Wastewater Facility Plan (Sprenkle & Associates 2001) 2
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January 14, 2016 Mr. Steve Walensky Director of Public Works City of Cassville 300 Main Street Cassville, Missouri 65625 Re: WASTEWATER COLLECTION SYSTEM FACILITY PLAN OA PROJECT NO. 014-2994 Dear Mr. Walensky, We present herewith a copy of the City of Cassville Wastewater Collection System Facility Plan, in accordance with our agreement dated July 31, 2014. This Facility Plan summarizes our evaluation of the City’s existing wastewater collection system with respect to the development of a comprehensive plan to guide collection system improvements to be pursued by the City over the next several years. Two copies of this report will be sent to MoDNR as part of the Small Community Engineering Assistance Grant requirements. We appreciate all of the assistance received from officials and employees of the City during the preparation of this Facility Plan. Sincerely, OLSSON ASSOCIATES Jerry Jesky, P.E. Senior Engineer Attachment 550 St. Louis Street TEL 417.890.8802 www.olssonassociates.com Springfield, MO 65806 FAX 417.890.8805 TABLE OF CONTENTS Page I. INTRODUCTION ............................................................................................................. 1 A. Purpose .................................................................................................................... 1 B. Scope ....................................................................................................................... 1 C. Existing Conditions ................................................................................................... 1 D. Previous Wastewater System Documentation .......................................................... 3 II. GENERAL INFORMATION AND PLANNING AREA ....................................................... 4 A. Identification ............................................................................................................. 4 B. Planning Area ........................................................................................................... 4 C. Topographic, Geological, Soil, and Climate Characteristics of Planning Area ........... 4 III. PLANNING PERIOD AND POPULATION PROJECTION ................................................ 6 A. Planning Period ........................................................................................................ 6 B. Population Projection ................................................................................................ 6 IV. EXISTING FACILITIES ANALYSIS ................................................................................. 9 A. Existing Collection System ....................................................................................... 9 B. Existing Wastewater Treatment Plant (WWTP)....................................................... 12 V. HYDRAULIC CAPACITY EVALUATION ........................................................................ 13 A. Water Use and Wastewater Treatment Facility Flow Monitoring ............................. 13 B. Wet Weather Flow Projections versus Hydraulic Capacity ...................................... 25 VI. RECENT CCTV EFFORTS AND IDENTIFIED PROBLEM AREAS ............................... 27 A. General .................................................................................................................. 27 B. Observed Collection System Defects ...................................................................... 27 VII. PROJECT ALTERNATIVE ANALYSIS .......................................................................... 30 A. Repair Alternatives ................................................................................................. 30 B. Gravity Main Lines .................................................................................................. 32 C. Service Line Connections ....................................................................................... 33 D. Manholes ................................................................................................................ 34 VIII. RECOMMENDED PROJECT ALTERNATIVE SUMMARY AND JUSTIFICATION ........ 35 A. Recommended Rehabilitation Alternatives (Years 1-5) ........................................... 35 B. Private Inflow and Infiltration Abatement (Years 6-10) ........................................... 36 C. Cost Opinion for Proposed Rehabilitation ............................................................... 37 D. Funding Strategy and Impact on User Fees ............................................................ 39 E. Proposed Rehabilitation Schedule .......................................................................... 39 F. Conclusion.............................................................................................................. 40 Project 014-2994 i January 2016 Tables Table III-1 Historical Population Data .................................................................................... 7 Table III-2 Projected Population Data ................................................................................... 8 Table IV-1 Sanitary Collection System Inventory ................................................................... 9 Table V-1 Estimated Population versus Water Data for 2010 to 2014 ................................ 13 Table V-2 Recent Summary of WWTP Effluent Flows and Area Precipitation .................... 14 Table V-3 Dry Weather WWTP Effluent Flows ................................................................... 16 Table V-4 Average Daily Dry Weather Wastewater Effluent per Person ............................. 17 Table V-5 Well Water Use & WWTP Outfall Comparison from 2010 to 2014 ..................... 18 Table V-6 WWTP Daily Influent and Effluent Flow Data for May 9th – July 23rd, 2015 ......... 20 Table V-7 Flow Data per Capita Comparison ..................................................................... 24 Table V-8 Projected WWTP Influent Flow Ranges Based on Dry and Wet Weather per Capita Projections .............................................................................................. 25 Table V-9 Needed Wet Weather Flow Reductions Over the Planning Period ..................... 26 Table VII-1 Sewer Line Inventory for Saturation Zone and Outer Zone ................................ 33 Table VII-2 Saturation & Outer Zone Manhole Inventory ...................................................... 34 Table VIII-1 Opinion of Probable Construction Costs for Recommended Improvements ....... 38 Table VIII-2 City of Cassville Current Sewer User Rate Schedule ......................................... 39 Figures Figure III-1 Historic and Projected Population ........................................................................ 8 Figure V-1 Cassville Well Water Pumped, WWTP Flows, & Rainfall .................................... 23 Exhibits Exhibit 1 Wastewater System Layout Map Exhibit 2 Wastewater System Basin Map Exhibit 3 Wastewater System Saturation Zone Map Appendices Appendix A CCTV Review Spreadsheet Project 014-2994 ii January 2016 City of Cassville, Missouri Wastewater Collection System Facility Plan I. INTRODUCTION A. Purpose The purpose of this facility plan is to develop a comprehensive Collection System Evaluation to guide sewer collection system improvements to be pursued by the City of Cassville over the next several years. This facility plan presents an analysis and evaluation of previous wastewater system reports and smoke-testing results, recent sewer line videoing and flow monitoring, Public Works Department maintenance logs, geographical information system (GIS) mapping, and a funding strategy to prioritize and schedule the recommended actions stemming from the evaluation. B. Scope Preparation of this facility plan included the following steps: 1. Review of the City’s previous wastewater system reports; 2. Review of the City’s sewer system GIS mapping; 3. Review of previous smoke testing results; 4. Review and analysis of recent closed-caption television (CCTV) sewer line videos; 5. Review of recent Public Works Department maintenance logs and activities; 6. Review of City pump station information; 7. Discussion of sewer system issues with Public Works staff, including coordinating additional inspections; 8. Development of a prioritized spreadsheet of recommended improvements based on the review, analysis, and evaluation of the data; 9. Development of cost opinions and a funding strategy for the City to complete the recommended improvements and actions over the next several years. C. Existing Conditions The City of Cassville’s existing wastewater system consists of a mostly gravity-flow collection system with only one lift station that serves a very small area of the system, and a mechanical wastewater treatment plant (WWTP) with an adjacent overflow lagoon for wet-weather flow storage. The collection system consists of approximately 171,325 feet of gravity mains, 640 manholes, 34 lampholes, and 953 feet of force main from one lift station in the northern portion of the system. The gravity sewer mains range in size from 6” to 24” in diameter. Project No. 014-2994 1 January 2016 City of Cassville, Missouri Wastewater Collection System Facility Plan A significant portion of the gravity lines are 8-inch vitrified clay pipe (VCP). Much of the original collection system was constructed prior to 1940, with portions of the original system still in use today. Newer lines have been constructed with conventional polyvinyl chloride (PVC) pipe. The older manholes were constructed with brick and mortar,