WASTEWATER TREATMENT PLANT UPGRADE PROJECT

PRELIMINARY ENGINEERING REPORT & SITE APPLICATION

(AMENDMENT OF AN EXISTING SITE APPLICATION)

Mountain Water & Sanitation District 12365 Highway 285 Conifer, CO 80433

NPDES# CO-0022730

Unincorporated Jefferson County, Colorado

MARCH 2012

BY:

AQUAWORKS DBO, INC. 5325 SOUTH VALENTIA WAY

GREENWOOD VILLAGE, CO 80111

AWDBO5P.E. 3/29/12

TABLE OF CONTENTS

Mountain Water & Sanitation District Preliminary Engineering Report Wastewater Treatment Improvements i AquaWorks DBO, Inc.

EXECUTIVE SUMMARY .....................................................................................................................4 PLANNING CONDITIONS ...................................................................................................................5 2.1 Planning Area.......................................................................................................................5 2.1.1 Overview ..............................................................................................................................5 2.1.2 Geography & Climate ..........................................................................................................5 2.1.3 WWTP Site ..........................................................................................................................6 2.1.4 Existing Site Application and Discharge Permit .................................................................6 2.1.5 PELS ....................................................................................................................................6 2.2 208 Plan Coordination .........................................................................................................7 2.3 Growth Areas and Population Trends ..................................................................................8 2.4 Wastewater Flow Forecasts .................................................................................................8 2.5 Wasteload Forecasts...........................................................................................................10 2.6 Summary of Proposed Capacity and Forecasted Loading .................................................11 DESCRIPTION OF EXISTING FACILITIES .........................................................................................12 3.1 Service Area Features ........................................................................................................12 3.2 Area Discharge Permits .....................................................................................................12 3.3 Facilities Layout and Description ......................................................................................12 3.4 Wastewater Flows ..............................................................................................................13 3.5 Financial Status and Users .................................................................................................13 4.1 Compliance ........................................................................................................................15 4.2 Security ..............................................................................................................................15 4.3 Operation and Maintenance ...............................................................................................15 4.4 Growth ...............................................................................................................................15 ASSESSMENT OF ALTERNATIVES .................................................................................................16 No Action .......................................................................................................................................16 Optimizing Existing Facilities .......................................................................................................16 Interconnecting to Nearby Facilities ..............................................................................................17 Upgrade with a New Facility .........................................................................................................17 5.1 Description .........................................................................................................................17 5.1.1 Membrane Biological Reactor ...........................................................................................18 5.1.2 Sequencing Batch Reactor .................................................................................................23 5.1.3 Conventional Activated Sludge .........................................................................................29 5.2 Design Criteria ...................................................................................................................32 5.3 Environmental Impacts ......................................................................................................32 5.4 Land Requirements ............................................................................................................33 5.5 Construction Issues ............................................................................................................33 5.6 Operational Aspects ...........................................................................................................34 5.7 Cost Estimates ....................................................................................................................35 5.8 Advantages/Disadvantages ................................................................................................35 5.9 Summary of Alternatives ...................................................................................................36 SELECTED ALTERNATIVE ..............................................................................................................38 6.1 Justification of Selected Alternative ..................................................................................38

TABLE OF CONTENTS

Mountain Water & Sanitation District Preliminary Engineering Report Wastewater Treatment Improvements ii AquaWorks DBO, Inc.

6.2 Technical Description ........................................................................................................39 6.3 Environmental Review of Selected Alternative .................................................................43 6.4 Green Project Reserve........................................................................................................43 6.4.1 Introduction ........................................................................................................................43 6.4.2 Component #1: Install WWTP Energy Efficient Process Equipment ...............................44 6.4.3 Component #2: Anaerobic Sludge Digestion ....................................................................46 6.4.4 Green Project Reserve Conclusion ....................................................................................48 6.5 Project Costs ......................................................................................................................49 6.6 Project Implementation ......................................................................................................51 6.7 Preliminary Effluent Limits Application and Site Application .........................................51 6.8 Process Design ...................................................................................................................52 6.9 Final Design .......................................................................................................................52 6.10 Discharge Permit ................................................................................................................52 6.11 Miscellaneous Permits .......................................................................................................52 ABBREVIATIONS ............................................................................................................................53 TABLES Table 1. Preliminary Effluent Limits .............................................................................................. 7 Table 2. Population Growth Estimate ............................................................................................. 8 Table 3. Wastewater Flow Forecasts .............................................................................................. 8 Table 4. Waste-load Forecasts ...................................................................................................... 10 Table 5. Design Capacity Summary Table ................................................................................... 11 Table 6. Cost Estimates for Alternatives ...................................................................................... 35 Table 7. MBR Advantages/Disadvantages ................................................................................... 35 Table 8. SBR Advantages/Disadvantages..................................................................................... 35 Table 9. Conventional Activated Sludge Advantages/Disadvantages .......................................... 36 Table 10. Summary of Alternatives .............................................................................................. 37 Table 11. Component Summary ................................................................................................... 43 Table 12. Project Components ...................................................................................................... 44 Table 13. Current WWTP Power Consumption ....................................