Romtec Utilities» Pump Station Components/Capabilities

Liners & Coatings Save Pump Station Concrete

Dave — Wed, 12 May 2010 14:31:21 +0000

Corrosion of unprotected concrete

Romtec Utilities offers PVC and fiberglass liners and epoxy coatings for the interior surfaces of concrete wet wells and vaults in our wastewater pump stations. These treatments help prevent damage to the concrete from gasses and liquids that may be present in the sewage. The most common concern is hydrogen sulfide gas emitted from municipal wastewater and the sulfuric acid that forms through a bacterially mediated process. A description of the process that causes degradation of concrete from sewage gas is copied from Wikipedia at the end of this article.

We meet your specs for concrete protection

Romtec Utilities works closely with municipal water/wastewater agencies and their civil engineers to develop specifications for concrete protection.

T-Lock heat weld process

Liners

The most common liner used in Romtec Utilities wet wells is Ameron T-Lock. This PVC material is cast into the interior surface of the concrete at the time the parts are being manufactured. Joints between sections of the wet well and where pipes enter and exit the wet well are heat welded in the field at the time of installation. Other types of liners are available on request. These liners form a permanent impervious barrier on all interior surfaces of the concrete wet well protecting it from corrosion and water incursion. The smooth surface also helps in keeping the wet well free of built-up solids. Romtec Utilities offers liners on all cylindrical concrete wet wells and various rectangular concrete vaults.

Epoxy coated wet well interior

Coatings

Epoxy-based coatings are also applied to the interior and exterior surfaces of the concrete underground vessels to prevent corrosion and water incursion. Tnemec and Raven brand coatings are frequently specified. Application of these materials can be done at the factory or in the field.

What exactly is going on here?

Wikipedia gives us this description of the bio-chemical process responsible for damage to concrete wastewater infrastructure:

“Biogenic Sulfide Corrosion is a bacterially mediated process of forming hydrogen sulfide gas and the subsequent conversion to sulfuric acid that attacks concrete and steel within wastewater environments. The hydrogen sulfide gas is oxidized in the presence of moisture to form sulfuric acid that attacks the matrix of concrete. The effect of sulfuric acid on concrete and steel surfaces exposed to severe wastewater environments can be devastating.”

“Fresh domestic sewage entering a wastewater collection system contains an abundance of sulfates, SO₄^2-. In the absence of dissolved oxygen and nitrates, these sulfates are reduced by sulfate reducing bacteria (SRB), identified primarily from the obligate anaerobic species Desulfovibrio, to form H₂S via a complex pathway of biochemical reactions.”

“Once the H₂S gas diffuses into the headspace environment above the wastewater, a sulfur oxidizing bacteria (SOB), primarily genus Thiobacillus aerobic bacteria, which colonize on pipe crowns, walls, and other surfaces above the waterline in wastewater pipes and structures, metabolize the H₂S gas and oxidize it to H₂SO₄. This oxidizing process can take place where there is an adequate supply of hydrogen sulfide gas greater than 2 ppm, high relative humidity, and atmospheric oxygen.”

Valve assembly location – 3 options makes a difference

Dave — Thu, 06 May 2010 17:51:38 +0000

Valve assemblies in Romtec Utilities pump stations

Romtec Utilities pumping systems include the complete valve assembly between the pumps and force main. The basic valve assembly includes a check valve and a plug (isolation) valve in the discharge line from each pump. But that’s about it for basics, because each pump station has unique requirements for the valves and where they are located. Depending on various factors, the valve assembly can be located within the wet well, within a separate underground vault or above ground within an enclosure or right out in the open.

In-well valves – For submersible pump stations, reduced cost is an important factor in locating the valve assembly inside the wet well. Less pipe, fewer fittings and no underground vault or above ground enclosure are required, thus reducing cost.

Sufficient space inside the wet well can be a factor; the valves have to fit in the vertical pipe riser. The pre-assembled manifold with valves and piping for one, two or three pump systems can be quickly lowered in place, fitted to the pump discharge elbows and secured with brackets to the wet well.

Consideration must be given to how to maintain valves and pumps when the valves are located inside the wet well. Confined space safety requirements add some maintenance costs, so it is very advantageous to have less frequent valve maintenance. This is partly why pumping systems with in-well valves are often specified for stormwater or clean water rather than municipal wastewater since the hazard of entering the wet well to maintain valves is somewhat lessened. Sewage lift stations with in-well valves are often equipped with grinder or chopper pumps, because there is less potential for damage or clogging of a valve when solids are macerated, thus reducing the potential for valve maintenance inside the wet well.

