Infiltration is Draining Your Budget

In Sealing Water Infiltration in Leaking Joints, Inverts and Manholes, we identified strain and efficiency issues treatment plants undergo when groundwater infiltrates city collection systems. These common issues lead to large expenses that accumulate over time if left unchecked. A plan to minimize the damages must address the specific scale of the problems, the age and condition of your overall infrastructure, and your budget. A trusted, experienced team of consultants will prove invaluable as you navigate these uncharted waters.

Effective Manhole Infiltration Repair

According to the EPA, there are over 20 million manholes in the US. Water is infiltrating this aging infrastructure on a daily basis. If you're a municipal administrator or manager, you may already have sent in crews to eliminate the leaking with common waterproofing techniques such as applying hydraulic cement or epoxy coating. But these methods are not always 100% effective in the long term.

One of the most comprehensive ways to completely eliminate all groundwater infiltration in manholes is to encapsulate the structure using curtain grouting techniques. Specialty subcontractors utilize this technique by drilling through to the outside of the wall and injecting highly expansive polyurethane foam into the voids and soils behind it. The expansive chemical grout permeates the soils thanks to its low viscosity and creates a permanent water barrier that can fully encapsulate the manhole if necessary.

When to use Curtain Grouting

We've discussed sealing joint and penetration leaks in previous blog posts, but what if you have numerous leaks, are concerned about voids in the soil, or are repairing a brick manhole? Curtain grouting is especially useful for brick or block manholes that are made up of hundreds of joints and seams where water has many opportunities to penetrate the structure. Encapsulating the structure will polyurethane not only stops infiltration but also fills soil voids. Curtain grouting is just one technique among a handful of methods specially designed for eliminating groundwater infiltration. We recommend getting in touch with our Leak Seal Director of Technical Services, Charlie Lerman, for a free consultation to determine what leak seal methods are best for your infrastructure. Call him today at 404-618-0438. 

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In the United States, tilt-up construction is very common and the resulting joints are typically caulked. The vast majority of the time that is totally sufficient. But what about the joint you find yourself recaulking every six months to a year? While not the norm, they can be a real hassle and a thorn in your side. Enter Spetec PUR F400 and welcome to this blog post!

Spetec PUR F400 is a flexible hydrophobic polyurethane grout. Oakum is a fibrous jute rope that we soak the F400 in and then use to pack the wetted joint from the bottom up. This is a messy but simple process that leaves you with a full-depth seal/bond as opposed to the typical ¼” bond that is standard when caulking. The excess foam can be cut back and caulked to match the existing joints. Caulking is also required on the exterior as F400 is not UV stable, so the caulk protects the F400 from UV and makes the joint cosmetically match the other joints.

The same grout/oakum procedure described above can also be done for joints that are in constant submersion. Standard urethane caulk is not designed for constant submergence and while polysulfides are, they still can have problems with it. F400 is unaffected by wet, dry, wet/dry, or constant submerged environments.

These repair procedures can be applied to pipe penetrations as well. The "oakum soakum" method, as it's commonly known, is a tried and true methodology. But it is also one of the simplest methods for polyurethane chemical grout installation. I equate it to fingerpainting with chemical grouts.

Every grouting job has its unique challenges. Alchemy-Spetec's industry-leading tech support team is here to help! Call 404-618-0438 for assistance with your leak seal job today!

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Treatment plants undergo massive strain and efficiency issues when groundwater infiltrates city collection systems. These common problems lead to large expenses that can accumulate if left unchecked. Identifying the root causes and creating a plan to minimize the damages will be dependent on the scale of the problems, the age and condition of your overall infrastructure, and your budget. Having a trusted, experienced team of consultants will prove to be invaluable as you navigate these uncharted waters.

What is Groundwater Infiltration?

