Manhole Rehabilitation

SpectraShield installed by SpectraTech is a great solution to the problem of aging and deteriorating wastewater infrastructure.  Wastewater collection systems contain more than 20 million manholes.  Of this total, 4 million are 50 years old or older and another 5 million are 30 to 50 years old.  The U.S. Environmental Protection Agency estimates that approximately 50 percent of the oldest and 30 percent of the 30 to 50 year old manholes (approximately 3.5 million combined) are suffering from serious structural decay and are in need of immediate replacement or rehabilitation.  Unlined concrete manholes have many deficiencies that our solution corrects better than any of our competitors products.  The problems are:

  • Infiltration
  • Corrosion
  • Structural Fatigue

Infiltration:
Traditional techniques to stem the tide of wastewater infiltration have concentrated on expensive Cured-In-Place (CIP) pipe lining but more recent studies show that manholes and other structures account for 30-50% of total water infiltration.  Water infiltration in structures can occur at casting joints, risers, precast manhole joints, mainline and lateral stubouts and fatigue cracks in both brick and precast manholes.  When you compare the cost of rehabilitation to the percentage of infiltration for the average system you will find that at just 30% of total infiltration, manhole rehabilitation is three times for cost effective than CIP pipe linings.  At just 2.5 gallon per minute of average water infiltration our solution will typically pay for itself with reduced wastewater treatment costs in less than a year.  The Stress Skin nature of our solution seals all of these sources of infiltration permanently.

Corrosion:
Sulfide-rich wastewater, a warm, humid environment and long retention times create the perfect conditions for microbiologically induced corrosion (MIC). MIC, a result of an acid-producing bacteria known as Thiobacillus, is the principal cause of corrosion in a municipal sewer system. These microorganisms metabolize elemental sulfur oxidized from H2S sewer gas and produce sulfuric acid as a waste product which then attacks the substrate. This sulfuric acid can quickly destroy ordinary concrete-based materials in a municipal sewer system.  It is important to note that research shows that these acidic compounds are almost non-existent in the wastewater itself.  It is the vapors that are airborne in the structure and combining with the condensate on the structure walls and humidity in the atmosphere that are the primary cause of concrete corrosion.  Sealing of the concrete below the flow level of the structure adds minimal protection at a significant increase in cost and complexity of deployment.  The Polyurea elastomer used for layers one and three are inert in the presence of sulfuric acid and completely seal the concrete, brick and mortar from the acidic compounds and with a 100-year design life our coatings are likely to outlive the cities they are installed in.

Structural Fatigue:
Fatigue from traffic loading, shifting and expanding soils, temperature variation and ebb-and-tide ground water loading seriously weaken manholes and other sewer system structures. Over time, ground water will find its way through fatigue cracks and weakened joints, leading to further deterioration of the structure. Fallen bricks and mortar can block the sewer flow, and may eventually lead to collapse, seriously endangering the surface and surrounding environment.  These same elements are at play on our competitors who use a variation on Shotcrete as they are also prone to structural fatigue over time.  The Stress Skin design of our solution reinforces the structures they are applied to and because this design is based composed of elastomer in layers one and three with closed-cell foam in between our solution can flex very slightly with the structure instead of cracking.

Conclusion:
The polyurea elastomer in layer one bonds securely to the substrate and seals the structure from water infiltration.  Layer two is a closed-cell foam that smooths the inside of the manhole and fills any voids.  Layer three is another layer of polyurea elastomer that seals the inside of the manhole from any corrosion from airborne sulfuric acid compounds.  We seal the structure from flow level to casting and solve the above issues permanently, and with a 100-year design life and 10-year warranty you will never have to worry about manhole rehabilitation again.  We can seal a typical 7-foot deep structure in less than an hour with no digging, minimal traffic disruption and a warranty that is unmatched in the industry.  Contact us today so we can answer any questions and personally show you how SpectraShield installed by SpectraTech can solve your water infiltration, sulfuric corrosion and structural fatigue problems.