Underground valve vaults – Most Romtec Utilities pump stations are supplied with an underground valve vault with pre-assembled valves and piping tested to 100 psi. The complete unit is delivered to the project site, positioned near the wet well and connected to the discharge pipes leaving the pumps. Prefabricating the valve assembly inside an underground concrete or fiberglass vault offers many advantages:
1.   Protection from freezing and security for equipment
2.   Fast installation without expensive field assembly
3.   Safe valve operation and maintenance without entering confined space
4.   Space in vault for other equipment: emergency pumping port/pig launcher, pressure sensors, etc.

Above-ground valve assemblies – In climates where freezing is not a factor, valves can be located above ground without insulation. In cold weather areas, above-ground valve assemblies must be fitted with insulating jackets.

Romtec Utilities offers a variety of valve assemblies with precast concrete pads ready for placement at the project site. Discharge pipes leaving the wet well are field fitted to the valve assembly. Various kinds of pumping systems often use above-ground valves:
1.   Industrial plants frequently prefer the simplified operation and maintenance offered by above-ground valves.
2.   Vertical turbine pumps are often fitted with above-ground valves.
3.   Emergency pumping systems generally have the valves exposed for quick access.

Gimme Shelter – pump station control shelters and buildings

Dave — Tue, 04 May 2010 14:33:45 +0000

Romtec pump station control shelters and buildings

Consider including a shelter or building in your pumping system design

Many lift stations need a weather/shade shelter or building to protect the control panel and to provide convenience and safety for operators.

Romtec Utilities partners with our sister company, Romtec, Inc. for design, supply and installation of steel shelters and solid concrete buildings to protect pump station controls. Together, the two companies provide a one-stop shopping approach to building a system complete with lift station and protective structure.

STEEL SHELTER - A Romtec powder coated steel shelter provides cooling shade for the pump station control panel and can be the most cost effective way to reduce the operating temperature inside the panel enclosure. It also gives weather protection to components anytime the enclosure must be opened. Operators don’t mind the shelter from blistering summer heat and winter precipitation either.

Romtec building houses generator

CONCRETE BUILDING – A Romtec concrete control structure can add a measure of safety and security to any pump station, by putting the electrical controls, generator and odor control equipment behind a locked door. Besides security, several other factors can play a role in choosing to house the above-ground equipment inside a building:

Aesthetics - Subdivisions often prefer to put the above-ground equipment inside a building and out of sight.
Sound Attenuation - Residents might not appreciate the sound of the standby electrical generator when it operates.
Municipal Standards - Some sewer agencies require a shelter or building for every pump station.
Building Codes - Some state and local codes may require a structure.
Operator Convenience & Safety – During harsh weather a clean, warm building makes operation and maintenance of the pump station easier and safer, for both workers and equipment.

THE COMPLETE PACKAGE - All necessary heating, ventilation, lighting and safety equipment are included in the complete Romtec pump station building. The turnkey solutions provided by both Romtec Utilities and Romtec, Inc. include professional design and architecture/engineering services valid in all 50 states.

Operational training

All structural, mechanical, electrical and communications components are integrated into complete pre-engineered systems. The complete pumping system arrives at the project site in a coordinated delivery, ready for fast and efficient installation and start-up. The entire installation, including a steel control shelter or concrete building, can be done in days rather than months, as can be the case with site-constructed pump stations. Romtec Utilities staff conducts extensive operation and maintenance training for the water/wastewater agency’s operation and maintenance personnel. Purchase contracts are available through the GSA and in various states, providing substantial discounts plus the convenience of a no-bid procurement process.

Fiberglass Advantages

Dave — Fri, 02 Apr 2010 17:34:48 +0000

12' dia. prefabricated fiberglass wastewater pump station

Romtec Utilities’ complete sewage pumping systems are available with wet wells and vaults of either fiberglass or concrete. The high-quality Xerxes fiberglass underground tanks are delivered to the job site fully assembled and ready for pipe and pump installation. Here are some of the advantages of fiberglass:

Complete one-piece structures require no field assembly. Pre-assembled fiberglass wet wells are ready to receive influent and discharge pipes, submersible or dry pit pumps and liquid level sensing devices.
One-piece fiberglass vessels up to 12 feet diameter and 40 feet long can be shipped to any project location.
Tanks have no joints to be sealed, so there is no potential for groundwater incursion.
Unique rib design makes wet wells more resistant to uplift the deeper the tank is placed underground.
Romtec Utilities factory assembled and tested valve vault
Tanks can be oriented either vertically or horizontally and fitted with a variety of pumps: submersible pumps, short set vertical turbine pumps and dry pit pumps in horizontal or vertical configuration.
Wet well’s truncated base with sloping sides helps prevent build-up of grease and other solids.
Fiberglass is not degraded by the hydrogen sulfide gas present in sewage, and it will not break down from exposure to petrochemicals, acids or caustic fluids. No additional sealing or coating of the fiberglass surface is required.

