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HomeMy WebLinkAbout1.03 As-built plan, structuralMahan Subdivision September, 2008 Tab4 As -Built Plan, Structural Engineering, Letter, and Cost Estimate MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 % Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com TIE TO EXISTING WATER SYSTEM FLOW —MP- o EXISTING PRESSURE FILTER REPLACE FILTER WITH 10 MICRON CARTRIDGE 3 4 3 4 4- 4 TIE TO EXISTING WATER SYSTEM FLOW UV LIGHT DISINFECTION RATED FOR 4 GPM MIN. NEW PRESSURE FILTER WITH 1 MICRON CARTRIDGE 1. GFI PROTECTED OUTLET 2. PRESSURE GAUGE 3. TEE 4. BALL VALVE PRESSURE FILTER ASSEMBLY NOT TO SCALE oen 0E/86/07 sou NO SCALE D IGICIR Chris NQL. o� ns 03117-m13-CFRIS Joe 501-081 Exhibit 1 POTABLE WATER SYSTEM IMPROVEMENTS Mahan Subdivision Approved for Construction MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 1/2 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5544 fx 970.945.5558 www.mounisincross-eng.com 6" PVC INTAKE PIPE 14' WEST WALL 14' Mr - 13.5" MIDDLE WALL 27" ={ VC OVERFLOW PIPE 0 6" PVC INTAKE PIPE • 25'3" 6" PVC FIRE HOSE CONNECTION NORTI I WALL UILDING EL HVATIONS CMU WALL 6" PVC OVERFLOW PIPE 25'3„ 8' 2" PVC TANK DRAINS L HAST WALL WATER STORAGE 10,052 GALLO\IS 2'5' VERT REBAR: #5 © 16" O.C. GROUTED CORES 0 QJ 17'3° PLAN VIEW SCAI,1-'z 6" PVC FIRE HOSE CONNECTION A zd. .2 O Go © o0 R co En cid Ly ...F., .ia z(,) -,:, 1■■N V 3 —ita> E•••w er isil c "9 E % c � o Z Z 3 � = iml ifj c 13 0 L; 2 O Z % -ti 1■■3Uw 3 ph 970 945.5544 fx 970.945.5558 www.mountaincross-eng.com 0, W COMMENTS DATE 07/08/08 SCALE 1 /2"=1 ' ENGINEER C. HALE DWG FILE MAHAN TANK JOB 501-001 SHEET August 5, 2008 Glenwood Springs Fire District Fire Marshal 101 West -8th Street MOUNTAIN CROSS ENGINEERING, INC. CIVIL AND ENVIRONMENTAL CONSULTING AND DESIGN Glenwood Springs, CO 81601 RE: Meeting Concerning Mahan — Final Plat Conditions Dear Ron: Thank you for meeting at the Mahan Water Tank on Friday August 1, 2008. This correspondence is an attempt to summarize the topics of discussion at that meeting. Garfield County has three conditions of approval for the Mahan project that involve the Fire District: 1. Provide fire department connection to 10,000 gallons of fire storage, 2. Incorporate a ,"wildfire mitigation plan" into the HOA documents to the satisfaction of the Fire District, and 3. provide Fire District Impact fees. 1. Regarding the water storage tank: the _Mahans had originally thought that there were two 5,000 gallons (10,000 gallons total) water storage tanks supplying the existing water system. The installer, contracted to construct the water line connection to the tanks, informed the Mahans and the engineer that the existing tank sizes were two 1,700 gallons. To remedy the shortfall, the Mahans constructed an additional 10,000 gallons of storage. This storage will be solely for fire suppression. Running water from the nearby stream will flow through the tank continuously. The tank and equipment was built and designed by others. As -built drawings were provided by Mountain Cross Engineering, Inc. The following comments were made concerning the tank construction: • The Fire District requested that the maintenance and repair of the tank be by the Home Owners Association. o The following items will be included in the Conditions, Covenants, and Restrictions. The tank shall be drained and sediment shall be cleaned from the tank yearly. Quarterly, the piping shall be flushed and cleaned. Equipment, tank and piping shall be visually inspected to verify soundness. Valves shall be operated. Vents and screens shall be cleaned and cleared. The ceiling, walls, and foundations shall be checked for corrosion, cracks and/or leaks. Any items identified