RFI Questions and Answers Sewage Lift Station Albany CA.pdf

a. Question: What are the parameters or operational requirements regarding bypass pumping? Are there any LOTO or shutdown related restrictions?

Answer: Yes, lock out tag out is required by the USDA, OSHA, and NEC on the main breakers feeding the pumps and control panel while performing work on/in the lift station and control panel.

b. Question: What is the maximum allowable time the wet well can be out of service?

Answer: The bypass is to redirect incoming waste to a manhole further downstream which will allow the work to be performed in the lift station without interrupting the waste disposal stream. This is a common practice for any type of work in manholes, lifts station, or piping where the flow cannot be interrupted during repairs and also a safe working environment practice.

c. Question: Are there drawings available for the existing installation area?

Answer: I am not aware of any drawing available onsite however realistically this is a very straight forward project and should not require drawings. The work is physically viewable by any contractor and if they have experience the plans would not be viewed.

d. Question: Can you provide the nameplate date or power rating of the existing pump?

Answer: No, it is submerged in waste and the existing name plates are not readable.

e. Question: What power is available for the new pump and control panel respectively?

Answer: There is an existing control panel in place which can be retrofitted for the installation of the pump controls as well as the installation of the Hydro Ranger. The existing breaker is located and fed from the emergency panel at the Western Annex Building Generator sub panel. The main Feed breaker is 208 v/ 30amp for the existing control panel.

f. Question: Both Hydro Ranger units and floats are mentioned in the contract documents.

HydroRangers use an ultrasonic level monitoring system which would seem to conflict with using float switches in the system. What is the intended control strategy involving these components?

Answer: There is only a need for one Hydro Ranger control panel. The primary level indicator for the Hydro Ranger is an ultrasonic level sensor, the redundant backup is the mechanical floats which an assurance the operating pumps will not burn up from ultrasonic level sensor failure. This is a common practice for systems on the WRRC facility and is in place on our other Hydro Ranger pump in the facility. Mechanical floats fail and ultrasonic level sensors fail from moisture on the lens, this is our solution to make sure the pumps are protected as the pumps are very expensive compared to adding additional floats and we do not have an unauthorized spill release of waste water. If the contractor has experience in the installation of the Hydro Ranger the question of conflict would not be a question.

g. Question: In what capacity is an exhaust fan incorporated?

Answer: A temporary manhole exhaust system as well as an LEL/O2/H2S continuous air monitor is required to work in confined space at all times to meet USDA and OSHA safety requirements. The USDA and OSHA considers all manholes and lift stations confined space.

h. Question: What existing exhaust ventilation is utilized in the current system?

Answer: There is no existing exhaust system.

i. Question: How much flow should we expect to be dealing with on Saturday & Sunday workdays and should we anticipate installing a temporary bypass during our work?

Answer: As the flow rate varies from high to low based on use the actual flow rate cannot be defined at any given time. The existing storage capacity will not handle the down time associated to this project. This is a mandatory requirement based on health, safety, and environmental concerns by the USDA. The bypass for each manhole should be a minimum of 3” using a pump that can handle solids commonly found in sewer systems. The bypass pumping system shall be setup with a primary and secondary float system so the pump can operate 24 hours a day for your anticipated time required to complete this project. This will assure minimal risk of failure and unauthorized releases.

All unauthorized releases as the result of work being performed for this project will be at the cost of the contractor to mitigate. All notices of violation and/or fines associated to an unauthorized release as the result of work being performed for this project will be at the cost of the contractor.

j. Question: Do you have a specification for the (4") check valves and ball valves to be used? (PVC, ductile iron, flanged, threaded etc.)

Answer: The valves and piping shall be constructed of ductile Iron specifically designed for waste water applications to allow solids and other materials commonly found in lift stations and produced from grinder pumps within lift stations to pass without compromising the intent of the check valves or ball valves. All ball valves shall be full port.

k. Question: Pages 5 & 6 of the specifications call out new ball valves and check valves to be installed under this project. Please provide a specification or any further details on the valves to be installed. Will flanged sch80 PVC valve: be acceptable?

Answer: No PVC is not acceptable. The valves and piping shall be constructed of ductile Iron specifically designed for waste water applications to allow solids and other materials commonly found in lift stations and produced from grinder pumps within lift stations to pass without compromising the intent of the check valves or ball valves. All ball valves shall be full port.