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Manhole rehabilitation
SealGuard · Polyurethane grout
SealGuard II Dual Component Grout
A two-component, hydrophobic polyurethane grout for active, fast-moving leaks. Inject it through a drilled hole straight into the running water, and it reacts in 1 to 3 seconds to seal the leak path from the inside.
second reaction time at 70°F
1–3
stops leaks up to 50 gallons per minute
50 gpm
no packers, no catalyst to mix
No pump
Stops the water where it gets in
Inject it, don’t cover it. SealGuard II goes in through a 5/8″ hole drilled into the leak path. The two parts mix in the nozzle and react with each other, not with the water, which is why it sets in seconds even in a running leak. It foams into the crack or joint and sets into a firm, mushroom-shaped plug.
1–3 sec
Reacts in running water
Fast enough to hold in a high-flow leak that would wash out a slower grout.
No mixing
Mixes in the nozzle
The static mixer blends the two parts as you pump. No measuring and no buckets.
SealGuard II 600 ml dual cartridge
0%
Won’t shrink
It’s hydrophobic: it sheds water instead of absorbing it, so the cured grout doesn’t shrink as the area dries out.
Save the rest
Check-valve mixer
The patented check-valve mixer keeps grout from reacting back into the cartridge, so you can cap a partly used cartridge and finish it on the next leak with a new mixer.
Why crews switch to SealGuard II
Compared with a hydraulic cement plug or a pump-and-packer grout system.
No pump. No packers.
The mixer threads into the drilled hole and acts as the injection port. Your kit is a drill, a gun and a box of cartridges.
Nothing to measure
The two parts mix in the nozzle. No catalyst to dose and no buckets to clean.
Sets before it washes out
1 to 3 seconds at 70°F. Many single-component grouts with catalyst are rated in tens of seconds to minutes.
Your crew, not a contractor
In Leesburg, Virginia, a two-person town crew grouted 186 manholes in a reported 230 labor hours.
Pick by the job
All three are hydrophobic polyurethanes that cure without shrinking. The difference is speed and the job.
| SealGuard product | Use it for | Speed | Comes in |
|---|---|---|---|
| SealGuard II This page | Active leaks with fast-moving water, up to 50 gpm | 1 to 3 seconds | 600 ml dual cartridge, dual component gun |
| HyperFlex | Slow leaks and seeping cracks, joints and honeycombed concrete | About 30 to 60 seconds | 300 ml tube or 5 gallon pail, standard caulk gun |
| X-Seal | Sealing joints as you build or raise a manhole: sections, adjusting rings, frames | Cures in 15 minutes to 24 hours | 300 ml tube, standard caulk gun |
Filling voids behind a structure or an abandoned line? See Strong-Seal® Grout 250 and Grout 1,000.
Lining the structure once it’s dry? See the Strong-Seal® cementitious products.
Five steps to stop a leak
1
Inspect
Find the leak and clear loose debris from around it.
2
Drill
Drill a 5/8″ hole to cross the leak path. In walls 12″ thick or less, drill straight in about 4″ to 6″ above the leak. In thicker walls, drill at an angle to meet the leak path.
3
Set the mixer
Slide the nut over the static mixer, thread end first, and tap both into the hole until snug.
4
Load the gun
Pull back the plungers, load the cartridge upright, remove the end caps and thread it onto the nut.
5
Pump
Pump until the leak stops or the grout won’t take more. If grout washes out, pump slower, or pause until it reacts halfway down the mixer, then pump again.
Cold cartridges react slowly. Warm them in hot water for about 10 minutes before use. If water is spraying, pack the leak itself with burlap, rags or oakum first.
See it work
Real leaks, sealed with SealGuard II.
Before Water running from a leaking joint
After Sealed with SealGuard II
Groundwater pouring in at a pipe connection
Drilling into the leak path
On the truck
What to bring, and what to do when the grout doesn’t behave.
What to bring
- Hammer drill and a 5/8″ masonry bit, 18″ long; longer bits for thick walls
- SealGuard II cartridges, the dual component gun and spare static mixers
- Burlap, dry oakum or rags, a putty knife or screwdriver, and duct tape
- A bucket of hot water in cold weather, or 70°F water in hot weather
- Goggles, chemical-resistant gloves, coveralls or old clothes, hard hat and light
- A scraper and trash bags for clean-up, plus your confined-space gear
If it’s not working
| Problem | What to do |
|---|---|
| Reacts slowly | Cartridges are cold. Stand them in hot water for about 10 minutes. |
| Reacts too fast or sets in the mixer | Cartridges are too warm. Cool them in 70°F water. Keep pumping steadily; pausing more than a second or two can clog the mixer. |
| Washes out (water looks milky) | Pause until grout reacts partway down the mixer, then pump again. Pack the leak with burlap, rags or oakum. Drill the next hole farther from the leak. |
| Leaks out around the mixer | Wrap a rag or burlap around the mixer, tape it, and tap it back into the hole. |
| Won’t go in, or no water comes back out of the hole | The hole likely missed the leak path. Drill another hole at a shallower angle. |
| Keeps taking grout, nothing shows at the leak | You may be filling a void behind the wall. Stop. Re-drill closer to the leak and pack the leak well. |
| Hit rebar | Move over and drill again. |
Don’t force it. Forcing can push grout back into the cartridge or break the gun.
