Alchatek Blog

Why Repair Groundwater Infiltration in Concrete Infrastructure?

As outlined in our previous blog posts, Mitigating I & I - An Ounce of Prevention is Worth a Pound of Cure and Spend a Little on Infrastructure Infiltration Repair, Save a LOT on Wastewater Treatment Costs, there are many dangers associated with sanitary sewer overflows, lots of funds available for infiltration repair, and many dollars to be saved by choosing to repair high-volume leaks.

How to Repair Groundwater Infiltration

All of this begs the question: How are these leaks repaired exactly? The first step is to identify high-volume leaks in manholes, lift stations, pipes, and other sanitary system components. Monitor and compare peak vs normal flow rates. Inspect the infrastructure in question and look for gushing leaks. These leaks can be repaired with a small crew of about three people. A repair crew this size typically averages about two manholes per day (depending on manhole size and proximity).

On average, curtain wall grouting an 4-foot diameter x 8-foot tall manhole requires 5 gallons of Spetec PUR HighFoamer. On average, treating joints and pipe penetrations on an 4-foot diameter x 8-foot tall manhole requires 2.5 gallons of Spetec PUR GT380.

For more information on infrastructure infiltration repair, call the Alchemy-Spetec tech support team at 404-618-0438.

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The Cost of Wastewater Treatment

According to an article published by Water Technology Magazine (WaterTechOnline.com), the average cost to treat 1000 gallons of wastewater is $2.06. Let’s take a look at how that $2.06 adds up over time. A 10 gallon per minute leak in a manhole for example equals 5,256,000 gallons of water leaked per year. That adds up to a $10,827.36 per year ($902.28 per month) wastewater treatment cost resulting from that leak alone.

Repair Infrastructure Infiltration & Save Money

Let’s compare that to the average one-time cost to stop all the leaks in a 4-foot diameter x 8-foot tall manhole: $3000 or so depending on local labor rates. This relatively low repair cost is recouped in less than 4 months, considering the monthly wastewater treatment cost of $902.28. This equals $7,000 - $8,000 cost avoidance in the first year alone. In subsequent years, you’re saving the full $10,827.36.

Now multiply those number by all the manholes in your district with large leaks. The numbers are truly staggering.

More Info on Infrastructure Infiltration Repair

For more information on infrastructure infiltration repair, see our blog post Mitigating I & I – An Ounce of Prevention is Worth a Pound of Cure. If you’d like to discuss I & I issues with our experienced tech support team, call 404-618-0438.

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Inflow and infiltration (I & I) are widespread problems for municipalities across North America. The term inflow refers to stormwater entering sewer systems. The term infiltration refers to groundwater leaking into manholes, lift stations, pipes, and other sanitary system components. While there are some methodologies on the market for mitigating inflow, this article is primarily concerned with mitigating infiltration with polyurethane grout.

Dangers Posed by Sanitary Sewer Overflows (SSOs)

According to EPA.gov, sanitary sewer overflows are widespread and pose many dangers to public health:

• The EPA estimates there are at least 23,000 - 75,000 SSOs per year (not including sewage backups into buildings) in the U.S. SSOs that reach waters of the U.S. are point source discharges. Like other point source discharges from municipal sanitary sewer systems, SSOs are prohibited unless authorized by a NPDES permit. Moreover, SSOs, including those that do not reach waters of the U.S., may be indicative of improper operation and maintenance of the sewer systems, and may violate NPDES permit conditions. (Source.)
• Because SSOs contain raw sewage they carry bacteria, viruses, protozoa (parasitic organisms), helminths (intestinal worms), and inhaled molds and fungi. As a result, they may cause diseases ranging in severity from mild gastroenteritis (causing stomach cramps and diarrhea) to life-threatening ailments such as cholera, dysentery, infections hepatitis, and severe gastroenteritis. People may be exposed through:
  • Sewage in drinking water sources.
  • Direct contact in areas of high public access such as basements, lawns or streets, or waters used for recreation. At least one study has estimated a direct relationship between gastrointestinal illness contracted while swimming and bacteria levels in the water.
  • Shellfish harvested from areas contaminated by raw sewage. One study indicates that an average of nearly 700 cases of illness per year were reported in the 1980s from eating shellfish contaminated by sewage and other sources. The number of unreported cases is estimated to be 20 times that.
  • Some cases of disease contracted through inhalation and skin absorption have also been documented. (Source.)