Groundwater Infiltration is an industry term referring to groundwater improperly entering a sanitary sewer wastewater system. This water, which normally drains deep into the ground or is routed to storm drains, ends up being treated. This costly treatment will eat away at your already limited budget while also taking up precious capacity within your collection system. Some common ways groundwater can enter sewer pipes (interceptors, collectors, manholes, or side sewers) are through cracks, leaky pipe joints, connection failures, and poorly maintained manholes.

You may have groundwater infiltration issues if you notice any of the following signs:

1. Your pipes are backed up during rainy seasons. This is often a good indicator of an unforeseen infiltration issue. During the next heavy rain, determine if your manholes are spilling wastewater onto local roadways or fields. This may be a good indicator that you have a surplus of groundwater infiltrating your wastewater systems.
2. Your lift station pumps running continuously or cycling frequently. There may be an issue at hand if your lift station pumps run continuously for a long time after a typical rain event, or if your pumps start and stop frequently. Either event is likely happening because groundwater has entered your sanitary sewer system and is overloading your treatment centers.
3. You can measure significant spikes in flow rates. As you measure and evaluate the effectiveness of your wastewater treatment plant during rainy or high groundwater conditions, readings that return abnormal spikes in inflow likely indicate an I&I issue. While small amounts of infiltration are to be expected, large spikes rarely happen unless there is a significant infiltration issue at hand.

6 Methods to Quantify Infiltration Issues

The warning signs noted above are helpful but indicate basic symptoms only. Once you’ve suspected that groundwater is infiltrating your system, there are 6 proven methods for capturing important data to determine the next course of action. These methods must be performed by a reputable engineering firm or a survey team.

1. Sanitary sewer flow monitoring
2. Manhole inspections and 3D technology
3. Smoke testing
4. Dye testing
5. Pipe inspection/closed circuit television inspection (CCTV)
6. Private property inspections

Cost-Effective and Proven Solutions to Stop Infiltration Immediately

These groundwater infiltration points can be permanently sealed off with crack/joint injection & curtain wall procedures using water-activated polyurethane foam. Pressure injection of these liquid polyurethane resins forces the material into leaking cracks, joints, or voids behind leaking structures. After the polyurethane injection is complete, the polyurethane resin rapidly reacts with water to form a watertight seal.

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

• Failing Sewer Pipe Joints: Groundwater rising and falling puts hydrostatic pressure on pipe and manhole joints, causing them to fail. Point grouting consists of driving injection pipes to the points of failure and injecting a resin such as Spetec PUR HighFoamer. The resin expands and cures quickly to seal off the leaks and fill voids in the soil. Filling the voids with a grout like Spetec PUR HighFoamer also reduces the hydrostatic pressure on the joints. The grout also permeates the soil and increases the load-bearing capacity which can prevent future misalignment of the pipes.
• Pipe and Manholes Inverts: For many years, inverts have been repaired with hydraulic cement. But hydraulic cement fails if there is structural movement over the long-term, and thus leaking cracks/joint return. While hydraulic cement is cheap, repeating the repair process over and over is very expensive and means more confined space entries. Injecting the joints and inverts with a flexible polyurethane grout will provide a long-term repair, often longer than the expected service life of the manhole. Spetec PUR GT380 is the gold standard for these types of repairs, but at times a hydrophobic grout might be needed and thus Spetec PUR F400 would be the grout of choice. With the F400 different reaction times are possible by adjusting the percentage of GEN ACC Accelerator.
• Precast Manhole Joints: A factory-trained specialty contractor can seal precast manhole joints using Spetec PUR GT380. It is a hydrophilic polyurethane material that cures to form a gel or a foam. Because it's a single-component material, you can install it easily without the need for mixing. It can easily penetrate joints before it eventually cures into place, thanks to its low viscosity. Spetec PUR GT380 is a durable, long-term sealing solution that holds up against the harsh sewer environment.

