B09_Updated_Spec_Section_46_20_10_Addendum_April_9_2024_Amd3_0003.pdf
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- Attached to
- WRST 248940 - Replace Deficient WTP/Systems.
- Solicitation number
- 140P2024R0034
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This document is an addendum to a specification for a granular activated carbon (GAC) contactor system. The key details are:
The GAC contactor system is part of a water treatment process to remove free chlorine from pre-treated settled water before it enters a membrane treatment skid. The GAC contactor has a dechlorination capacity of up to 2 mg/L of free chlorine and an empty bed contact time of 7.3 minutes at a flow rate of 11.5 gallons per minute. The GAC vessel is constructed of composite fiberglass with a polyethylene inner shell, has a 4-inch threaded connections, and a maximum operating pressure of 150 psi. The GAC media is coconut-based activated carbon with specific physical and performance requirements.
This addendum is related to Solicitation Number 140P2024R0034 for the WRST 248940 - Replace Deficient Visitor Center / Headquarters Water Treatment System project, issued by the Department of the Interior National Park Service National Office.
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Addendum April 9, 2024 – Modifications to specification 46 20 10
2.4 GRANULAR ACTIVATED CARBON (GAC) CONTACTOR
A. Tag Numbers: GAC Contactor: T-2-2, Multiport Valve: FCV-2-2, Flow Control Orifice: FCO-2-
B. Granular Activated Carbon (GAC) vessel, multi-port flow valve, and appurtenances. GAC, vessel, valve, and appurtenances certified to NSF Standard 61.
C. Service: Pre-treated settled water (SW) flows through the GAC filled Tank T-2-2 for dechlorination prior to entering the membrane treatment skid. This treatment is provided because the AFC99 polyamide membranes are CHLORINE INTOLERANT.
D. Design:
1. De-chlorination Capacity of GAC Contactor: Up to 2 mg/L of free chlorine.
2. Empty Bed Contact Time: 7.3 minutes at a flow rate of 11.5 gpm.
3. GAC Media Loading: 4.0 6.0cubic feet.
E. Vessel.
1. Composite fiberglass construction, polyethylene inner shell with 4-inch threaded connections provided at the top (for flow valve installation) and at the bottom (to be provided with a plug to aid in media change-out).
2. Provided with stand, flow distributor, and fittings to accommodate 1-inch multi-function upflow control valve.
3. Maximum operating pressure: 150 psi. Safety Factor: 4:1. Minimum Burst: 600 psi.
4. Diameter: 18-21 inches. Height: nominal 65-inches, with base nominal 73-inches.
5. Capacity: 64-84 gallons (8.56 11.2 cubic feet).
6. Manufacturers known to meet the requirements set forth in this paragraph include, but are not limited to: Pentair Water Treatment Composite 18 x 65 21x62 COMP 4”T 4”B.
Structural, Composite.
F. Media:
1. Coconut activated carbon.
a. Iodine Number, minimum: 1050 mg/g
b. Ash, maximum: 4.0 wt%
c. Density: 0.48 g/cc
d. Hardness Number, minimum: 95
e. 12 US Mesh [1.70 mm], maximum: 5 wt%
f. <40 US Mesh [0.425 mm], maximum: 4 wt%
2. Manufacturers known to meet the requirements set forth in this paragraph include, but are not limited to: Calgon Carbon Corporation, OLC 12x40. Evoqua, Westates AquaCarb.
G. Multiport Valve (FCV-2-2):
1. Filter Control Valve with Electromechanical Timer.
2. Power: 110 V, 60 Hz.
3. Inlet/Outlet: 1-inch male NPT
4. Drain/Backwash: ¾-inch male NPT
5. Manufacturers known to meet the requirements set forth in this paragraph include, but are not limited to: Pentair Filtration and Process, Fleck 2750.
H. Flow Control Orifice (FCO-2-1):
1. Body: 304 stainless steel. Ends: 1½-inch male NPT.
2. Orifice: Buna N rubber. Retaining ring: Celcon M90.
3. Control Flow: 15 gpm.
4. Manufacturers known to meet the requirements set forth in this paragraph include, but are not limited to: Flomatic, Model CD900, CDT 1½ 15 17 gpm.
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