What a leak costs
Small leaks add up fast
Groundwater that leaks into a sanitary sewer is pumped and treated along with the sewage. Set the leak rate and your cost to treat a thousand gallons to see what one leak costs in a year.
Cost to treat 1,000 gallons
gallons a year
a year to treat
Gallons a year = gpm × 525,600. U.S. EPA figures, as reported by MSW Magazine (2018), put wastewater collection and treatment at $2 to $5 per thousand gallons. Assumes a steady leak all year; real infiltration rises and falls with groundwater and rain, so use your own flow data where you have it.
Field results
As reported by SealGuard Inc. and customers.
Pittsburgh, Pennsylvania
Over 200 gpm, stopped in under an hour
A precast manhole in the Monongahela River was leaking more than 200 gpm at a joint about 8 feet below the waterline. Divers had tried for two days. A SealGuard Inc. crew packed the joint with oakum and stopped the inflow with 14 SealGuard II cartridges, in under an hour in the manhole.
Source: SealGuard Inc. case study
Marion, Indiana
A 50+ gpm leak at a pump station
Water was pouring in where the wall was cored for the sewer pipe. One SealGuard II cartridge slowed it by nearly 80%, a second cut it to a trickle, and a tube of HyperFlex finished it.
Source: customer story
Leesburg, Virginia
186 manholes, one town crew
Starting in 2004, a two-person town crew grouted 186 manholes with SealGuard in a reported 230 labor hours and stopped 531 gpm of infiltration, which the town reported as reclaiming 17% of its treatment plant’s capacity.
Source: customer story
What to order
| Part number | Description |
|---|---|
| SG-6KITST | SealGuard II starter kit: 6 cartridges, 6 static mixers, a dual component gun, goggles and gloves |
| SG-RE6 | SealGuard II reorder kit, 6 cartridges with mixing tips |
| SG-RE12 | SealGuard II reorder kit, 12 cartridges with mixing tips |
| SG-MXP6 | SealGuard II static mixers, 6 pack |
| SG-MXP12 | SealGuard II static mixers, 12 pack |
| SG-CGUND | Premium dual component caulk gun |
| SG-CGUNPN | Pneumatic dual component caulk gun |
Each cartridge is 600 ml, two 300 ml sides. Reorder kits include one mixer per cartridge; buy mixer packs for partial cartridges and spares. The manual gun covers most jobs; the pneumatic gun runs on shop air and saves your hands on big jobs.
Watch it stop a leak
SealGuard II injected into an active leak in a brick and concrete structure.
Technical data
Specifications
| Type | Two-component hydrophobic polyurethane injection grout |
|---|---|
| Packaging | 600 ml dual cartridge |
| Reaction time | 1 to 3 seconds at 70°F |
| Leak rate | Stops leaks up to 50 gallons per minute |
| Shrinkage (ASTM D2126) | 0% at −20°F, 1 day |
| Viscosity at 68°F | Side A 200 cps, side B 300 cps |
| Specific gravity at 60°F | Side A 1.23, side B 1.04 |
| Solids | 100%, no solvents |
| Color | Amber |
| Density, free rise (ASTM D1622) | 8 lb/ft³ |
| Compressive strength (ASTM D1621) | 900 psi |
|---|---|
| Tensile strength (ASTM D638) | 200 psi |
| Shear strength (ASTM D732) | 190 psi |
| Drill size | 5/8″ |
| Equipment | Dual component caulk gun, manual or pneumatic, with SealGuard II static mixers |
| Storage | Store under 80°F and keep sealed until use. The material reacts with moisture. |
| Shelf life | Two years minimum, unopened |
| Transport | U.S. D.O.T. unregulated, Class 55 |
| Typical structures | Manholes, vaults, meter pits, culverts and other concrete, brick or stone structures, above or below grade |
For engineers and specifiers
What goes in the submittal
Chemical grouting of sewer manholes is covered by ASTM F2414, Standard Practice for Sealing Sewer Manholes Using Chemical Grouting, and by NASSCO’s Manhole Rehabilitation Performance Specification Guideline (2025). NASSCO calls for grouting only structurally sound manholes, after frame, cover and grade ring work is done. Values on this page come from SealGuard Inc. data. Ask us for the full package: data sheet, safety data sheet, NSF listing (HyperFlex), installation instructions and the chemical resistance chart. Send us your spec and we’ll show you where SealGuard fits.