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I&I is a major issue that plagues all collection systems. What can be done about it? There are a number of large-scale and costly ways to address it but often these are overwhelming projects to start. So, let’s take a step back and start small with the manholes. A quick review of rain event data will help pinpoint problem areas. There may be numerous issues in a line, but remember we are going for easy manhole infiltration. Start popping manhole covers. We don’t need to look for every minor leak and the large leaks are easy to identify. Obliviously, flowing water is easy to spot but even if a large leak is not active there are normally clear signs of its existence. These signs include staining, native soils being washed in, or joints with bulging ramnecks. 

So now, with X number of leaking manholes identified, it is time to set a plan. Inverts and precast joints are often the biggest culprits. Often, they have been previously repaired with hydraulic cement. But hydraulic cement can’t deal with movement, and thus leaking cracks return. While hydraulic cement is cheap, repeating the repair process over and over is very expensive and means more confined space entries. Injecting the joints and inverts with a flexible polyurethane grout will provide a long-term repair, often longer than the expected service life of the manhole. Spetec PUR GT380 is the gold standard for these types of repairs, but at times a hydrophobic grout might be needed and thus Spetec PUR F400 would be the grout of choice. 

But what about older brick manholes? Often they are ripped out and replaced. Replacement is not always necessary, can be disruptive, and is very costly. Spetec PUR Highfoamer is an excellent choice for curtain grouting (the ideal application for sealing gushing leaks in old brick manholes). Its set time can easily be field adjusted and its 50x expansion makes it very cost-effective. 

So to review...

1. Perform a quick review of rain event data to identify potential leaks
2. Pop manholes to identify large leaks
3. Grout the defects for a long-term fix

The bonus round is to watch treatment costs drop due to less infiltration! 

Pro Tip: It is best to waterproof when the leaks are active.

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Compatible with a Standard Caulk Gun

INJECTR Series cartridges feature Spetec PUR F400 or Spetec PUR HighFoamer and GEN ACC Accelerator in two sides of the same cartridge. The grout mixes with the accelerator when injected. No need for a full crew or a grout pump. Quicker in and out - less labor.

Available in a Convenient 4 Pack Kit

Both the Spetec PUR F400 and the Spetec PUR HighFoamer kits Include:

4 - Cartridges
4 - Static Mixers
8 - 1/2” Drill Ports
4 - Large Push Connects
4 - Small Push Connects
1 - 10 ft Roll Flexible Tubing

12 Pack Cartridge Case Also Available

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Concrete is the most common building material in the world. While it has high compressive strength, it does not have much tensile strength. It is only since about 1910 that rebar has been specified. Reinforced concrete can and does still crack. So does that matter? Yes, most of the time it does matter.

Epoxies Are for Structural Repair

Epoxies are commonly and very effectively employed to “weld” these cracks back together. End of story, right? Of course not. For structural repairs epoxies are correct and necessary, but what about non-structural dynamic cracking? Well first off, why do we even care if there is a non-structural crack? Sometimes we don’t, but when this non-structural crack is the source of water intrusion action is required!

Water intrusion, besides being unsightly can cause many problems. Slip hazards are an obvious one, remember that rebar we started adding back in the 1910s? It can corrode, per NACE it can expand about 7-8 times its size, causing spalling and even complete failure of the concrete. Epoxy repair of a dynamic non-structural crack does not end well. The crack is there to relieve stress and if it is welded together with epoxy then it cannot move to relieve the stress, which causes what we call mirror cracking (this is a new crack in proximity to the previous epoxy repaired crack). Now we are back to where we started and we wasted time, labor, and materials on a failed repair.

Polyurethanes Are Ideal for Sealing Leaks

Flexible polyurethane grouts are ideal for dynamic cracks. They will waterproof the crack but still allow the cyclic movement - thus no mirror cracking, no leaks, and no corroding rebar. There are two main categories of polyurethane grouts, hydrophilic and hydrophobic. Hydrophilic grouts have more flexibility (higher tensile strength) and better adhesion than hydrophobic grouts. So, the answer seems clear, choose a hydrophilic grout. Hydrophilic grouts are the first choice for most below-grade applications, but since they form an open crosslinking when they polymerize, they can dry out in arid environments. Hydrophobic grouts have a closed crosslink and therefore are unaffected by wet-dry cycling, but have less elongation and lower adhesion strength. So, if you're new to this, it's best to consult an expert when selecting a polyurethane for your leak seal job.

