Questions_answered.docx

1) What is the water used for and what are the daily requirements? The RFQ calls for a single softener. A single softener will not supply a continuous flow of water when it’s regenerating. A softener takes approximately 1.5 hours to regenerate. We need to make sure the water supply does not exceed 700 gallons in 1.5 hours. We will have to lock out the RO when the softener is regenerating.

The water is used for evaporative cooling in the greenhouse. The daily requirements vary. See Basis of Design in the attached drawing set.

2) The RFQ calls for two RO Generators each rated for 10 gpm. Are these units to operate in parallel or alternating? If the unit operates in alternating where one unit is on line and the other is in standby, then the feed flow to the RO is 13.3 GPM at 75% recovery. In this case, a single, 24x72 carbon filter is effectively sized. If both units operate in parallel to produce 20 gpm, then the feed flow required is 26.6 gpm. The carbon filter is too small to support this flow rate.

Parallel. The selected carbon filter indicates a flow capacity of 33 GPM.

3) Since a softener is used, is there a reason antiscalant is required?

Control silica levels.

4) I am assuming the calcite filter is used to boost the pH of permeate. Is the calcite filter installed between the RO and Storage Tank or after the Storage Tank? Keep in mind that the calcite will add minerals back to the water, which will increase the conductivity. This is why I would like to know the application.

See attached drawing set for orientation.

5) Under section 2.3 DUPLEX REVERSE OSMOSIS (RO) GENERATORS

Item B. NEMA 4X is stated then in Section 2.10 CONTROL PANEL AND ASSOCIATED CONTROLS A. UL Listed NEMA 4 Enclosure - is NEMA 4 acceptable or is NEMA 4 X required?

NEMA 4 is acceptable

Item C. Pumps do not have integral VFD’s in Section 2.9 DUPLEX PUMPS I. Provide integral VFD. We are assuming the VFD is required – is that correct?

VFD’s are not needed on the RO generator, but are on the duplex distribution pumps.

6) Antiscalant Pump is specified as an LMI with a 35 Gallon day Tank. What is the intended flow (GPH) of the required pump. This will depend several factors: dosage of antiscalant to be used and dilution of the antiscalant to be used.

20 GPH

7) Par 2.9(A) states "304 stainless steel casing, shaft impellers", however the Grundfos PN in the schedule (CRE5-13 AN-FGJ-A-E-HQQE) refers to a pump with cast iron housing and SS impeller. Please clarify on desired materials for the duplex pumps and the RO high pressure pumps.

Provide pump as shown in the schedules.

8) Par 3.1B Mentions drawings and P&IDs. Are these items available?

Attached.

9) Has pilot testing been performed, or has a computer performance review been done for the feed water and the specified membranes? If so, is this information available?

Incoming water quality attached. No computer modeling or pilot testing has been completed.