Aqua Freed® & Aqua Gard® Case Studies

Successful Rehabilitation of Over 6,000 Water Wells Worldwide

The AQUA FREED® well rehabilitation process has been extremely successful in restoring lost capacity to more than 7,000 wells worldwide during the past 24 years. Below is a small sampling of before and after results from the AQUA FREED® well rehabilitation and AQUA GARD® preventative maintenance processes.

Case Study - Ringwood Borough, NJ - Beattie Well #9

Client: Borough of Ringwood
Location: Ringwood, NJ

Well #9 was originally installed in 1991 to a depth of 100 ft., with a with a 12” diameter screened interval from 80-100 ft and production estimated at +/-500 GPM. The well suffered a gradual decline, requiring rehabilitation several times between 1991 and 2011 using high pressure jetting/swabbing and returning the well to +/-315 GPM for a week before returning to its pre-treatment level. This condition caused the Borough significant financial expense with the purchase of supplemental water from a neighboring community.

In Mid-September 2011, STI was contracted to rehabilitate the well using its Aqua Freed, CO2 injection method as a last resort prior to drilling a replacement well. Pre-treatment production data as provided by the client revealed the following:

Pumping Rate: 215 GPM

Pumping Level: 71.9 ft.

Specific Capacity: 3.44

The pump was removed and a video inspection performed, revealing significant buildup of encrustation with large tubercle in the upper casing, as well as the screen clogged with iron incrustation. A packer was installed to confine the injection of 2.5 tons of CO2. The well was then mechanically re-developed using dual swab airlift method for 24 hours and a post treatment video inspection performed which revealed the well casing and screen to be clean.

Pre Treatment

Post Treatment

The customer’s pump was reinstalled and a step rate pumping test performed producing the following results.

When re-installing the customers pump, the well was equipped with an Aqua Gard preventive maintenance system to maintain production rates and pumping efficiencies. Scheduled maintenance was originally anticipated at 12 month intervals; however the client noticed some pumping level decline and requested a service at 6 & 12 months respectively, followed by annual events which have allowed the well to continue at +/-500 GPM.

As indicated in the opening paragraph, the Borough of Ringwood was forced to purchase supplemental water to meet its demands each and every year. The following table reflects the supplemental volumes purchased and cost for purchase. In 2010, the full year preceding an Aqua Freed treatment the Borough purchased 100,000,000 gallons of supplemental water. Because the Aqua Freed treatment was in treated in September and the well returned to service in the 4th quarter of the year, supplemental water was required for the first 3 quarters of the year.

Case Study - North Carolina

A definitive case study confirming the benefits of preventive water well maintenance.

For the past 15 years, Aqua Gard has been successful in keeping wells operating within a +/-10% margin of the peak production and specific capacity following a successful rehabilitation.

When water wells are installed, 1 of 3 go forward scenarios exist:

1. No maintenance or preventive maintenance performed, operating the system to eventual failure.
2. Perform routine maintenance to the well, which is most common.
3. Perform regularly scheduled preventive maintenance to the wells.

Approximately 7 years ago, STI was contacted to clean a 4-well ground water system, which was a component to a fairly large multi-system water utility.

All 4 wells in the system were cleaned and equipped with Aqua Gard preventive maintenance systems to maintain the newly increased production and elevated pumping performance. The results obtained and the data provided are from an independent source related to the Utility.

Conclusion: Particularly for water utilities, an aggressive preventive water well maintenance program will cost less in the years to come, drive down pumping energy costs and produce more water to sell. For municipal and industrial systems the same maintenance and pumping energy cost savings apply along with not having to purchase expensive supplemental supply or notify constituents of “water usage limitations” resulting from lost supply.

Case Study 1

Client: New York State Office of General Services (OGS)
Site: Bedford Hills CF, Bedford Hills, New York

Well ID: Well #9
Well Depth: 70 ft bg
Well Diameter: 12 inch
Well Construction: Gravel packed
Screen Interval: 40 – 69 ft bg.
Aquifer: Sand and gravel
Original Specific Capacity: 4.6 gpm/ft @ 110 gpm

Well #9 was installed in 1964 but was never used due to a low yield (110 gpm). In April of 1997 Well 9 was redeveloped using the AQUA FREED® process followed by surge block agitation. Prior to redevelopment well #9 was televised and pump tested. The video inspection revealed a significant amount of encrustation on the well screen. The interval between 40 ft bg. and 54 ft bg. was extensively clogged with only the vertical supports visible. From 54 ft bg. to 69 ft bg. the screen was less clogged. The results of the pre and post-redevelopment efforts are summarized below:

Well #9 was pumped at a rate of 260 gpm for a 24-hour period. The specific capacity values at the completion of the test were two times greater than the original specific capacity and three times greater than .the pre-redevelopment specific capacity. The long term recommended pumping rate of well 9 is 225 gpm.

