth. Mixing of digester contents is accomplished through use of digester gas pressurized and pumped to a center draft tube.

Digester covers are of the floating type. The digesters are continuously mixed and heated to 95°F using a system of recirculation pumps and heat exchangers.

Digester gas, primarily methane, is collected and combined with natural gas. The gas is used to fire internal combustion engines that power three blowers. A complex computer-controlled gas management system was installed in 1992 to improve digester operation and energy recovery.

Digester gas can also be flared off.

The solids retention time within the digesters averages 45 days. The digestion process significantly reduces the concentration of volatile suspended solids (VSS). The VSS reduction rate across the digesters was 77 percent for 1999-2001.

2.2.2.3 Sludge Lagoons

Digested sludge is conveyed from the anaerobic digesters to one of two sludge storage lagoons. Make up water is added as necessary to ensure that a liquid layer exits above the sludge to control odors and vectors.

The lagoons are approximately 12 feet deep, each with a design storage of 481,000 ft3. Each lagoon has enough capacity to store two years of digested sludge based on design flow rates.

Lagoon feed is controlled through a system of valves. Level control within the lagoons is achieved with adjustable slide gates that are raised as the solids/liquid level increases and the lagoons are filled. Typically, one lagoon is actively fed with the other lagoon in storage mode.

Ideally, the lagoons are rotated in this manner and fresh digested sludge is not pumped into a lagoon that has been in storage mode for an extended period.

Although not specifically designed to provide treatment, the lagoons act in a facultative manner.

Stabilization of solids stored in the lagoons continues under anaerobic conditions, although at rates much slower than those seen in the optimized environment of the anaerobic digesters.

Regardless, measurable volatile solids reduction and pathogen destruction occurs in the lagoon process. The level of treatment achieved is a function of the length of storage and VSS reduction rates achieved in the lagoons vary accordingly.

A hydraulically powered, submersible, pump is used to remove solids from the sludge lagoons.

The trailer mounted pump is used as a booster pump to transfer the sludge to the drying bed. A flexible suction hose is used and operations staff moves the hose manually to promote solids removal. During pumping, the liquid is preferentially removed and the solids become thicker and thicker. It is generally necessary to add water during the latter stages of the pumping

Master Plan Report 15 g:\projects\2000\004649.00\deliverables\master plan report\final\masterplan.doc process to transfer the sludge. Accordingly, solids concentrations in the lagoon-treated sludge varies during the pumping operation from a few percent solids to well over 10 percent solids.

2.2.2.4 Sand Drying Bed

After settling and detention, the bottom sludge from the lagoons is conveyed to a 4 acre constructed drying bed area for air drying after which the dewatered digested sludge is expected to meet U.S. Environmental Protection Agency (USEPA) requirements, as defined by 40 CFR 503 regulations. During a typical year, the drying bed is filled, dried, and emptied twice, producing approximately 600 to 700 tons of sludge.

The drying process is seasonal, occurring in the dry months between April and November. The City has attempted to use the drying beds year round or further into the rainy season. These efforts were discontinued due to odor generation and vector problems associated with rewetting of material during each rain event.

The drying bed is lined with a mixture of native soil and bentonite clay. A protective rock layer is located above the clay liner, which serves as a drainage layer. A series of perforated pipes collect liquid supernatant from the drying bed and convey it back to headworks by way of the emergency storage lagoon control structure. All underdrainage is by gravity. A layer of sand approximately 6 inches thick is located above the rock layer.

Solids pumped from the storage lagoons enter the drying bed at a single point near the northwest corner. The bed is filled over the course of several days to a prescribed liquid level.

Once filled, solids remain in the drying bed for as long as 3 months, depending on drying conditions. The desired result is a product very low in moisture, typically 85 percent to 90 percent solids.

Biosolids are removed from the drying bed by a private contractor using standard earth moving equipment. They are stockpiled in a dedicated area north of the drying bed. The excavated biosolids generally retain their desiccated, clod-like form (typically, 1 to 4 inches in diameter) and are not pulverized or crushed during the removal process. Once the drying bed has been emptied, additional sand is placed as necessary to provide an even subgrade with sufficient cover over the rock layer.

2.2.2.5 Biosolids Storage

During the drying season, dried biosolids are stored in an uncovered stockpile at the LRWRP at a dedicated location north of the drying bed. On-site storage is necessary as it can take as long as six weeks to receive final results from chemical constituent and pathogen analyses from samples of the final product. On-site storage may also be necessary due to hauler scheduling considerations or other factors, such as weather or site conditions at the land application site.

2.3 Industrial Pretreatment Program

Since the late 1970s, the City has maintained an effective Industrial Pretreatment Program to control industrial and commercial discharges to the sanitary sewer system. This program satisfies the federal pretreatment requirements specified in the City’s NPDES permit and 40 CFR Part 403. The City’s program is routinely audited by Regional Water Quality Control

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Board (RWQCB) and USEPA staff to ensure compliance. Key elements of the City’s pretreatment program include:

● Municipal ordinance sections governing wastewater discharge.

● Technically justified local discharge limits (qualitative concentration based limits).

● Discharge permits issued to industrial users and certain commercial users.

● Discharge permits issued to VAFB dischargers.

● Routine inspections of industrial and commercial facilities.

● Sampling and analysis of industrial and commercial facility discharges.

● Enforcement Response Plan with sufficient enforcement authority.

● Quarterly and annual reporting to regulatory agencies.

The City has relatively few industrial users within its service area. Between 1980 and 1985, there were measured reductions in the concentration of heavy metals in the treatment plant solids, particularly for cadmium and lead. These reductions may be attributed to aggressive pretreatment program controls during that time frame.

Currently, contaminant concentrations in LRWRP influent, effluent, and treated biosolids are relatively consistent and well below national mean values for municipal systems. Regulation of commercial connections, including dry cleaners and restaurants, although not a federal requirement, is part of the City’s pretreatment program. The City will continue to maintain its industrial pretreatment program and make improvements necessary to ensure future compliance.

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Section 3: Regulatory Requirements and Impacts to Plant Facilities

This section summarizes existing state and federal requirements for disposal of the city’s wastewater effluent to the Santa Ynez River. In addition, anticipated future regulatory requirements are discussed. Both existing and future requirements are analyzed against current capabilities of the LRWRP.

3.1 Background

The discharge of all wastewater into waters of the state, including groundwater, is regulated by both state and federal agencies. USEPA has delegated authority to the State Water Resources Control Board (SWRCB) under NPDES for establishing and enforcing waste discharge requirements for all discharges to surface waters of the state. USEPA reserves review and independent enforcement authority.

The SWRCB acts through one of the nine RWQCBs to establish requirements for each discharger. The RWQCBs perform their functions through statutes in the California Administrative Code, the Porter-Cologne Act, as amended. The Central Coast RWQCB (Region 3) has jurisdiction over discharges from the LRWRP. Waste discharge requirements are reviewed by the RWQCB. These waste discharge requirements are incorporated into the NPDES permit. Enforcement of the requirements is under the authority of both the state and federal agencies involved.

The RWQCB is required to prescribe effluent limitations through the NPDES permit as part of the waste discharge requirements of any publicly-owned treatment works (POTW) for the following:

● All substances that the most recent toxic chemical release data reported to the state emergency response commission.

● All substances for which the state board or the regional board has established numeric water quality objectives and has determined that the discharge is or may be discharged at a level which will cause,…