Technical Support for Leak Seal Contractors

When it comes to waterproofing with chemical grouts, product selection and application techniques will make or break a job. Good technical support ensures more production and less product waste. I have over two decades of field experience. I'm happy to share that knowledge in support of all your waterproofing needs, and I am just part of the most experienced grouting tech service team out there. We pride ourselves on education and training in the field, in the classroom, and online. Please let us know how Alchemy-Spetec can be of assistance to you. Call our tech support team today at 404-618-0438.

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In this post, I’m going to personally review two popular methods used to handle water leaks and infiltration. Both hydraulic cement and chemical polyurethane grouts are used in civil applications such as sewer pipe rehabilitation, tunnel or shaft construction, sealing leaking cracks in concrete structures, permeating soil to control the flow of groundwater, filling voids to stabilize soil, and handling common inflow and infiltration issues found all over the world.

This post will reveal the good, the bad, (and the ugly) when it comes to product selection and application. When considering chemical grout or hydraulic cement for your waterproofing needs, we will need to look at:

• Features
• Costs
• Applications

When it comes to waterproofing with chemical grouts, application techniques will make or break a job. There is a lot of misinformation out there, so I encourage you to carefully evaluate the content below and make the most educated decision for your upcoming projects. (For further assistance with that decision, feel free to call our tech support team at 404-618-0438.)

Before we continue, I’d like to briefly let you know who I am and what I do. My name is Charlie Lerman (a.k.a. The Grout Geek). I was the Technical Field Services Manager at two industry-leading polyurethane grout manufacturers for 18+ years before joining Alchemy-Spetec as the Director of Technical Services – Leak Seal Division. My full-time responsibility is to take care of your questions and uncertainties concerning waterproofing with chemical grout and alternative options. So when is it best to use hydraulic cement? When should you use chemical grout? Let’s compare:

What is Hydraulic Cement? Key Features

Hydraulic cement is inexpensive and easy to apply but its benefits stop there. It is a surface patch that is primarily applied to the negative side. It has a weak adhesion and thus is applied in a groove or similar cut. It can be used to shut down low-pressure leaks. Being that it is cement it has a low tensile strength which means just like other types of cement it will be brittle when it is cured.

Chemical Grout Features

There are two primary types of chemical grouts when it comes to crack injection, each unique in its composition and makeup: (1) acrylics and (2) polyurethanes.

1. Acrylic grouts are free of suspended solids and have extremely low viscosity. The grouts can change from a liquid to a solid in a controllable gel time ranging from 3 seconds up to 10 plus hours. The lifespan of acrylic grouts is estimated to be between 50-300 years depending on the method and application utilized. Acrylic grouts are hydrophilic, have about 500% elongation, and are only about 20 cps. These properties make them ideal for injecting hairline cracks. Alchemy-Spetec's Spetec AG200 acrylic injection resin is NSF 61-5 certified for contact with drinking water.

2. Polyurethane grouts can be grouped into two types: hydrophilic and hydrophobic. Hydrophilic grouts are usually single component formulations that react with water and cure to an expansive flexible foam or non-expansive gel requiring a moist/humid environment after curing. Hydrophobic grouts are expansive foams that require little water to react and can easily withstand wet/dry cycles. Hydrophilic foams expand 4 to 6 times their original volume, while hydrophobic foams can expand up to 40 times their original volume and may cure flexibly or rigidly. Alchemy-Spetec offers many polyurethane resins that are NSF 61-5 certified for contact with drinking water. The lifespan of polyurethane foam is estimated to be approximately 70+ years.

Both acrylic and polyurethane chemical grouts are injected into cracks or joints and thus are not considered a negative side waterproofing even though they are often applied from the negative side. Acrylic and flexible polyurethanes are designed to shut down active leaks and, because of their high tensile strengths, they can withstand the movement of a dynamic crack or joint. Because they are full-depth repair materials, they can also encapsulate rebar and thus help prevent corrosion, spalling, and thus structural failure.