Massive Amount of Funds in Place for Sewer & Stormwater Infrastructure Repair

Fortunately, hundreds of billions of dollars are available for addressing these issues according to EPA.gov:

• The CWSRF (Clean Water State Revolving Fund) was created by the 1987 amendments to the Clean Water Act (CWA) as a financial assistance program for a wide range of water infrastructure projects, under 33 U.S. Code §1383. The program is a powerful partnership between EPA and the states that replaced EPA's Construction Grants program. States have the flexibility to fund a range of projects that address their highest priority water quality needs. The program was amended in 2014 by the Water Resources Reform and Development Act. Using a combination of federal and state funds, state CWSRF programs provide loans to eligible recipients to:

  • construct municipal wastewater facilities,

  • control nonpoint sources of pollution,

  • build decentralized wastewater treatment systems,

  • create green infrastructure projects,

  • protect estuaries, and

  • fund other water quality projects.

• Building on a federal investment of $46.8 billion, the state CWSRFs have provided $145 billion to communities through 2020. States have provided over 42,800 low-interest loans to protect public health, protect valuable aquatic resources, and meet environmental standards benefiting hundreds of millions of people. (Source.)

A Simple Plan for Mitigating Sanitary/Stormwater System Infiltration

The grouting plan outlined below provides the highest return on investment:

1. Inspect manhole and lift stations.
2. Identify large, obvious leaks.
3. Repair with polyurethane leak seal grout. A two-person crew can easily mitigate 10-30 gallons per hour in less than a day. This one day’s work typically equates to $30,000 a year in savings depending on local treatment costs.

For more information on mitigating infiltration with polyurethane grouts, call the Alchemy-Spetec technical support team at 404-618-0438 today.

Want more info on Alchemy-Spetec leak seal products?

What Makes Spetec PUR GT380 Unique?

Spetec PUR GT380 is a hydrophilic, one-component flexible polyurethane injection resin for sealing leaks in concrete.

Unique qualities include:

• Depending on amount of water added, it will form either a  foam or a gel.
• Designed as a multi-purpose foam or gel for varying conditions found in manholes and lift stations.
• Lowest viscosity hydrophilic grout offered by Alchemy-Spetec.

This article features three previously published blog posts on the product.

Spetec PUR GT380 Polyurethane Leak Seal Blog Articles

Shut Off Leaks in Structures Where Movement May Occur provides a basic overview of Spetec PUR GT380. Learn about advantages and applications, as well as additional information. Read more...

Sealing Precast Manhole Joint Infiltration with Spetec PUR GT380 provides an overview and basic installations instructions for sealing standard leaks in precast manhole joints. Read more...

Sealing Gushing Leaks in Precast Manholes with GT380 and Oakum Soakum provides an overview and basic installation instructions for sealing gushing leaks in precast manholes. In this case the product is used in combination with AP Oakum, an oil-free dry jute rope. Read more... 

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What Makes Spetec PUR GT350 Unique?

Spetec PUR GT350 is a hydrophilic, one-component flexible polyurethane injection resin for sealing leaks in concrete.

Unique qualities include:

• Extremely high wet/dry cycling resistance.
• Hydrophilic grout that is still appropriate for above-grade crack injection.
• Immediate in increase in viscosity upon contact with water, which is ideal for shutting down high-flow leaks.

This article features three previously published blog posts on the product.

Spetec PUR GT350 Polyurethane Leak Seal Blog Articles

Sealing Leaks with GT350 provides a basic overview of the product. Learn about advantages and applications, as well as additional information. Read more...

Sealing Manholes with Spetec PUR GT350 provides a breif overview of a manhole leak seal job that one or our customers performed with the product. Read more...