Case Study 2

Client: New York State Office of General Services (OGS)
Site: Greenhaven Correctional Facility, Stormville, New York

Well ID: Well #3
Well Depth: 77 ft bg
Well Diameter: 10 inch
Well Construction: Gravel packed
Aquifer: Sand and gravel

In April of 2008 well #3 was redeveloped using the AQUA FREED® process followed by mechanical development (surging and pumping). Pre-development video inspection and step rate pumping test were performed to verify well integrity and to determine the pretreatment yield and efficiency, with the results of the pumping data reflected below. The AQUA FREED® process was performed, followed by 2 days of mechanical development. Post re-development pumping data as seen below, increased the pumping rate from 150 GPM with a specific capacity of 3.23 to a pumping rate of 350 GPM at a specific capacity of 7.37, more than doubling both yield and efficiency. NOTE: Well #3 had been previously rehabilitated in January of 2003, with good results. After the treatment in 2008, the well was equipped with AQUA GARD®, now allowing for scheduled, cost efficient preventative maintenance, thereby maintaining increased production and efficiency at reduced cost.

The post treatment video survey revealed a considerable improvement in the condition of the screen with the results of the pre and post redevelopment data shown below.

Case Study 3

Client: Village of Greenwood Lake
Location: Greenwood Lake, NY

Well ID: Well E
Well Depth: 96 ft.
Well Diameter: 8″
Well Construction: Screened
Aquifer: Sand and gravel

Well E historically suffered from lost capacity and poor water quality problems as a result of severe manganese plugging. Well E had been cleaned in the past using conventional chemical and acid methods in an attempt to recover the lost capacity and improve the water quality, with marginal success. A video inspection revealed significant buildup on the well screen and in 2005, Subsurface Technologies was contracted to use the AQUA FREED® process as the solution to this chronic plugging problem. The well was brushed, followed by an Aqua Freed injection and then mechanically developed for 1 day. A post video inspection revealed a completely clean screen and a post treatment step rate pumping test performed. Results of the pre and post pumping test are shown below. In addition to the increased yield and efficiency, water quality was greatly improved due to complete deposit removal. This well was then equipped with AQUA GARD® to prevent future lost capacity and maintain water quality.

Case Study 4

Client: Town of Colonie
Location: Colonie, NY

Well ID: Latham Water District #4
Well Depth: 40 ft
Well Diameter: 24″
Well Construction: Gravel packed
Screen Length: 25 ft
Static Water Level: 15 ft TOC

On February 15th, 2013 a pre-treatment step rate pumping test was performed to Latham Water District #4 at 400, 600 and 681 GPM respectively using the existing submersible pump. The test was terminated early due to declining water levels. The pumping equipment was removed and a pre –treatment video inspection preformed which revealed significant plugging throughout the entire length of the screen. Following the video inspection the well was rehabilitated during a two day period using the Aqua Freed liquid CO2 injection process, followed by 3 days of mechanical development using a dual swab can pump. After final development, a post treatment video inspection was performed which revealed the entire length of the screen was completely clean. The pump was reinstalled in the well and a post-treatment step rate pumping test performed at 400, 600, 800 & 880 GPM respectively using the same methodology as the preliminary test. The tables below reflect the value the Aqua Freed treatment had on this well, increasing specific capacity by greater than 80% at the same time increasing production by 30%.

Case Study 5

Client: Village of Montgomery
Location: Montgomery, NY

Well ID: Holt Well #3
Well Depth: 50 ft
Well Diameter: 12″
Well Construction: Screened
Screen Length: 10 ft

In 2000 the Village of Montgomery installed well #4 to serve as the primary water supply for the village, because well #3 was unable to produce an adequate sustainable yield. In 2004, well #4 began to decline, however could not be taken out of service until a replacement well was put into production. A video inspection was performed on well #3 revealing little screen plugging, however at the advice of Subsurface Technologies the town commenced with using AQUA FREED® to clean #3 in spite of the results of the video. As you can see in the table of results below, well #3 responded very well to treatment signifying that although the plugging on the screen was minimal, the well experienced considerable formation and gravel pack plugging behind the screened interval. Well #3 was then included in the system and well #4 cleaned with AQUA FREED® with excellent success. Both wells were immediately equipped with AQUA GARD® preventative maintenance devices and scheduled for service on a 6 month cycle to insure that production and efficiency were maintained and have been performing well since that time.

