Passive Borehole System for Soil Gas Remediation
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Solution Overview
Problem
Existing soil and groundwater remediation systems are costly, inefficient, and require extensive infrastructure, taking years to decades to complete, and are limited in their ability to effectively treat volatile and semi-volatile contaminants due to their reliance on expensive mechanical components and inability to facilitate area-wide mixing of atmospheric gases and temperatures.
Innovation Solution
A passive system comprising a large borehole with a gas-permeable liner and porous fill material, along with smaller boreholes, utilizes variations in atmospheric barometric pressure to intercept and vent vapors from contaminated soil and groundwater, creating a preferential pathway for vapor migration and remediation through the use of porous materials and vegetation for enhanced contaminant degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expensive engineered treatment wells and above ground infrastructure are used, then remediation can be performed, but construction and operating costs increase significantly
Solution Approach 1:
The invention extracts the essential function of vapor interception from complex engineered wells and isolates it to simple boreholes filled with porous material. By removing unnecessary infrastructure components (cased wells, above-ground equipment, mechanical systems), the system achieves remediation effectiveness at minimal construction cost.
Solution Approach 2:
The system uses inexpensive, simple boreholes with porous fill material that can be easily installed and abandoned after use. These temporary, low-cost structures replace expensive permanent infrastructure, allowing cost-effective remediation without long-term maintenance commitments.
2Reliability
If traditional remediation systems with mechanical components are used, then treatment can occur, but the system requires extensive maintenance and has limited adaptability
Solution Approach 1:
The system uses passive barometric pressure-driven airflow that requires no mechanical components, power sources, or active control. The porous fill material self-regulates vapor transmission based on natural pressure differentials, eliminating maintenance needs and allowing installation in diverse locations including areas with pedestrian or vehicular traffic.
Solution Approach 2:
The system exploits natural variations in atmospheric barometric pressure as the driving force for vapor movement. By changing from active mechanical control to passive exploitation of natural pressure parameters, the system gains adaptability to various installation environments while maintaining treatment capability.
3Reliability
If remediation systems operate for years to decades, then complete treatment can be achieved, but the time required for remediation becomes excessively long
Solution Approach 1:
The system operates continuously to extract vapors from the subsurface, maintaining constant remediation action. The passive barometric pressure-driven system requires no shutdowns for maintenance or operation changes, enabling uninterrupted vapor removal that accelerates treatment completion while ensuring thorough contaminant removal.
4Reliability
If cased wells with screens are used, then groundwater can be treated, but the system cannot facilitate area-wide mixing of atmospheric gases and temperatures
Solution Approach 1:
The system uses porous fill material in simple boreholes that allows free movement of gases and vapors throughout the subsurface area. This porous structure facilitates area-wide mixing of atmospheric gases and temperatures without requiring complex cased well infrastructure, screens, or confined treatment zones.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system significantly reduces construction and operating costs, increases remediation efficiency, allows for widespread contaminant treatment, and can be installed in various locations, including areas with pedestrian or vehicular traffic, while eliminating the need for post-use removal and maintenance, thereby offering a more effective and cost-efficient solution for soil and groundwater cleanup.
Implementation Method 1
volatile and semi-volatile materials can also evaporate back into the vadose zone and become part of the soil gas if favorable conditions exist
Implementation Method 2
have a Henry's Law Constant greater than 1*10−5 atm-m3/mole
Implementation Method 3
The moving forces for diffusion are the concentration gradients of the various compounds and elements, resulting in migration from zones of higher concentrations to zones with lower concentrations
Implementation Method 4
Convective transport on the other hand occurs when the soil gases move through the soil pores under the influence of an external driving force. The convective forces may include variations in barometric pressures, wind gusts occurring above the soil surface, as well as density driven transport caused by changes in subsurface temperatures and moisture content.
Implementation Method 5
Air Pressure fluctuations in a prairie soil, Soil Science Society of America Journal, v. 62, pp. 553-563
Data Source
AI summary
A system for intercepting, treating and venting vapors from contaminated soil in the vadose zone and from contaminated groundwater includes a large borehole and at least one small borehole each having an open top end, a porous liner against the outer wall and porous fill material inside the liner. The fill material can include materials to retard and degrade contaminants in the vapors. The large and small boreholes can have impermeable sections in the liner, and impermeable ground cover around the top ends. The large borehole can also include a slotted aeration tube in the borehole and vegetation planted in the open end of the borehole. A method for intercepting, treating and venting of vapors from contaminated soil in the vadose zone and contaminated groundwater includes the system and pulling vapors out the top end of the large borehole with variations in atmospheric barometric pressure.