Bruce Lesikar, PhD Texas A & M University University Curriculum Development for Decentralized Wastewater Management

Transcription

1 Chapter 7 Operation and Maintenance Bruce Lesikar, PhD Texas A & M University University Curriculum Development for Decentralized Wastewater Management

2 NDWRCDP Disclaimer This work was supported by the National Decentralized Water Resources Capacity Development Project (NDWRCDP) with funding provided by the U.S. Environmental Protection Agency through a Cooperative Agreement (EPA No. CR ) 0) with Washington University in St. Louis. These materials have not been reviewed by the U.S. Environmental Protection Agency. These materials have been reviewed by representatives of the NDWRCDP. The contents of these materials do not necessarily reflect the views and policies of the NDWRCDP, Washington University, or the U.S. Environmental Protection Agency, nor does the mention of trade names or commercial products constitute their endorsement or recommendation for use.

3 CIDWT/University Disclaimer These materials are the collective effort of individuals from academic, regulatory, and private sectors of the onsite/decentralized wastewater industry. These materials have been peer-reviewed reviewed and represent the current state of knowledge/science in this field. They were developed through a series of writing and review meetings with the goal of formulating a consensus on the materials presented. These materials do not necessarily reflect the views and policies of University of Arkansas, and/or the Consortium of Institutes for Decentralized Wastewater Treatment (CIDWT). The mention of trade names or commercial products does not constitute an endorsement or recommendation for use from these individuals or entities, nor does it constitute criticism for similar ones not mentioned.

4 Citation Lesikar, B.J. and J.C. Converse Subsurface Drip Dispersal: Operation and Maintenance - PowerPoint Presentation. in (M.A. Gross and N.E. Deal, eds.) University Curriculum Development for Decentralized Wastewater Management. National Decentralized Water Resources Capacity Development Project. University of Arkansas, Fayetteville, AR.

5 Subsurface Drip Dispersal System

6 Wastewater Source Monitoring System flow < 70% capacity 70-90% capacity > 90% capacity Monitoring frequency increases as average daily flow increases

7 Flow Metering Determine flow entering the drip system Flow meter Elapsed time meter Cycle/event counter

8 Flow Metering Flow meter Control panels allow recording of critical data. Elapsed time meter Cycle Counter Computer monitoring allows evaluation of loadings to each zone and printing of daily reports. Remote monitoring / Telemetry

9 Pretreatment Components Maintenance requirements for the pretreatment system are dependent upon the type of system. Follow the recommended practices for the pretreatment system.

10 Pump tank Maintenance Check for solids accumulation in the bottom of the tank. Pump tank if necessary. Check water level sensors Remove float tree and check action of floats. Check ultrasonic sensors Remove pump and check inlet screen and foot valve (in suction lift pumps) for accumulation of material

11 Filtration System Maintenance Record information on the control panel (elapsed time readings, number of cycles, etc.) Check operating pressure. Check filtering system - make sure backwash / forward flushing is functional. Clean the filter (media, screen, disk). Check flow rate to zones.

12 Check Dispersal Field Check air relief valves for proper function and no leaks. Check operating pressure in the field to warn about system plugging or leaks. Field flush each zone for removal of fines and slime build-up up in supply lines, supply manifolds, and return manifolds (check with manufacturer regarding drip lines).

13 Dispersal Fields Number of zones Switching valve operational Hydraulic Electrical

14 Monitor Field Zone Flow Rates Compare current flow rates to initial flow rates Reduction in flow rate may indicate a need for chemical/acid treatment of lines.

15 Operation type Field Flushing None, manual, automatic, continuous Operational Flushed Parameters in the field Operating pressure Laterals flushed Zone flushing monitoring Elapsed time meter Cycle counter

16 Excess Flow to Field Zones Check zones receiving excess flow for surfacing water. Evaluate check valves for failure.

17 Drip Filter Maintenance Type of Filter Filter in place Pressure Before and Pressure After Filter Cleaned and replaced Automatic cleaning operational By-pass flow operating Boxes insulated Heater pad operational

18 Drip Filters Types Screen Disc Sand Remove particles greater than 100 microns

19 If the Filter is Gone? Filters protect the emitters Problems for the emitter Effects long term performance of drip distribution system Depends on size of emitters Plugging Inside Outside

20 Vegetation Maintenance Grass cover on the drip field utilizes the nutrients and water. Mowing the field to ensure vigorous growth. No scalping of grass. Reduces growth rate and water removal rate. Trees assist in water removal.

21 Winter Care of Vegetation Over seeding with winter grass. Cold Regions: Leave grass taller in winter to collect snow and reduce wind chill.

22 Check Fields for Surfacing Wastewater Walk the fields to check for surfacing effluent. Repair broken lines as they occur Air relief valves / vacuum breakers with water flowing.

23 Alarms System can have local alarm or remote monitoring of alarms Respond to alarms signaled on a system. Response time depends on system reserve volume above the alarm-on level and simplex or duplex system.

24 Summary Operation, maintenance and monitoring allow continued function of the system. Monitoring zone flow rates and pressures allows early detection of problems. Clean filters. Flush Fields. Monitor air relief valves and wet areas in fields. Respond to alarms.