Investor Owned Water Utility – Aqua America, PA – AQUA FREED® & AQUA GARD®

In November of 2004, AQUA GARD® was installed on 1 of a 5 well potable water supply system.The well was completed to 540’ and produced 160 GPM with a pumping level of 259’. Almost immediately well yield and efficiency began a steady decline. Within 6 months the well had lost 35% of its yield and 37% of its efficiency. The well was cleaned and AQUA GARD® installed. Based on the historical performance the well would have required cleaning at 6 month intervals to minimize lost yield and reduced efficiency. The following represents the actual cost benefit analysis for installation of an AQUA GARD® preventative maintenance system at this site.

Industrial Site – AQUA GARD®

A 9 well industrial site in the northeast required rehabilitation every 6 months to restore lost capacity caused by very high levels of biological activity and producing extremely poor water quality, rendering the wells un-potable. In 2001 AQUA GARD® was installed in 5 of the 9 wells, followed by quarterly AQUA GARD® preventative scheduled maintenance. The result: increased yield, sustained higher pumping levels & efficiencies, and significantly reduced cost. Plant demand was then fully met by the 5 wells equipped with AQUA GARD®, reducing maintenance and energy costs during the following 3 year period as shown in the cost benefit analysis below. Water quality was also greatly improved thereby lowering treatment costs.

Poweshiek Water Association – Tama, Iowa- AQUA FREED® & AQUA GARD®

Poweshiek Water Association is a public water utility that provides potable water to 10 counties in Iowa. The Tama well Field has 11 groundwater wells required to meet its 2.2 million gallon per day demand for its customers. Although the utility was performing “shock chlorination” to its wells the production rate was declining. In the spring of 2004 STI was contracted to clean one well using AQUA FREED® for evaluation purposes. It was Poweshiek’s intention to evaluate the performance of the treatment during the next 12 months and determine if continued use was warranted. Within 6 months, the utility was extremely pleased with the performance of the treatment and engaged STI to rehabilitate 2 additional wells and equip the 3 wells treated to date with AQUA GARD® preventative maintenance system. By the spring of 2006 Poweshiek had fully recognized the benefits of using AQUA FREED® well rehabilitation technology and AQUA GARD® preventative maintenance systems, and accelerated its rehab and maintenance program to clean and equip all of its 11 groundwater wells to maintain the needed well yields. Today, service is performed annually to each well for a fraction of the cost of well rehabilitation, while maintaining consistent system production.

Typical “SEMI-ANNUAL self treatment” result:
25-35% decrease in flow rate not associated with equipment failure over the duration of the cleaning cycle and raw water line pigging
90-100% capacity restoration after cleaning and raw water line pigging

Typical “ANNUAL Subsurface Technology treatment” result:
10-15% decrease in flow rate not associated with equipment failure over the duration of the annual cleaning cycle and raw water line pigging
90-110% capacity restoration after initial AquaFreed treatment followed by annual AquaGuard® treatments and raw water line pigging

United Water of New York

A 12″ diameter gravel pack well was constructed in 1975 and when new had a specific capacity of 13.6. Iron bacteria fouling was so severe that the client resorted to hypochloride treatments every 30 days with minimal results. Historically the well had been redeveloped using every traditional technique (chemical,acid, mechanical development, etc.). Immediately prior to using the AQUA FREED® treatment the wells specific capacity had declined to 10.2. After a 2 day treatment the wells specific capacity had increased to 17.19 and maintained safe pumping levels for 3 years at which time the well was redeveloped by AQUA FREED® returning it to excess its original production levels.

Stillwater

The Village of Stillwater NY was performing well rehabilitation to its 5 groundwater wells using its own equipment and staffing for chemical and acid treatments. Results were marginal and short lived, not due to staff or equipment, but rather because this cleaning method was not effective at completely removing deposits from the formation. STI was contracted to treat one well with AQUA FREED® and equip the well with an AQUA GARD® preventative maintenance device. Shortly thereafter due to excellent results from the AQUA FREED® treatment and AQUA GARD® service, the Village engaged STI to clean and equip all of its wells. Today the Village is enjoying all the water to meet their needs at a greatly reduced cost and with no interruption.

Super Fund Site in Northeastern U.S.

