Snoqualmie Pass Utility District
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FACT SHEET FOR STATE WASTE DISCHARGE PERMIT NO. ST-9005 SNOQUALMIE PASS UTILITY DISTRICT DATE OF THIS FACT SHEET - MAY 5, 2006 DATE OF EXPIRING PERMIT - JUNE 30, 2011 SUMMARY The Snoqualmie Pass Utility District (SPUD) is seeking re-issuance of its State Waste Discharge Permit. This utility district operates both water delivery and wastewater treatment for commercial businesses and private residences in an area encompassing portions of western Kittitas and eastern King Counties at Snoqualmie Pass, along Interstate Highway 90, at Snoqualmie Pass. This region's climate is characterized by abundant precipitation, a large portion of which falls as snow and rain from November through April. The economy at Snoqualmie Pass is largely recreationally based, with winter-time skiing predominating. The Summit At Snoqualmie operates four separate ski areas, with the skier visitation rate averaging 3,700 per day. The visitation rate exhibits a large variation, ranging from 150 to 10,000 visitors per day. The District's wastewater treatment facilities consist of the collection system, a two-cell partially aerated lagoon system, effluent disinfection with chlorination, and sprayfield land treatment. The sprayfield is located on a forested hillside, under a Special Use Permit issued by the United States Forest Service. The influent flow volume in the fall, winter, and spring is approximately double the volume in the summer months. The large winter-time influent flow rates necessitate the utilization of the sprayfield in the winter-time because the lagoon's storage volume is not sufficient to hold the winter-time wastewater. Typically, the Department of Ecology (Department) only permits sprayfield land treatment of wastewater during the summer growing season, when the vegetation and soil microbiology nutrient uptake is at its optimum. Since winter-time biological activity in the soil profile is significantly reduced, the application of wastewater during the winter at Snoqualmie Pass has the potential to violate ground and surface water standards. Therefore, the proposed permit requires the Permittee to complete a Water Quality Monitoring Project. The Water Quality Monitoring Project may reveal that effluent discharged to the sprayfield violates, or has the potential to violate Surface Water Quality Standards. In that case, the following wastewater discharge permit issued five years hence, may be a National Pollution Discharge Elimination System (NPDES) permit and/or more monitoring studies may be required. FACT SHEET FOR SNOQUALMIE PASS UTILITY DISTRICT STATE PERMIT NO. ST-9005 Page 2 of 36 EXPIRATION DATE: JUNE 30, 2011 TABLE OF CONTENTS Page SUMMARY.................................................................................................................................... 1 INTRODUCTION .......................................................................................................................... 4 GENERAL INFORMATION......................................................................................................... 5 BACKGROUND INFORMATION ............................................................................................... 5 DESCRIPTION OF THE COLLECTION AND TREATMENT SYSTEM.............................. 5 History ..................................................................................................................................... 5 USFS Special Use Permit ........................................................................................................ 6 Collection System Status ......................................................................................................... 7 Treatment Processes ................................................................................................................ 7 Sprayfield Distribution System................................................................................................ 8 Residual Solids ........................................................................................................................ 9 GROUND WATER ....................................................................................................................9 PERMIT STATUS...................................................................................................................... 9 SUMMARY OF COMPLIANCE WITH THE PREVIOUS PERMIT ...................................... 9 WASTEWATER CHARACTERIZATION............................................................................. 10 SEPA COMPLIANCE.............................................................................................................. 11 PROPOSED PERMIT LIMITATIONS........................................................................................ 12 TECHNOLOGY-BASED EFFLUENT LIMITATIONS......................................................... 12 GROUND WATER QUALITY-BASED EFFLUENT LIMITATIONS ................................. 13 Antidegradation of Ground Water......................................................................................... 15 WATER QUALITY-BASED EFFLUENT LIMITATIONS ................................................... 15 Antidegradation of Surface Waters ....................................................................................... 16 COMPARISON OF LIMITATIONS WITH THE EXISTING PERMIT ISSUED SEPTEMBER 1982 .......................................................................................................... 16 MONITORING REQUIREMENTS............................................................................................. 17 INFLUENT AND EFFLUENT MONITORING ..................................................................... 17 WATER QUALITY MONITORING PROJECT..................................................................... 17 LAB ACCREDITATION......................................................................................................... 20 OTHER PERMIT CONDITIONS ................................................................................................ 20 REPORTING AND RECORDKEEPING................................................................................ 20 FACILITY LOADING............................................................................................................. 20 OPERATIONS AND MAINTENANCE.................................................................................. 21 RESIDUAL SOLIDS HANDLING.......................................................................................... 21 PRETREATMENT................................................................................................................... 22 AS-BUILT DRAWINGS.......................................................................................................... 22 FACT SHEET FOR SNOQUALMIE PASS UTILITY DISTRICT STATE PERMIT NO. ST-9005 Page 3 of 36 EXPIRATION DATE: JUNE 30, 2011 GENERAL CONDITIONS ...................................................................................................... 22 RECOMMENDATION FOR PERMIT ISSUANCE ................................................................... 23 REFERENCES FOR TEXT AND APPENDICES....................................................................... 23 APPENDIX A--PUBLIC INVOLVEMENT INFORMATION................................................... 24 APPENDIX B--GLOSSARY ....................................................................................................... 25 APPENDIX C--TECHNICAL CALCULATIONS ...................................................................... 29 APPENDIX D--RESPONSE TO COMMENTS .......................................................................... 36 FACT SHEET FOR SNOQUALMIE PASS UTILITY DISTRICT STATE PERMIT NO. ST-9005 Page 4 of 36 EXPIRATION DATE: JUNE 30, 2011 INTRODUCTION This fact sheet is a companion document to the draft State Waste Discharge Permit No. ST-9005. The Department of Ecology (the Department) is proposing to issue this permit, which will allow discharge of wastewater to waters of the State of Washington. This fact sheet explains the nature of the proposed discharge, the Department's decisions on limiting the pollutants in the wastewater, and the regulatory and technical bases for those decisions. Washington State law (RCW 90.48.080 and 90.48.162) requires that a permit be issued before discharge of wastewater to waters of the state is allowed. Regulations adopted by the State include procedures for issuing permits (Chapter 173-216 WAC), technical criteria for discharges from municipal wastewater treatment facilities (Chapter 173-221 WAC) and water quality criteria for ground waters (Chapter 173-200 WAC). They also establish the basis for effluent limitations and other requirements which are to be included in the permit. This fact sheet and draft permit are available for review by interested persons as described in Appendix A--Public Involvement Information. The fact sheet and draft permit have been reviewed by the Office of Environmental Health & Safety of the Washington State Department of Health and by the Permittee. Errors and omissions identified in these reviews have been corrected before going to public notice. After the public comment period has closed, the Department will summarize the substantive comments and the response to each comment. The summary and response to comments will become part of the file on the permit and parties submitting comments will receive a copy of the Department's response. The fact sheet will not be revised. Changes to the permit will