Plamen Koev Owner, 999 Godetia Drive, Woodside, CA 94062 Cell: 510-‐290-‐0752 August 31, 2012 Ryan Rucker Town of Woodside Building and Planning Department Re: Resubmittal on well development plans Dear Ryan, I hereby resubmit the plans for approval of the use of my well as a source for domestic water and fire protection. Here is an outline of the solution we are proposing with these resubmitted plans: 1. We will utilize no generator, since one is not required per WFPD 2. We will utilize three 2500 tanks, whose total volume of 7500 gallons exceeds the required storage for draft hydrant (5109 gallons), fire sprinklers (800 gallons), and domestic water (1250 gallons), a total of 7159 gallons. 3. The tanks will fill from the well by a Flint and Walling submersible pump (cut sheet attached). 4. For domestic water and fire sprinklers, we will utilize a variable speed pump by Flint and Walling—the Commander Pro 75-‐19 (cut sheet attached). This pump will be submersed in one of the holding tanks. This is a variable speed, constant pressure pump that is specifically designed for domestic water and requires a much smaller pressure tank than a traditional pump. It supplies 30 gallons per minute at 60psi, exceeding the domestic and fire sprinkler requirements per attached calculations by Axiom Engineers. 5. We will utilize a single pump for domestic water and fire sprinklers that will supply the house through a single line thus ensuring that the water to the fire sprinklers cannot be turned off without also turning off the water to the house. 6. Even though we will have shared storage for the draft hydrant water, the fire sprinkler water, and the domestic water, we will guarantee dedicated water for the draft hydrant and dedicated water for the fire sprinklers as follows: A) We will position the pump high enough in the tank, so that at least 5109 gallons for the draft hydrant are inaccessible to the pump and are thus guaranteed to be available for the draft hydrant; B) The remaining 2391 gallons will be available through the pump for fire sprinklers and domestic water. To guarantee that 800 of those gallons are dedicated to the fire sprinklers and unavailable for domestic use, we will utilize a solenoid valve on the domestic water line, a float switch in the tank, and the flow switch on the sprinkler line, so that the domestic water line is closed if either: • The fire sprinklers turn on • The stored domestic water is exhausted.
In particular, the float switch in the tanks will be located so that at least 800 gallons of water sit below it and above the 5109 gallons for domestic water. The response to your comments are as follows. STRUCTURAL COMMENTS Questions 1-‐6: Please see the new plans and calculations by our engineer Ray Worley, addressing your questions. In particular, the compliance with ASCE 7-‐05, Section 15.7.6.1. is now demonstrated. The question about overturning is addressed and Simpson SET XP epoxy is specified. The R value is taken from ASCE 7-‐05 table 15-‐4-‐2. The factor of 1.33 is removed resulting in a larger 7/8” threaded rod being utilized instead. Question 7: The tanks will be located on the existing basement concrete mat slab, which is 18” thick—the following detail is from the approved Sheet S2.
