Occoquan and Dulles Policies Potomac DWSP Partnership Meeting

Occoquan and Dulles Policies Potomac DWSP Partnership Meeting February 21, 2008

An Overview of: • The Occoquan Policy • Occoquan Watershed Monitoring Laboratory (OWML) • Occoquan Non-Point Source Program • Dulles Policy

Special Water Quality Standards in Virginia

Reservoirs and Service Areas

Watershed Facts • • • Area: 592 Square Miles Streams: 1, 300 Miles Major impoundments: – – – Lake Manassas Lake Jackson Occoquan Reservoir • Land Use (estimate): – – – – 14% Low Density Residential 8% Medium and High Density Residential 4% Commercial and Industrial 1% Institutional 13% Agricultural 9% Pasture 51% Forest and Idle • Residents: 390, 000 (estimate) Source: OWML -1998, NVRC - 2000, 2005

The Problem • Late 1960 s – WQ problems in the Occoquan Reservoir: – – – Massive algal blooms Periodic episodes of taste and odors in drinking water Shortened filter runs due to clogging during periods of high algal growth – Periodic fish kills due to oxygen depletion – Hypolimnetic de-oxygenation due to accumulation of organic material in the sediments • The State Water Control Board (Board) commissioned a Study to recommend a course of action to preserve the Occoquan as a valuable water resource for future generations. • The Study results stated that point source pollution was the primary cause of water quality degradation • A high degree of waste treatment would be necessary to prolong the life of the drinking water supply.

Summer 1973 – Algal Bloom (Source: OWML)

The Policy 1 1 A Policy for Waste Treatment and Water Quality Management in the Occoquan Watershed • Formed UOSA (Upper Occoquan Sewage Authority) to Consolidate Older WWTPs • Established Occoquan Watershed Monitoring Program • Established Indirect Potable Reuse as Sustainable Water Supply for Northern Virginia • Regulation administered by Virginia Department of Environmental Quality (VDEQ)

Policy Requirements – WWTP Plants • Preferably only two high-performance regional plants • All point sources preferably 20 stream miles from Fairfax • • Water intake Incremental increases in regional plant capacity must be approved based on results of the monitoring program All future plants must meet or exceed UOSA design standards

Policy Requirement - Effluent • Discharge Limits: – COD (mg/l) - 10. 0 – Suspended solids (mg/l) - 1. 0 – Nitrogen (mg/l) - 1. 0 (as TKN) – Phosphorus (mg/l) - 0. 1 – MBAS (mg/l) - 0. 1 – Turbidity (NTU) - 0. 5 – Coliform per 100 ml Sample - less than 2. 0

UOSA Process Treatment (from OWML)

Policy Requirement – Wastewater Operation All pumping stations in the watershed must have: – – – – Stand-by pumping units At least one “on-site” back-up power supply At least one “off-site” back-up power supply Be designed so that no single failure of a mechanical or electrical component could degrade pumping capability Have pumps and valves arranges so that these units can be removed and replaced without by-pass pumping Have retention basins of minimum one-day capacity Have flow measurement devices • Nitrate removal required when NOx conc. Reach 5 mg/l at Intake

Policy Requirement – Collection Systems • Certified and submitted to Board – Inflow/Infiltration (I/I) limited to 100 gal/inchdia/mile/day • Approved pre-treatment program • Up-to-date and maintained (subject to annual inspection) electrical and fluid system diagrams • Detailed as-built and installed drawings

Occoquan Watershed Monitoring Program • Occoquan Watershed Monitoring • • Lab (OWML) – Sampling and Analysis – Stream Gages and Reservoir Stations Overseen by Occoquan Watershed Monitoring Subcommittee Objective: to Ensure that performance levels are maintained and that the effects of point and non-point sources are known

Occoquan NPS Programs • Technical Investigations and Support – – – Northern Virginia BMP Handbook Nonstructural Urban BMP Handbook Land Use Inventory and Updates • Fairfax County Water Supply Overlay District • Historic Fairfax County Down-zoning to • Protect Occoquan Reservoir Occoquan NPS Model

Summary • Occoquan Policy was a milestone in Water Quality Management in the Commonwealth of Virginia • Water Quality improved dramatically after UOSA came on-line • Reservoir Water Quality has remained stable for decades

Special Water Quality Standards in Virginia SWCB Adopts in 1975 (revised in 2004) LCSA Broad Run WRF on-line soon SWCB Adopts in 1971 (revised 1981 and 1991) UOSA on-line in 1978

Evolution of Dulles Policy • Wastewater issues of 1970 s • Adopted by SWCB in 1975 as a ‘planning’ document for regional sewage treatment in northwestern Fairfax and eastern Loudoun Counties • Policy revised in 2004 to update for new LCSA Water Reclamation facility

Dulles Policy – Regional Plants • Limits Regional Plants to 2 • Discharge in the Broad Run and Goose Creek • • Watersheds No discharges within 10 stream miles upstream from Water Supply Intakes High-performance effluent requirements based on Occoquan Policy Nitrate removal required when NOx conc. reach 5 mg/l at Intake LCSA and Fairfax Water to coordinate monitoring program

Collaborative Updates (2000 -2004) • DAWP Stakeholder Meetings: FW, LCSA, Fairfax Co. , VDEQ, OWML, VDH, NVRC, City of Leesburg • Craft reasonable and protective Policy modifications • Objective: Ensure Protection of FW Intake

Dulles Policy Revisions (2004) • Effluent Quality Limits for COD, TKN, TP, Turbidity, Coliform (now E. Coli limit), and TSS – same as Occoquan Policy • Collaborative process was successful

Questions?