This product recovery well was part of a 13 well ground water remediation system at a Super Fund site operated by a large industrial customer. The wells were installed in 1994 losing capacity rather quickly. Traditional acid/chemical treatments were performed on all 13 wells with little to no improvement. Subsurface Technologies, Inc. was contracted to treat one well early in 1996 increasing the specific capacity from .10 to 1.57 thereby allowing the more rapid extraction of the contaminated water. Since the clients original use of AQUA FREED® to rehabilitate this well, all wells are cleaned using Aqua Freed every 3 years to meet capture requirements.

Augusta County Service Authority in Staunten, VA

In 1999 STI was contracted to clean and redevelop a well that had been plagued with Iron Related Bacteria, resulting in poor water quality and loss of capacity. AQUA FREED® completely restored the wells yield and efficiency. In 2006, STI was again engaged to clean the well, however, this time the client requested the well be equipped with AQUA GARD® after the AQUA FREED® treatment was complete, in an effort to maintain the wells yield and efficiency at lower cost.

Collector, Horizontal, Angle & Directional Wells - Case Studies

City of Sioux Falls, South Dakota - Collector Well

Well construction consisted of a 13 ft. inner diameter concrete caisson inserted to a depth of 39 ft. 4 @ 12″ diameter slotted lateral pipes extended from various points at the caisson into the gravel aquifer to distances of approximately 150 ft. When originally constructed in 1983 the wells specific capacity was 69gpm/ft. of draw down. Early in 1992 and due to severe biofouling and mineral encrustation, the wells specific capacity had declined to 46.6gpm/ft of draw down. Several redevelopment efforts resulted in limited success. After a 7 day AQUA FREED® treatment the well’s specific capacity had increased to 72.5gpm/ft. of draw down.

Poweshiek Water Association - Angle Well

In 2008 PWA constructed a new treatment plant and wellfield. PWA specified the AquaGard® equipment to be installed on these new angle wells based on the success we have enjoyed at our other wellfield. The capacity of two of the three new wells were only a fraction of design flow rate. Subsurface technologies mobilized on extremely short notice, even though they were extremely busy, and through the use of Aqua Freed® CO2 injection, significantly improved the development of these wells. The overall result from this effort was a well capacity increase of between 90 and 100%. All other avenues for development had been attempted with small percentage based increases in capacity with each attempt. Had we not been able to use Subsurface Technologies to aid in the development process, PWA would have been faced with enormous costs to drill more wells and install the associated pipeline etc. As far as PWA is concerned This was a project saver both from a money and time perspective as we were starting a completely new and independent treatment plant, distribution system, and wellfield with a new customer base relying on our water.

Des Moines Water Works - Horizontal Well

Site: Maffitt Water Treatment Plant
Des Moines, Iowa
Horizontal Water Supply Well

Well ID: Horizontal Well
Well depth: 30 ft bg.
Well diameter: 12 inch
Well construction: Naturally Developed with Pipe Based Wire Wrap Well Screen
Screen interval: 1220 feet Horizontal Length
Aquifer: Sand and gravel

The first horizontal water supply well in the USA was constructed in 1998 by Des Moines Water Works. This well was installed parallel to the bank of the Racoon River. To begin construction a borehole was drilled at 30° to a depth approximately 30 feet below ground surface. To maintain the integrity of the borehole during the drilling process Baroid drilling mud was used. With blank casing attached to both ends of the screen, the entire string was pulled through the drilled hole. An 18 inch casing extended beyond ground surface on one end of the well and a 12 inch casing extended beyond ground surface on the other end on the well Based upon hydrogeological evaluation the well was expected to produce approximately 2000 gallons per minute. After the well construction was completed the well was developed for weeks using traditional development techniques. The techniques used included, application of Sodium Acid Pyro Phosphate (SAPP), the injection of gas into the well followed by the development, isolating zones (5 feet zones) and pumping with a submersible pump. After weeks of development using traditional techniques the well produced approximately 800 gpm, far below Des Moines Water Works expectation and leaving them to evaluate the next step . After considering their options, Des Moines Water Works decided to use Aqua Freed® (Liquid Carbon Dioxide) technology. Prior to beginning the treatment, a pump test was performed to accurately reflect the pre treatment well yield, still resulting in 800 GPM. It was decided to use another application of SAPP and then isolate 5 foot zones while pumping. The results were still the same. The Well was then sealed at both ends and gaseous and liquid carbon dioxide injected into one end followed by the injection of carbon dioxide injected into the other end to insure complete technology application. A total of 60 tons of gaseous and liquid carbon dioxide was injected into the well. After treatment the well was pumped in 5 foot isolated zones using a submersible pump. A pumping test was performed in the same fashion as the prior 2 tests to determine the well yield after an Aqua Freed® treatment and the well produced approximately 1800GPM.