Applications: When, Where, and Why

I cannot emphasize enough how helpful it is to speak with an experienced grout consultant and/or an experienced contractor when faced with the need to stop leaks or control inflow and infiltration. If you are looking for installation recommendations, a knowledgeable grout manufacturer should be consulted to assist with proper grout selection and installation methodology. I am available to assist with your next project. Call Alchemy-Spetec at 404-618-0438 and ask for the Grout Geek!

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Sealing Joints with Grout and Oakum

Whether injecting with a pump or a cartridge, it's always helpful to have AP Oakum on hand. Liquids will take the path of least resistance and oakum is very adaptable for controlling them. For example, joints are typically easier to inject than cracks, and precast joints are about as easy as they come in regards to injection work. They are also very common routes for water infiltration, whether in manholes, culverts, vaults, and tunnels. Since joint injection does not require the consistent pressure provided by electric injection pumps, you can often make these repairs with cartridges instead.

Simple and Effective Leak Seal Method

Time and time again, it is easy to look like a hero with nothing more than a cartridge of Spetec PUR F400, a handful of AP oakum, and a flathead screwdriver. Lastly, be confident. Don’t confuse high-flow leaks with high-pressure. When you're working less than 20’ below grade, you are only dealing with a few psi of pressure even if it is a high-volume leak.

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Sealing Steam Leaks with Polyurethane

One of the most high-tech veneer manufacturing companies in the United States chose Alchemy-Spetec to train their maintenance techs to stop a steam leak in their facility. You heard that right. Not liquid water, but steam leaks! Prior to milling the veneer, they heat the logs in a bank of steam vaults. Rather than tearing down/rebuilding these cracked, leaking vaults they opted to inject the cracks with Spetec PUR F400, a hydrophobic flexible polyurethane grout. Replacing the vault would not only have been a lot more expensive, but it would also have resulted in a costly interruption to their milling process. No one likes downtime.

Polyurethane Leak Seal Training

Saturday is the one day of the week that the vaults are offline, and that is when I conducted the complimentary field training for their employees, who had never done any injection work before. Within a few hours, they understood how to handle the grout, how to use the grout pump, and how to accomplish their injection work. They can now self-perform their crack injection as needed.

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I was a Machinist Mate in the Navy and thus almost all of my training was mechanically focused. One class I had was Electrical Theory for Mechanics. The quick summation by the Senior Chief instructor for it was "Electricity is magic and when the smoke comes out the show is over." Being on a submarine it was deemed a good thing to keep water and electricity separate. My first time ever using polyurethane chemical grouts was on a group of sixteen conduits entering a below-grade mechanical room. While electricians may understand the "magic" of electricity they often fall short as waterproofers. Combined with the fact the numerous electrical cables coming through a conduit can be notoriously hard to waterproof and it is a recipe for leaks and electrical problems. In this post, I'll share step-by-step instructions, along with a couple of photos from a recent job one of our customers completed in a San Francisco condo complex.

Oakum soakem is a kindergarten-skill level procedure that makes waterproofing these types of penetrations easy. I refer to this as fingerpainting with chemical grouts.

1. For PVC and HDPE pipe roughing the surface will increase the mechanical bond and is recommended.
2. Wet the application area.
3. Soak oakum in either Spetec F400, GT500, or GT380 resin until saturated.
4. Pack soaked oakum into pipe joint to be sealed. If necessary, pack multiple layers. Ensure it is under compression.
5. Allow grout to cure.

Often this is all that needs to be done, but it can be followed up with injection to fill the conduit if required.

1. Stab injection needle through the cured grout and oakum plug.
2. Inject grout.

Photo: Contractor on a recent job in San Francisco, addressing multiple conduit leaks with electric injection pump, a pail of Spetec PUR F400, and Oakum.

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