FAQ
Common questions
SealGuard II or HyperFlex?
Use SealGuard II on fast, active leaks, where a slower grout would wash out. Use HyperFlex on slower leaks and seeping cracks and joints, where its slower reaction lets it travel farther before it sets. Some jobs use both: SealGuard II to stop the flow, HyperFlex to finish.
How big a leak will it stop?
Leaks up to 50 gallons per minute. On very fast leaks, pack the leak itself with burlap or oakum, then pump slowly so the grout has time to react.
Hydrophobic or hydrophilic grout?
Both are used to seal manholes. Hydrophilic grouts absorb water and can shrink if the ground dries out, then swell again when it’s wet. Hydrophobic grouts like SealGuard push water out as they cure and hold their size wet or dry, which suits manholes where the water table rises and falls. Check what your spec allows.
Can I adjust the reaction time?
Not with an added catalyst. You set the speed by picking the product: SealGuard II reacts in 1 to 3 seconds for fast leaks, and HyperFlex in about 30 to 60 seconds, so it travels farther. Temperature fine-tunes it: warm cold cartridges in hot water for about 10 minutes, or set them in 70°F water to slow them down. If your spec requires a catalyst-adjustable grout, ask us about an approved-equal review.
Does grout make the manhole stronger?
No. Injection grout stops water. It doesn’t add structural strength. NASSCO’s manhole rehabilitation guideline says to grout only structurally sound manholes, and to finish frame, cover and grade ring work first. If the walls are deteriorated, stop the leaks, then restore the structure with a Strong-Seal® liner.
How do I confirm the leak is sealed?
Look first: the joint or crack should be dry, with no running or weeping water. For a fully rehabilitated manhole, NASSCO’s guideline calls for a vacuum test to ASTM C1244. Many utilities also compare flow meter readings before and after the work.
How long does a grout repair last?
There’s no lab test that predicts the service life of injection grout, and we don’t make a lifetime claim. For planning, the U.S. EPA’s 2004 report to Congress, citing ASCE, lists 15 years for chemical grouting of manholes and 50 years for structural lining or replacement. Results depend on how fully the leak path is filled and the condition of the structure.
Polyurethane grout or hydraulic cement?
Use Strong-Plug® on small leaks at the surface that you can reach and hold until it sets. Use SealGuard II when the flow is too strong to hold a plug, or the water is coming through a joint or crack inside the wall. Use HyperFlex on slow leaks and seeping cracks.
How many cartridges will I need?
There’s no set number. It depends on how fast the water is moving and what’s behind the wall. In the field: a 50+ gpm pump station leak took 2 cartridges and a tube of HyperFlex (Marion, Indiana), and a precast joint leaking over 200 gpm took 14 cartridges (Pittsburgh). If a hole keeps taking grout and nothing shows at the leak, stop and re-drill closer.
Can I save a partly used cartridge?
Yes. When you finish, unscrew the nut and take the cartridge off quickly. The check valve in the mixer keeps grout from reacting back into it. Put the end caps back on and use a new mixer next time.
Does it hold up to chemicals?
SealGuard Inc.’s chart for cured polyurethanes rates resistance as excellent to water, brine, diesel, gasoline, motor oil, chlorine, wet hydrogen sulfide and 10% sulfuric acid. It rates concentrated nitric and sulfuric acid as not recommended, and acetone and MEK as poor. The chart doesn’t state a test method or exposure time. It’s in the documents below.
Is it approved for drinking water?
No. SealGuard II is not NSF/ANSI/CAN 61 certified. For potable water structures, use HyperFlex.
Can I line over it?
Yes. Stopping active leaks is the first step before lining a structure, because a cementitious liner needs a surface with no running water. Once the leaks are stopped, the structure can be lined with a Strong-Seal® liner.
How do I clean up?
Snap the used mixer or nozzle off with a sharp downward motion and scrape off excess once it’s cured. Cured foam and empty cartridges or tubes can go with ordinary construction waste. For anything uncured, follow the safety data sheet. Wear old clothes: cured grout doesn’t wash out.
What safety gear do I need?
SealGuard products are MDI based and can cause skin and breathing sensitization. Wear goggles, chemical-resistant gloves and coveralls, use respiratory protection where ventilation is poor, follow your confined-space procedures, and read the safety data sheet before you start. It lists other hazards too, and it’s in the documents below.
Documents
Sell sheets, installation instructions, safety data sheets and the chemical resistance chart, plus the Fernco Infrastructure catalog.
For distributors
Interested in carrying Fernco Infrastructure?
Fernco Infrastructure covers manhole, structure and pipe rehab with three product lines. Add them to your line card to serve municipal and contractor customers.
Got questions?
Fighting active infiltration or writing a spec? Our infrastructure team can help. Reach out, or find your Fernco rep.