SGQM 2

• Prevention


  Applying measures to prevent pollutants from being discharged into the environment or ensure their concentrations are within standard limits
• Measures for prevention


  • Restrict land use
  • Monitor ambient groundwater quality regularly
  • Participation of industries
  • Regulate and minimize use of potential contaminants
  • Require protective engineering works
  • Adopt good engineering practices
  • Monitor underground storage tanks/pipes
  • Participation of community
• Practices to reduce contamination

  • Minimize use of household chemicals containing Hazardous substances
  • Avoid draining chemicals, motor oil, insecticides in community areas
  • Reduce pesticide application
  • Use proper procedures for handling chemicals (Paints, Pesticides, Insecticides, polishing materials, cleaning chemicals and detergents)
  • Immediately clean any spills and report any leakages to concerned department
• Groundwater sampling is done for a variety of purposes, including meeting regulatory requirements; waste disposal site monitoring; ambient groundwater quality monitoring; research; and general bacteriological and chemical quality monitoring
• Several analyses must be made in the field at the time of sampling
• For parameters that are needed to be measured in the laboratory, special care must be taken not to contaminate samples
• Documentation of field sampling is done in a bound logbook
• Groundwater Quality Guidelines


  Refer to DAO 2021-19 for updated Water Quality Guidelines and General Effluent Standards
• Rule of thumb when constructing pumping wells: Septic Tank & Water Table
• Remediation


  The cleanup or other methods used to remove or contain a toxic spill or hazardous materials from a contaminated site
• Purpose of remediation


  To restore contaminated groundwater to its original quality or at least acceptable quality
• Remediation is about safety
• 3 major types of remedial actions

  • Containment – prevent the pollutants in the soil or groundwater from spreading
  • Removal – contaminated soil and/or pollutants
  • Treatment - contaminated soil and/or pollutants
• Considerations for remediation


  • What are the materials on the ground?
  • How much chemical concentration is there?
  • How did the contaminants get in the site?
  • Is the source still present and adding to the pollution?
  • How deep is the groundwater table?
  • Type of soil, groundwater flow direction etc.
  • How long is the clean-up, days, years?
  • Is there immediate need to remediate the site or there is less risk to people/organisms? (e.g. presence of drinking well nearby)
• Slurry Wall


  • Subsurface barriers that impede or stop groundwater flow
  • Consist of a mixture of soil, bentonite clay, and water, poured into trenches as a "slurry"
  • Used to contain contaminated groundwater, divert uncontaminated groundwater flow, and/or provide barriers for groundwater treatment systems
  • Works with loose soil
• Configurations of keyed-in slurry walls

  • Total enclosure
  • Upgradient partial barrier
  • Downgradient partial barrier
• Sheet Piling


  • Large sheets of iron driven into the ground
  • Have essentially zero permeability and are generally of low reactivity
  • Can leak because it is difficult to obtain a perfect seals between individual sheets
  • Also used in construction activities
• Hydraulic Barriers


  • Based on manipulation of water pressures
  • Generated by the pressure differentials arising from the extraction of injection of water using wells or drains
  • Has the capacity to capture the CONTAMINANT PLUME, limiting the spread of the contamination
  • Number of installed wells depends on the extent of contamination
• Excavation of contaminated soil


  • A very common and widely used method for removing contaminated materials
  • Disadvantages: Exposure of site workers to hazardous chemicals, Treatment and/or disposal of contaminated soil is usually expensive, Feasible for small and shallow areas only
• Pump and treat


  • The most widely used remediation technique for contaminated groundwater
  • One or more extraction wells are used to remove contaminated water from the subsurface
  • Clean water brought into the contaminated region by the flow associated with pumping removes, or "flushes", additional contaminants
• Contaminant plume capture


  • Injection of water using wells or drains
  • Limits the spread of contamination
• Number of installed wells

  Depends on the extent of contamination
• Excavation of contaminated soil


  A very common and widely used method for removing contaminated materials
• Pump and treat


  1. Pump-and-treat is the most widely used remediation technique for contaminated groundwater

  2. One or more extraction wells are used to remove contaminated water from the subsurface

  3. Clean water brought into the contaminated region by the flow associated with pumping removes, or "flushes", additional contamination by inducing desorption from the porous-media grains and dissolution of NAPL (Non-aqueous phase liquids)

  4. The contaminated water pumped from the subsurface is directed to some type of treatment operation, which may consist of air stripping, carbon adsorption, or aboveground biological treatment system
• Soil Vapor Extraction (SVE) (Air Sparging)


  1. A fluid (air) is pumped through a contaminated domain to enhance contaminant removal

  2. The subsurface must contain a gas phase through which the contaminated air can travel

  3. Contaminants must be capable of transfer from other phases (solid, water, immiscible liquid) to the gas phase
• Contaminants suitable for SVE

  • Chlorinated solvents (trichloroethene, tetrachloroethene)
  • Certain components of fuels (benzene, toluene)
• Chemical Remediation


  Chemical oxidation by pumping chemicals/oxidants such as hydrogen peroxide and potassium permanganate
• Bioremediation


  Any process that uses microorganisms, fungi, green plants or their enzymes to return the natural environment altered by contaminants to its original condition
• Bioremediation


  • Low-cost, low tech
  • Microbes living in the soil eat the harmful chemicals, less harmful, harmless material
  • Focus on how we will improve the condition/take care of the contaminated site
  • Can be more effective by manipulating the environmental parameters
• Bioventing


  Supplying air and nutrients to soil to stimulate indigenous bacteria
• Bioventing


  • Most common type of bioremediation
  • Low air flow rates to provide only enough oxygen to sustain microbial activity
• In-situ Biodegradation


  Involves supplying oxygen and nutrients by circulating aqueous solutions to stimulate naturally occurring bacteria to degrade organic contaminants
• Biosparging


  Involves the injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria
• Bioaugmentation


  Involves the addition of microorganisms indigenous or exogenous to the contaminated sites
• Landfarming


  Aerobic decomposition – done through plowing; is a simple technique in which contaminated soil is excavated and spread over a prepared bed and periodically tilled until pollutants are degraded
• Composting


  Combine contaminated soil with manure, food waste and agricultural waste
• Biopiles


  1. Engineered cells are constructed as aerated composted piles

  2. Hybrid landfarming to make degradation faster
• Biopiles


  • Also known as biocells, bioheaps, biomounds, and compost piles
  • Used to reduce concentrations of petroleum constituents in excavated soils through the use of biodegradation
  • Involves heaping contaminated soils into piles (or "cells") and stimulating microbial activity within the soils through the aeration and/or addition of minerals, nutrients, and moisture
  • Similar to landfarms – both are above-ground, engineered systems that use oxygen, generally from air, to stimulate the growth and reproduction of aerobic bacteria which, in turn, degrade the petroleum constituents absorbed to soil
• Bioreactors


  Processing of contaminated solid material (soil, sediment, sludge) or water through an engineered containment system (controlled parameters)
• Advantages of Bioremediation


  • Natural process - therefore perceived by the public as an acceptable waste treatment process for contaminated material such as soil
  • Complete destruction of a wide variety of contaminants
  • Instead of transferring contaminants from one environmental medium to another, the complete destruction of target pollutants is possible
  • Eliminates the need to transport quantities of waste off site and the potential threats to human health and the environment that can arise during transportation
  • Low cost