Northgate Link Extension with GT350 provides an overview of a tunnel wall leak seal job one of our customers worked on for Seattle's rapid transit system. Read more...

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AP Pump Saver 195 is a specially formulated oil-based lubricant and protectant. It was designed for use in single-component polyurethane pumps. 

Applications

• Lubricating and protecting oil cup section of Poly Shark pumps.
• Lubricating and protecting packings and seals on other single component pumps.

Advantages

• Greatly extends the life of the pump packings.
• Rejuvenates old, worn seals. 
• Decreases the amount of resin leaking into the oil cup.

After single component pumps have been thoroughly flushed with AP Flush 121, circulate AP Pump Saver through the system for at least 20 minutes.  AP Pump Saver 195 is supplied in 5 Gallon Pails (18.9 Liter Pails) with a removable lid.

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Editor's Note: This article is an updated edition of Charlie Lerman's 2017 article, Crack Injection and Curtain Wall Grouting - Part 4.

Manhole Leak Repair

Leaking manholes can cause unnecessary damage to the environment and can be costly if left untreated. Water leaks create voids that can lead to sinkholes, roadway collapses and system failures. Chemical Grouting is a low cost, durable repair method for manholes that can prolong the life of the structure.

Injection Methods for Manhole Repair

Brick Manholes

• Drill to the outside of the manhole and into the soil through the brick.
• Repair all pipe penetrations, and have AP Oakum ready to help plug leaks.
• Start injection of material at the bottom and work your way up.

Precast Manholes

• Repair all pipe penetrations and apply oakum rings if too wide.
• Drill injection holes into the manhole rings at the four main clock positions (12-3-6-9).
• Start injecting material from the bottom up.

Storm Culvert Leak Repair

Storm culverts transport large volumes of water. Leaks bring exterior soil into the storm culvert, often causing sinkholes above. Chemical grouting these structures is a non–excavation repair, which will seal joints and leaks and stabilize soils. Unlike cement grouts, chemical grouts add little to no weight to surrounding soils. Injection of storm culverts can be achieved by manned entry or via probe grouting from above when access is not considered feasible.

Injection Methods for Culvert Repair

Manned Entry Method

• All joints need to be identified and inspected for any possible concrete repair that may need to be performed prior to the injection process.
• Wide joints should be packed using oakum rope and chemical grout to minimize waste and contain injection grout in the joint. Once prepared, injection can be performed.

Probe Grouting Method

• Map off leaks using a CCTV camera.
• Measure out and mark locations on the street or soil above.
• Drill holes though street or soil above at each location.
• Insert injection pipe to a depth of one foot below bottom of repair point.
• Start injecting a rate of 1 gallon per foot stopping at the top of the pipe.

It is important to remember that a leak is a round-the-clock problem. A small leak can eventually lead to a larger leak, which can eventually become catastrophic if left untreated. The longer the wait before repairs, the more expensive the repair becomes. Call the Alchemy-Spetec tech support team now at 404-618-0438 for assistance on manhole and storm culvert repair projects.

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Some municipalities use a method called vacuum testing to identify potential leaks in their newly constructed manholes and pipes. Leaks can be caused by honeycombed concrete, deflected joints, and poor installation of boots. Sometimes precast units can be cracked by heavy equipment during the installation and backfilling process. Municipalities can implement vacuum testing to ensure that the taxpayer is not footing the bill for a system that will fail and require costly repairs down the line.

Technicians identify leaks in new structures by coating the inside with soapy water. Next, they perform a vacuum test with special equipment that extracts all the air and causes bubbles to appear in the leaking areas. After leaks are identified via vacuum testing, professional leak seal contractors can seal them with polyurethane grout using the process outlined below:

1. Drill a small injection hole near the leak location.
2. Flush the hole with water to clear out any debris.
3. Insert a port into the drill hole.
4. Install a Zerk fitting in the port and connect your injection gun.
5. Inject water into the cracks/voids to make sure the moisture activated grout will react.
6. Inject a moisture activated polyurethane grout such as Spetec PUR F400 or Spetec PUR GT500.
7. After the grout cures, the technicians apply the vacuum test again to determine if the leaks have been repaired.