The thickness of the slab is 18” per approved plans, sheet S11, detail 12:
ADDITIONAL BUILDING, PLUMBING, AND ELECTRICAL COMMENTS 1. We will not utilize a backup generator The response to questions 2 and 3 is provided by Axiom Engineers: 2. Based on the 2010 CPC – Water supply fixture unit count = 43 WSFU. According to chart A-‐2, the corresponding flowrate is 25 GPM. Upon activation of sprinklers through flow switch at riser, solenoid valve closes domestic water supply (no additional capacity is required per NFPA 13D, section 6.3). 3. Yes, the calculations do account for the difference in height from the tanks location to the main living space and driveway. The details are as follows: • Tank location height = 759’ • Pump height = 759’ • Base of sprinkler riser = 768’ • Main living space height = 770’ • Driveway height = 769’ (Threaded connection height = 772’)
Domestic pressure: • Pressure required at last fixture -‐ 15 PSI • Pressure drop from pump to last fixture (+10% for fittings) – 15 PSI • Head pressure from pump to last fixture (elevation gain = 11’) ~ 4.8 PSI • Equipment (strainers, water heaters, etc) ~ 15 PSI • FS (10% of total) -‐ 5 • Total required: 54.8 PSI • Actual Supply pressure = 60 PSI Fire pressure: • Pressure required at base of fire riser -‐ 40 PSI • Pressure drop from pump to fire riser (distance = 100’, 1 ½” pipe, 30 GPM,+10% for fittings) = 6’ loss per 100’ ~3 PSI • Head pressure from pump to base of riser (elevation gain = 9’) ~ 4 PSI • Total required: 47 PSI • Actual Supply pressure = 60 PSI 4. The proposed 2500 gallon water tanks, manufactured by NORWESCO are dual purpose for both domestic and fire protection and have been approved by San Mateo County Environmental Health per the comments in your letter by Stanley Low. 5. The proposed tanks are manufactured by NORWESCO. Their catalog number is N-‐ 40631. The link to the tank’s specs are at: http://www.norwesco.com/page.cfm?menu=35 and the cut sheet is attached to this submittal. 6. We have updated sheet W-‐1 to show the septic system, septic lateral, and the leach fields. The location of the well meets the San Mateo County minimum distance requirements to the above. That location was approved by San Mateo County prior to well permit issuance. 7. The three 2500 gallon water tanks will be located on the existing basement mat slab. The pump that will supply water for domestic purposes and the fire sprinklers will be submersed in one of the tanks. The only equipment that will need to be installed outside the tanks is a 4.8 gallon expansion tank. Since this is a very small item to be installed somewhere along the water line in accordance with the manufacturer’s specifications, we would like to ask for leeway on your part to field determine the best location for it. 8. We have revised sheet P0.2 to show three tanks. These will be three 2500 water tanks with a total volume of 7500 gallons, exceeding the 7159 gallon requirement. 9. The P-‐1 pump was specified on sheet P0.2. It’s a Flint and Walling Commander Pro 75-‐ 19 pump, whose cut sheet is attached to this letter. 10. We will utilize two 4-‐inch Flint and Walling submersible pumps. A deep well one to pump the water out of the well and into the storage tanks, and the other one to pump the water from the storage tanks. Both measure 3 7/8” in diameter and about 28” in
height. The cut sheets are attached to this resubmittal and the pump specs are as follows: a) Well pump: Flint and Walling 1HP submersible 4” pump, model 4F05S10. This is a 1HP, 230V, 8A single phase pump. b) Domestic/fire sprinkler pump: Flint and Walling 4” submersible pump, model CP75-‐ 19. This is a 1½ HP, 11 Amp, variable-‐speed pump designed specifically to provide near constant pressure for domestic water applications. 11. Per the attached cut sheet and the relatively low amperage of both pumps, we will install each one of a dedicated circuit with a 15 Amp breaker. The line to the pump inside the well will be two (live, 230V) multistranded 10 Gauge wires and a ground inside a 1” Schedule 40 PVC conduit. The line to the domestic/fire sprinkler pump will be on a dedicated 10A circuit, properly wired inside the house with two 12 gauge wires and a ground.
12. Please see the revised sheet P0.2 by Axiom engineers with detailed legend of symbols. 13. Domestic supply branch line take off is before the sprinkler riser, the sprinkler riser has a check valve in the vertical rise (which has already been installed and inspected by WFPD). The following detail is from the approved sprinkler plans, sheet FP-‐2:
14. We have included a 4” back-‐check valve as per your comments, see sheet P0.2. 15. See the attached thrust block detail, drawing P0.3 16. All new equipment is to be installed on the existing basement concrete pad. No new impervious surfaces will be required.
Thank you for your detailed attention to this matter. Please give me a call at 510-‐290-‐0752 should you have any questions. Sincerely, Plamen Koev Attachments: 1. Four inch submersible pumps—we’ll utilize the 4F05S10 pump. 2. Commander Pro 75 systems cut sheet—we’ll utilize the CP 75-‐19 pump. 3. NORWESCO 2500 gallon tank cut sheet 4. New sheet P0.3 for thrust blocks 5. Calculations by Axiom Engineers 6. Revised sheet P0.2 for the mechanical design 7. Revised calculations by our engineer Ray Worley 8. Revised sheet W-‐2 showing tank anchorage 9. Revised sheet W-‐1.