Alan L. Horton Wastewater Treatment Plant

1. Alan L. Horton Wastewater Treatment Plant A Tour of the Plant Prepared by MSWD Updated July 2009

2. Benefits to Community Sewer and wastewater treatment vs. individual septic tanks • Sewer system and wastewater treatment protect our precious groundwater from potential contamination by septic tanks. • “Septic systems are second greatest threat to groundwater quality (as viewed by State water quality agencies).” - from EPA’s “Decentralized Wastewater Treatment Systems: A Program Strategy” • Sewers collect wastewater and convey it to the plant, where it is treated. • Treated water is percolated back into the ground.

3. Overview of Treatment Process • Sewage flows to plant for treatment. • The sewage is aerated, mixed and concentrated. Naturally occurring microorganisms digest the waste. • Secondary effluent is percolated back into the ground. • Solids are dewatered and hauled away to landfills, compost sites or applied directly to the land as fertilizer.

4. Through The Plant Step By Step

5. Pump Station • Receives and lifts the raw sewage into the treatment process. • Currently designed to handle 2 MGD flow. • Employs two 33.5 HP and two 12 HP pumps

6. Channel Grinder • Rotating screens channel debris into two cutter stacks. • Debris may be organic or inorganic waste. • Cutter stacks chew up large floating debris.

7. Vortex Grit Removal • Grit has no use in the biological process and must be removed. Grit includes sand, gravel and other heavy, inorganic materials. • Rotating paddles create a vortex causing the grit to drop to the bottom. • Grit drops into a sump and is pumped to the grit classifiers for dewatering and disposal.

8. Grit Classifiers • Grit Classifiers separate water from the grit, then drop the solids into a dumpster. • The dumpster is hauled to a landfill weekly.

9. Aeration Basins • After grit removal, the head works splitter box delivers the influent to the relevant aeration basins. • The sewage is mixed and aerated in the aeration basins. • Oxygen is required for aerobic bacteria to digest the waste.

10. Aerators • Our 2 largest aeration basins hold 750,000 gallons each. • Our largest two-speed aerators run at 56 to 75 HP. Aerator Driver

11. Clarifiers • The clarifiers separate the solids from the water. The settled solids are returned to the head works to undergo further treatment. • Solids are routinely removed for disposal. • Our 2 largest clarifiers are 55 ft. in diameter and 14 ft. deep.

12. Percolation Ponds • Effluent from the secondary clarifiers gravity flow to the percolation ponds. • Here it percolates through a natural filtering process before returning to the water table.

13. Percolation Ponds • The effluent is also used on-site for equipment wash downs and landscape irrigation. • Reclaiming this water for golf course and other irrigation uses would require further treatment.

14. Belt Filter Press • Sludge is dewatered on a “belt filter press,” which squeezes the water out of the sludge. • The dewatered solids are loaded into a trailer. • The trailers are covered & hauled away when filled. • The liquid filtrate is returned to the treatment process head works.

15. Controls & Electric Supply • The Treatment plant controls are managed in the electrical room. • Uninterrupted power is assured by a standby generator.

16. Standby Generator • This 1502 HP diesel engine provides backup electricity. • Engine weighs over 21,000 lbs.

17. Alan L. Horton Wastewater Treatment Plant - History • Expansion 4 in October 2002 increased capacity from 1 million gallons per day (MGD) to 2 MGD. • Expansion potential to 5 MGD. • Achieved without additional bond debt.

18. Alan L. Horton Wastewater Treatment Plant - On the Horizon • Expansion 5 is in the final design stage and is expected to be completed in 2010, at a cost of approximately $10-14 million. • A permanent belt press dewatering system is included in the expansion plans. • Expansion 5 will increase plant capacity to 3MGD

19. Alan L. Horton Wastewater Treatment Plant - Industry • HWTP has won numerous prestigious industry awards: • 2008 Plant of the Year (less than 5MGD category) • 2008 Collection System of the Year (0-249 miles category) • 2007 Operator of the Year (Chris Jacobson, Operator) • 2006 Plant of the Year (less than 5MGD category) • 2006 Collections System of the Year (0-249 miles category) • 2006 Supervisor of the Year (Wayne Robertson, Chief Plant Operator) • 2006 Collection System Person of the Year (Lee Boyer, Lead Operator) • The awards were presented by the Colorado River Basin Section (CORBS) of the California Water Environment Association (CWEA).

20. Alan L. Horton Wastewater Treatment Plant - Community • MSWD partners with community and education groups, such as this middle school Earth Sciences class which toured the plant during a school field trip organized by the Desert Hot Springs Groundwater Guardian team. • MSWD participates in local school and community science fairs and career days events, highlighting the broad range of careers available in the water industry and encouraging young people to take an interest in environmental sciences.