Leak seal contractors should encourage local municipalities and specifiers to require vacuum testing on structures after they are backfilled. If you’d like assistance in making a presentation on this subject, call us today at 404-618-0438.

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Editor's Note: This article is an updated edition of Charlie Lerman's 2017 article, Crack Injection and Curtain Wall Grouting - Part 3.

What is Curtain Wall Grouting and Why is it Effective?

Curtain wall injection is the process of drilling holes through a structure in a diamond pattern, then injecting the grout into soil on the other side. This procedure creates a curtain wall made of a resin/soil mixture that prevents water from getting back into the structure. It is often required if there are multiple cracks or leaks in a wall. Filling each individual crack may cause you to waste time following the water from crack to crack. Curtain wall grouting allows you to stop multiple leaks at one time and protects the structure on a long term basis.

This procedure was first performed in 1960 on a sewer manhole with a multiple leak problem. As described above, chemical grout was injected through to the outside of the manhole. This created a “positive side seal” (on the side the water was coming from), blocking water from penetrating the joints of the structure.

This method is still used today.  It is effective on structures constructed from a wide variety of materials, including wood, steel, concrete, rubble walls, stone, block and brick.

A Brief Overview of the Curtain Wall Grouting Process

Step 1. Injection holes are drilled in a diamond grid pattern.

Step 2. Grout injection begins at the bottom of the wall.

Step 3. Grout is then injected a little higher, so that any excess grouts flows down over the previous injection area. This creates a lapping effect, like shingles on a roof.

Step 4. Injection continues to the top of the wall.

Other Situations Requiring Curtain Wall Grouting

In addition to the “too many leaks” scenario, curtain wall grouting may be required when all cracks cannot be identified in a leaking wall, when previous crack injection has failed, or when a structure has a negative crack injection history. It is also used in masonry, dealing with stone and CMU walls that do not crack inject well.

Material selection is based on various factors such as soils, voids, and moisture conditions. Call us at 404-618-0438 to discuss which material is right for your curtain grouting project.

Alchemy-Spetec Curtain Wall Grouting Products

Spetec PUR H100

Spetec PUR H200

Spetec PUR HighFoamer

Spetec AG200

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Editor's Note: This article is an updated edition of Charlie Lerman's 2017 article, Crack Injection and Curtain Wall Grouting - Part 2.

Crack Injection with Polyurethane

Crack injection has many advantages over other methods.  For example, if you’re sealing a leak in a water tank, you can inject from the outside of the tank. So the tank can remain in service while you repair it. Having to dry a crack, like you do with epoxy resin, is not needed as this material reacts with water. The material also remains flexible at all times.

Crack injections can be applied in both vertical cracks and in horizontal cracks. With vertical cracks, it is imperative to start at the bottom of the crack and work your way up the crack until it is filled. This forces the material up and through the crack and will simultaneously push the water up and out as well. With horizontal cracks, injection can be started at either the left or right end.

The crack injection process is rather simple, but some mis-steps can prove quite costly. For best results, follow the steps below after discussing them in detail with a trained professional...

Crack Injection in 10 Steps

Step 1. Identify crack locations.

Step 2. Estimate the amount of resin you’ll need. (One gallon per 25 linear feet of cracks.)

Step 3. Prepare surface of crack.

Step 4. Drill injection holes at a 45 degree angle.

Step 5. Flush out injection holes with water to remove any debris.

Step 6. Insert injection ports on both sides of crack.

Step 7. Inject water into each port.

Step 8. Start injection of material.

Step 9. Always grout twice.

Step 10. Add water again to activate any remaining resin.

Alchemy-Spetec Crack Injection Products

Spetec PUR F400

Spetec PUR GT500

Spetec AG200

Spetec PUR GT350

Spetec PUR GT380

If you need help choosing a product for your job, call us now at 404-618-0438 to talk to a tech support rep.

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