Posts Tagged ‘air sparge’

Power, provided

Saturday, November 7th, 2009

A new client requested a sparge & vent pilot-study to assess an operational retail petroleum facility.  ReRem proposed a positive-displacement (PD) SVE skid with VFD, vane compressor, interconnects, labor and generator.  The proposal was accepted, without the generator.  This was a cost-saving measure.  We were assured the facility had ample electricity near our test location and on-site electrician.

Test day: we arrived at 0700, i setup the equipment while they collect base-line measurements.  By 0900 we were ready to start.  No electrician and the distance to power was under-estimated.  We waited.  The electrician arrived at 1100 and promptly left for additional materials.  He returned and completed his work by 1300.

We began the test and collected 4-hours of data, shut-down was prompted by darkness and Health & Safety requirements.  As the test is prescribed for 8-hours, the client was face with a decision: accept a truncated test or continue the following day.  The budget precluded a second day and the unit-cost structure did not acknowledge shorter periods… We conducted a second, half-day test to meet the criteria and the client spent the remainder to the day awaiting the electrician to undo our power supply.

ReRem Equipment provides a truck-mounted diesel generator and pretests all equipment prior to mobilization.  This step assures prompt start-up and timely project execution.  The cost for the generator: $250/day.

Typically, these tests are completed in 10 to 12 hours, including 8 hours of data. Labor for that site was two-days for the PM, geologist, tech, ReRem’s equipment specialist, and the electrician. I don’t think the ‘unit cost’ will cover his proposed savings.

MORAL:  Don’t step over dollars to save dimes.

Helium tracer

Friday, July 31st, 2009

After years of tracer studies utilizing helium to assess transit rates and diffusion coefficients, we are finally honing into a solid methodology.  Typically, HE was injected in conjunction with air-sparge (AS) testing while monitoring the relative HE concentration within an SVE air-stream.  Injected rates, recovery rates and time-lag were recorded.  Results were varied at best.  But was it the injection rate or the detector?

A recent test introduced the HE into an adjacent well, at low pressure and concentrations, for a finite period. The SVE gases were screened and produced a curve, representing the HE concentraton front and threrby the transit time.  Once the levels fell to ‘background’  another well was plumbed and the test repeated.

Distance vs. concentration and distance vs. time-lag were plotted and proved linear in evaluation.  Does anyone have any experience with HE (or other tracer gasses) and detectors used in conjunction with air-sparge?

A sparge and vent pilot-study.

Thursday, December 11th, 2008

A common scope of work for ReRem Equipment Corp is the sparge & vent pilot-study.  Baseline data typically includes headspace VOC’s, depth to water (DTW), dissolved oxygen (DO) and areal distances.  A stepped vacuum is applied to the formation with resultant flow, VOC concentrations and induced vacuum at surrounding wells recorded.  Stepped air-sparge is then introduced.  Data-set collection is client-specified, and commonly includes DTW, DO, and / or inert tracer gases.

We usually provide SVE skid with VFD controller, sparge compressor, generator, interconnect hoses & wellhead adapters, and equipment operator (on-site assistant).  The client (consultant) provides HASP, site-specific instruments, waste containment or carbon beds, SOP with data sheets and qualified personnel.

Typical costs for a 10-hour test, including equipment & operator is $1400.  This excludes mobilization and perdiem from Albany, NY.