Click here to read more about recent installation of a Romtec Utilities-Xerxes prefabricated fiberglass pump station.

Distribution warehouse gets submersible sewage pump station

Dave — Wed, 24 Mar 2010 03:37:50 +0000

Distribution warehouse pump station collects combined sanitary sewer, storm runoff and, potentially, water from the building's fire suppression sprinklers.

Pumping system handles combined sanitary sewer, stormwater and potential fire suppression system water.

Romtec Utilities recently supplied a sewage lift station to the new 750,000 square foot Ferguson Enterprises Regional Distribution Center built on the site of a former US Navy facility in Stockton, Calif. Thomas Graham Civil Design Group was the project engineer and pm2i was general contractor.

Romtec supplied all structural, mechanical, electrical andtelemetry systems in the station, which features a 6’ dia. pre-cast concrete wet well to collect the combined sanitary sewer and stormwater runoff, as well as potential drainage from the building’s fire suppression sprinkler system. Also included in the complete system are a pre-assembled valve vault and all ductile piping, U.L. listed electrical controls and SCADA, and two ITT Flygt submersible pumps that discharge through a 4” dia. force main to the municipal gravity sewer.

Pump station odor & corrosion control with chemical feed system

Dave — Tue, 23 Mar 2010 17:28:18 +0000

Romtec Utilities chemical feed system for wastewater pump station

Sewage pumping systems are frequently fitted with chemical feed for odor and corrosion control plus worker safety.

Wastewater collection systems, including pump stations, can be subject to the build-up of hydrogen sulfide gas (H2S), frequently the source of unpleasant odor and a serious cause for concern due to potential corrosion of concrete exposed to the gas. Operator safety is an even more serious matter, since breathing high concentrations of H2S is potentially lethal.

Romtec Utilities supplies odor/corrosion control chemical feed systems in its complete pre-engineered wastewater pump stations. The chemical feed system allows various chemicals to be introduced into the pump station’s wet well or into the force main. Siemens BIOXIDE® solution is the chemical most frequently specified by Romtec Utilities for control of odor, corrosion and safety problems associated with hydrogen sulfide in wastewater collection systems.

Variable drip rates can be operator controlled or automatically determined by process flow rates to achieve desired odor reduction at optimum chemical usage. In Romtec’s lift station chemical feed systems, two chemical feed pumps are typically utilized to provide two points of chemical application and full redundancy of this important part of the sewage pumping system. Features of the odor control chemical feed systems offered by Romtec Utilities include: digital display of chemical feed rate; alarm for loss of chemical flow; complete pre-assembly of pumps, valves, meters and controls; and a large cross-linked polyethylene chemical storage tank.

Flow metering – an important pump station addition

Dave — Mon, 22 Mar 2010 23:45:44 +0000

Complete flow metering vault with sensor, and readout/transmitter

Consider flow metering for accurate measurement – Pumping systems are frequently required to measure the volume of fluid being pumped over a period of time. This is often the case if a subdivision or industrial site is billed by the municipal sewer agency for the amount of wastewater it discharges to the sewage treatment plant.

Calculating the flow – An easy and inexpensive way to get a reasonable estimate of the volume of wastewater being pumped is to “calculate the flow.” This is done by multiplying the volume of water pumped with each pump start by the number of pump starts over a period of time. The resulting number, the total volume pumped during the period, is useful for estimating purposes.

Flow metering – Flow metering may be necessary for proving the discharge volume. Romtec Utilities supplies a number of flow metering systems from leading manufacturers as part of our complete wastewater submersible pump stations. An electromagnetic flow meter is inserted in the force main after the check and plug valves. The meter and associated piping and valves can also be pre-assembled in a separate vault. To provide for maintenance of the flow meter without disabling the pump station, the assembly of piping and valves to bypass the flow meter are also located in the flow meter vault.

The flow readout and reporting device, usually located at the pump station control panel, receives electronic flow data and reports it to a display. Transmission of flow data to a remote computer terminal is also available.

Romtec Utilities offers pre-assembled flow metering vaults in our line of complete lift stations for wastewater, stormwater and industrial pumping. Designs are available with piping from 2″ to 10″ diameter and can deliver volume and flow measurements accurate to within 0.5%. The pre-assembled flow metering vault shown in the photo includes a pre-cast concrete vault with access hatch, an electromagnetic flow meter, ductile piping, isolation valves and a bypass line for continuous pumping anytime the meter is isolated for maintenance.