SewperCoat 2000HS Regular, a mortar specifically designed for sewer repair, was installed in a critical connection chamber at HRSD's James River Wastewater Treatment Facility. This area was initially chosen because of its extreme corrosive environment.

Eleven years after rehabilitating with SewperCoat, the structure has exhibited virtually no signs of corrosion or degradation. The original portland cement based concrete structure had corroded in excess of 3” in only 7 years of service.

Since its rehabilitation with SewperCoat, the surface pH measurements taken over the past 11 years have ranged from 2.8 to 4.0.

These observations have confirmed the of SewperCoat. The bacterial

activity, and subsequent acid production, have been minimized, as reflected in the lack of corrosive attack and consistently higher pH measurements.

Based on previous experience with this structure and laboratory research, portland cement based concrete would have exhibited a probable surface pH level of approximately 1.0, and would have again corroded to a degree well past the reinforcing steel durin this time period.

This unique installation has confirmed the predicted performance of SewperCoat in a highly corrosive wastewater environment. This history also validates SewperCoat as an economical, long term repair material.

PROTECTIVE REACTIVE BARRIER EFFECT

®SewperCoat 2000HS Regular

Reference SheetReference US 11/91

Dry-Gunite Application

Description1

% In November 1991, Hampton Roads Sanitation District (HRSD) installed SewperCoat 2000HS Regular in a connection chamber.

% After only 7 years of service, the origonal portland cement based concrete had corroded more than 3”, exposing large areas of reinforcing steel. The surface pH at this time was measured at 1.5.

% Contractor: Pressure Concrete

% Method of Placement: Dry Gunite

During each evaluation a silicon seal used to control odor must be broken.

Allentown Equipment manufactures a common piece gunite installation equipment.

The Reference

LAFARGE CALCIUM ALUMINATES, INC.1316 Priority Lane, Chesapeake, VA 23324Phone: (757) 543-8832 Fax: (757) 543-1002

After one year of operation, the H S gas measured 2

18-20 ppm (the chamber was opened one day before evaluation) and the pH on the surface of the walls was measured at 3.0.

The surface appearance was excellent with absolutely no sign of corrosion or degradation.

One Year Evaluation3

Before...$

...and After."

The walls remain in good, sound condition with no signs of corrosion. The sulfur buildup is evident but has not caused any change in the condition of the SewperCoat surfaces.

The pH measured above the effluent level on SewperCoat surface was approximately 2.8. This is a typical pH evolution on the surface of a SewperCoat lining.

After 1 year of service, the pH level measured on the !SewperCoat surface is approximately 3.0. Other materials could develop pH levels as low as 1.0 (100 times more corrosive).

#Wire mesh is only necessary if the lining thickness will exceed 2 1/2 inches per application pass. Additional material can be applied, without wire mesh, as soon as initial material has begun to set (2 hrs).

A "gunned" finish is a $common finish for gunite applications. Typically, the surface is smooth enough due to the excessive c o m p a c t i o n d u r i n g application.

The walls continue to exhibit a hard, sound surface with no corrosion evident. The sulfur buildup is again evident, even though it was thoroughly washed clean during the last visit.

The pH measured above the effluent level on the SewperCoat surface is still approximately 2.8. The neutralization capacity of SewperCoat is apparent at 2 years with the consistent surface pH measurements.

Two Year Evaluation4

LAFARGE CALCIUM ALUMINATES, INC.1316 Priority Lane, Chesapeake, VA 23324Phone: (757) 543-8832 Fax: (757) 543-1002

The general condition of the SewperCoat is excellent. It is very sound with no signs of damage from corrosion. There is now a superficial buildup (”slime layer”) evident on most of the surface. The formation of this slime layer confirms Thiobacillus activity within this structure.

The SewperCoat surface pH measured above the effluent level is approximately 3.0. The laboratory predicted surface pH for this time period was 2.2. In either case, the pH has evolved to a significantly higher level than would have occurred on a portland cement based surface.

The H S concentration was measured at 30 ppm.2

Three Year Evaluation5

Inspection of the junction box demonstrates a hard, !sound surface without any sign of corrosion.

This inspection proved to be quite analogous to the three year evaluation. A micro cement layer (<1 mm) has worn away, however this was attributed to repeated scrubbing and cleaning of the structure, including the evaluation periods.

The surface pH level was measured at 2.9 while the hydrogen sulfide level continued to exhibit aggressive values (> 20 ppm). The oxygen depletion level was also recorded at 9.6 during this evaluation.

Four and ½ Year Evaluation6

Five Year Evaluation7

In January 1997, the junction box was again evaluated to determine surface corrosion, surface pH and hydrogen sulfide level.

As seen before, the only corrosion is that of the micro cement layer (<1 mm) or better known as the latency. The pH level was measured at 2.9 and hydrogen sulfide level measured higher than the last evaluation at 28 ppm.

SewperCoat continues to demonstrate the unique capability of maintaining a significantly higher pH level than that of other construction materials. In addition to the elevated pH, SewperCoat also continues to exhibit rock hard properties.

! The surface pH shown above continues to demonstrate SewperCoat’s ability to elevate the pH (pH3 vs. PH1).

! The periodically washed surface continues to demonstrate

excellent performance and rock solid properties.

(6 month evaluation periods)

LAFARGE CALCIUM ALUMINATES, INC.1316 Priority Lane, Chesapeake, VA 23324Phone: (757) 543-8832 Fax: (757) 543-1002

The 8 ½ year evaluation yielded results similar to those of recent previous evaluations. The hydrogen sulfide level was again measured at >100 ppm. The only noted corrosion was again confined to the micro cement layer (< 1 mm). The pH was measured surprisingly at 4.0 on the surface of the SewperCoat. A complete failure of the inert material coating the iron access casting was also noted.

Eight and 1/2 Year Evaluation

"The measured surface pH continues to reveal values >3.0.

"The inert coating applied to the iron access casting is now failing.

Six Year Evaluation

The six year evaluation was almost identical to the five year inspection. There was still only a minor surface latence apparent. The surface pH was measured at 3.0 and hydrogen sulfide level was in excess of 100 ppm. The oxygen level recorded at this time was 16.5%.

The 10 ½ year investigation showed some very interesting results. The SewperCoat lining still exhibits a surface pH of 4.0. The previously noted corrosion of the iron casting has continued and gotten progressively worse. The pH measurement taken on the iron surface was at 1.0. This pH measurement was taken no more than 6” away from the SewperCoat pH location. This extreme difference in pH, taken on two adjacent surfaces, verifies that reactivity and neutralization capacity do indeed play a significant role in a materials ultimate performance in this type of service environment.

Ten and 1/2 Year Evaluation10

! After 10 ½ years, the SewperCoat is still in excellent condition, being structurally sound and rock solid.

A pH of 1.0 is measured on $the iron casting, while...

#...Only inches away the SewperCoat surface exhibits a pH measurement of 4.0.

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0 1 2 3 4 5 6 7 8 9 10 11Years

pH

pH measuredon install edSewperCoat

Predicted pHevolution onSewperCoat

Typical pHevolution onportlandconcrete

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LAFARGE CALCIUM ALUMINATES, INC.1316 Priority Lane, Chesapeake, VA 23324Phone: (757) 543-8832 Fax: (757) 543-1002