Chapter: A buyer is purchasing a property in Hawaii with a septic system. What should the buyer's agent advise the buyer to do during the inspection period? (EN)

Chapter: A buyer is purchasing a property in Hawaii with a septic system. What should the buyer’s agent advise the buyer to do during the inspection period?

Understanding Septic Systems: A Scientific Overview

A septic system, also known as an On-Site Sewage Disposal System (OSDS), is a decentralized wastewater treatment system commonly used in areas lacking connection to a municipal sewer system. In Hawaii, given the diverse geographical landscape and varying population densities, septic systems are prevalent. Proper functioning relies on a complex interplay of biological, chemical, and physical processes.

1. System Components and Processes:

• Septic Tank: The initial treatment stage, where solids settle out and anaerobic digestion begins. Wastewater entering the tank separates into three layers:
  • Scum Layer: Floating solids like fats, oils, and grease (FOG).
  • Effluent Layer: The relatively clarified liquid in the middle.
  • Sludge Layer: Settled solids at the bottom, composed of organic matter and inorganic sediments.
• Drainfield (Leach Field): A series of underground trenches or beds where effluent is discharged for further treatment and dispersal into the soil. The soil acts as a natural filter, removing pathogens, nutrients, and remaining organic matter.

2. Biological Processes:

• Anaerobic Digestion: Occurs primarily in the septic tank. Anaerobic bacteria break down organic matter in the absence of oxygen. This process reduces the volume of sludge and produces biogas, primarily methane (CH₄) and carbon dioxide (CO₂).
  • Simplified Reaction: (CH₂O)_n → n/2 CO₂ + n/2 CH₄ (where (CH₂O)_n represents complex organic matter).
• Aerobic Treatment: Predominantly in the drainfield. Aerobic bacteria utilize oxygen to further break down organic matter in the effluent. This process is more efficient than anaerobic digestion and results in the mineralization of organic compounds.
  • Simplified Reaction: (CH₂O)_n + nO₂ → nCO₂ + nH₂O

3. Chemical Processes:

• Nutrient Removal: Soil adsorption and microbial activity play a role in removing nutrients like nitrogen and phosphorus from the effluent.
  • Nitrification: Ammonia (NH₃) is converted to nitrite (NO₂^-) and then to nitrate (NO₃^-) by aerobic bacteria (e.g., Nitrosomonas and Nitrobacter).
  • Denitrification: Nitrate (NO₃^-) is converted to nitrogen gas (N₂) by anaerobic bacteria. This process requires a carbon source.
  • Phosphorus Adsorption: Soil particles, particularly those containing iron and aluminum oxides, can bind phosphorus, preventing its migration into groundwater. Adsorption capacity is finite and depends on soil composition.

4. Physical Processes:

• Filtration: Soil acts as a physical filter, removing suspended solids and particulate matter from the effluent.
• Adsorption: Soil particles attract and hold onto contaminants (e.g., viruses, bacteria) through electrostatic and Van der Waals forces.
• Dispersion: Spreading the effluent over a large area within the drainfield to maximize contact with the soil and enhance treatment.

Due Diligence During the Inspection Period: Agent’s Responsibilities

The buyer’s agent has a fiduciary duty to advise the buyer on all aspects of the property, including the septic system. The inspection period is crucial for assessing the system’s functionality and identifying potential issues.

1. Septic System Inspection:

• Professional Inspection: Strongly recommend a thorough inspection by a qualified septic system professional. This inspector should be licensed and experienced in Hawaii’s specific soil conditions and septic system regulations. The inspector will:

  • Locate the septic tank and drainfield: Use maps, permits, and physical observation to pinpoint their exact location.
  • Inspect the septic tank: Assess tank condition (cracks, leaks), baffle integrity, sludge and scum levels, and overall structural integrity.
  • Inspect the drainfield: Look for signs of failure, such as standing water, soggy ground, foul odors, or excessive vegetation growth in the drainfield area. Evaluate soil conditions.
  • Perform a hydraulic load test (if applicable): This involves introducing a known volume of water into the system to assess its ability to process wastewater.

• Review Existing Records: Obtain and review any available records pertaining to the septic system:

  • Permits: Original installation permits, repair permits, and alteration permits.
  • Maintenance Records: Pumping records, repair invoices, and inspection reports. Pumping frequency is a key indicator of system health.
  • As-Built Drawings: Detailed diagrams showing the location and configuration of the septic system components.

2. Soil Evaluation:

• Percolation Test (Perc Test): Determines the rate at which water drains through the soil. This is critical for assessing the soil’s ability to treat and disperse effluent. A perc test should be performed by a qualified professional. The percolation rate is typically expressed in minutes per inch (min/in).

  • Formula: Percolation Rate = Time (minutes) / Distance (inches)
  • Acceptable percolation rates vary depending on local regulations and soil type.

• Soil Morphology: Examine soil texture, structure, color, and drainage characteristics. Soil texture (sand, silt, clay) influences permeability and filtration capacity.

3. Water Quality Testing:

• Groundwater Testing: If there are concerns about potential groundwater contamination, advise the buyer to test the well water (if applicable) or nearby water sources for indicators of septic system failure, such as:
  • Coliform Bacteria: Indicate fecal contamination.
  • Nitrates: Elevated nitrate levels can indicate septic system effluent.
  • Chlorides: High chloride concentrations can also be indicative of wastewater contamination.

4. System Usage and Maintenance:

• Assess Water Usage: Determine the number of occupants the system is designed to serve. Overloading the system can lead to premature failure. Water conservation measures can extend the life of the system.
• Educate the Buyer: Provide information on proper septic system maintenance:
  • Regular Pumping: Advise the buyer to schedule regular septic tank pumping (typically every 3-5 years, depending on usage).
  • Water Conservation: Encourage water-saving practices, such as low-flow fixtures and efficient appliances.
  • Avoid Disposing of Inappropriate Materials: Advise against flushing non-biodegradable items (e.g., diapers, sanitary napkins, wipes) or pouring grease, oils, and chemicals down the drain.

5. Negotiation and Contingencies:

• Negotiate Repairs or Replacement: If the inspection reveals issues with the septic system, advise the buyer to negotiate with the seller for repairs or a price reduction to cover the cost of replacement.
• Contingency Clause: Ensure the purchase agreement includes a contingency clause that allows the buyer to terminate the contract if the septic system inspection is unsatisfactory.

Practical Application Example:

Imagine a buyer is purchasing a property in Hawaii with a cesspool that was converted to a septic system in 2015. The agent should advise the buyer to:

1. Locate the septic system permit from 2015.
2. Hire a qualified septic system inspector to verify the system was installed according to the permit and is functioning correctly.
3. Request the seller’s pumping records to verify regular maintenance.
4. If the property has a well, test the well water for coliform bacteria and nitrates.
5. Include a contingency clause in the purchase agreement allowing termination if the septic system inspection reveals significant issues or the well water is contaminated.

Breakthroughs and Impact:

The development of effective septic systems has been crucial for public health and environmental protection in areas without centralized sewer infrastructure. Advances in wastewater treatment technologies, such as engineered wetlands and advanced treatment units, are further improving the performance and sustainability of on-site wastewater treatment systems. The shift from less effective systems like cesspools (now illegal in many parts of Hawaii) to modern septic systems represents a significant advancement in safeguarding water quality and preventing disease. The ongoing research into optimizing biological processes and developing more efficient nutrient removal techniques promises to further enhance the performance and longevity of septic systems in Hawaii and worldwide.