as inoperable, broken, seized, or in any other way needing attention shall be repaired or replaced. • The Fire District requested that the Fire Department Connection (FDC) be accessible from the County Road instead of from the east end of the tank. o The connection will be switched from the east to the north side. This wilt avoid two 90' bends, allow the piping to drain to avoid freezing problems, and allow access from the County Road. The FDC will extend into the right -of way but terminate behind the drainage ditch of the CountyRoad. This will put the FDC within the right-of-way and within ten feet from the edge of the County Road. • The Fire District requested that the As -built construction be verified as structurally sound by a structural engineer. o The Mahans will hire a structural engineer to verify the strength of the as -built construction against the anticipated loadings. • • The Fire District requested that a hydraulic analysis be performed on the FDC to verify that the maximum vertical lift allowed is not exceeded during drafting of water. 826 1/2 Grand Avenue • Glenwood Springs, CO 81601 rat 1. nYn nA[ [CAA . ICA V• Gln DAL; {rzrQ • Ulllh/lF/mneenlainerncc-Ano rnirt Mahan Tank August 5, 2008 Page 2 of 2 o Attached is a hydraulic analysis of the connection from the tank to the FDC. The rate of drafting from the tank was 1,000 gallons per minute. The tank was modeled with tank full and with the water level one foot above the intake. The model shows a vertical lift of 1.5 feet required when the tank is full and a lift of 6.5 feet with the tank nearly empty. The elevation of theroject is near 6,800 feet_ The maximnt uallowablevertical-lift-at-an. elevation nf,000-%et-is-10-feet he -FDC- r^ nl appears4o-meet the -requirements. 2. The Wildfire Mitigation Plan and its incorporation into the Conditions, Covenants, and Restrictions was reviewed and is acceptable to the Fire District. 3. The Fire District verified that there are no Fire District Impact fees within this area of Garfield County. Therefore no money is due. Feel free to call if you would like to add or detract from the items in this Ietter. Also, please call if you have any questions or if any of the above needs further clarification. Thanks in advance. Sincerely, Mou�ntin Cross En F Chris Hale, PE Attachment nee , Inc. MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 IA Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.corn Scenario: Base Tank • FDC Project Engineer: Christopher F. Hale c:1...1501-001 mahan subdivisionkwatercadltank.wcd Mountain Cross Engineering WaterCAD v5.0 {5.00371 08105108 10:14:26 AM © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1665 Page 1 of 1 Scenario: Base Steady State Analysis Tank Report Project Engineer: Christopher F. Hale c'1-..1501-001 mahan subdivision\watercad\tank.wcd Mountain Cross Engineering WaterCAD v5.0 [5.0037] 08/05/08 10:13:30 AM © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 011 Label Zone Base Elevation (ft) Minimum Elevation (ft) Initial HGL (ft) Maximum Elevation (ft) Inactive Volume (gal) Tank Diameter (ft) Inflow (gpm) Current Status Calculated Hydraulic Grade (ft) Calculated Percent Full (%) Tank-7orl 6796700"k7g6.00 0.00 N/A ;,602-00 b,802.00- 1,000.00 t)raininc 6,802.00 100.0 Project Engineer: Christopher F. Hale c'1-..1501-001 mahan subdivision\watercad\tank.wcd Mountain Cross Engineering WaterCAD v5.0 [5.0037] 08/05/08 10:13:30 AM © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 011 Scenario: Base Steady State Analysis Pipe Report Label Length (ft) Diameter (in) t Material Hazen- Williams C DischargtJpstream (gpm) Structdarownsteam Hydraulic Grade (it) Structur@ressure Hydraulic Grade (ft) Pipe Headloss (ft) Headloss Gradient (ft/1000ft) Velocity (ftis) b"i'VC-Yip i.i „fit' ii .,:02 30- 6;798.35 345 13&14--1135 Project Engineer: Christopher F. Hale c:1...1501-001 mahan subdivisionlwatercadltank.wcd Mountain Cross Engineering WaterCAD v5.0 [5.00371 08/05/08 10:13:47 AM © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1 Scenario: Base Steady State Analysis Junction Report Project Engineer: Christopher F. Hale c:1...1501-001 maban subdivisionlwatercadltank.wcd Mountain Cross Engineering WaterCAD v5.0 [5.0037] 08/05/08 10:22:38 AM © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1 Label Elevation (ft) Zone Type Base Flaw (gpm) Pattern Demand CalculatedHydraulic (gPm) Calculated Grad(feet (ft) Pressure H20) FOC 6,800.00 Zone -1 Demand 1,000.00 Fixed 1,000.00 6,798.55 -1.45 Project Engineer: Christopher F. Hale c:1...1501-001 maban subdivisionlwatercadltank.wcd Mountain Cross Engineering WaterCAD v5.0 [5.0037] 08/05/08 10:22:38 AM © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1 Scenario: Base Steady State Analysis Tank Report Label Zone Base Elevation (ft) Minimum Elevation (ft) Initial HGL (ft) Maximum Elevation (ft) Inactive Volume (gal) Tank Diameter (ft) Inflow (gpm) Current Status Calculated hydraulic Gradp (ft) Calculated Percent Full (%) -Zone-16;796:00-67796.06 lank >797-.00 6;802700' —0:00- X 1T000TO z 9; OO 171~ Project Engineer: Christophe ca.._\501-001 mahan subdivisionlwatercadltank.wcd Mountain Cross Engineering WaterCAD v5.0 08/05/08 10:15:02 AM © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Pa Scenario: Base Steady State Analysis Pipe Report Label Length (ft) Diame ter (in) Ma teria 1 Hazen -i Williams C Discharg Upstream (gpm) Structrffwnstream Hydraulic Grade (ft) Structui'ressure Hydraulic Grade (ft) Pipe Headloss (ft) Headloss Gradient (W1000ft) Velocity (Ws) . -, •Ip .11 .,/ -. 1.1 ,111.11 , • .11 • • . —3745-1-387121 11.35 Project Engineer: Christopher F. Hale c:\ ..1501-001 mahan subdivisionlwatercadltank.wcd Mountain Cross Engineering WaterCAD v5.0 [5.0037] 08/05/08 10:15:22 AM © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1 Scenario: Base Steady State Analysis Junction Report Label Elevation (ft) Zone Type Base Flow (gpm) Pattern Demand Calculated+iydraulic (gpm) Calculated Gradefeet (ft) Pressure H20) FOC 6,800.00 Zone -1 Demand 1,000.00 Fixed 1,000.00 6,793.55 -6.44 Project Engineer: Christopher F. Hale c:1...1501-001 mahan subdivisionlwatercadltank.wcd Mountain Cross Engineering WaterCAD v5.0 [5.003T 08/05105 10:21:27 AM 0 Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1 Chris Hale, P.E. Mountain Cross Engineering, Inc. 826 1/2 Grand Ave. Glenwood Springs, CO. 81601 August 20, 2008 Re: Mahan Water Storage Tank Dear Mr. Hale; This letter documents the structural design investigation I have performed for the proposed Mahan Water Storage Tank Iocated at Black Diamond Mine Road, Garfield County Colorado. I understand that the tank will be used for firewater storage and will serve two private residences_ Construction I observed the tank on August 13, 2008 and found construction underway. The foundation and walls were constructed, piping was being set in place, and some coatings were applied to the interior of the tank_ Visual inspection showed CMU walls bearing on a concrete slab foundation. Reinforcing bars were noted to be placed vertically in the wall and spaced 16" o.c. All cells appeared to be grouted. No other structural details were exposed for inspection. Overall dimensions appear to be consistent with as built drawings prepared by your office. A subsequent discussion with the owner Chris Norris revealed that the foundation construction was a thickened edge slab on grade. Mr. Norris provided the following construction details. The slab thickness is 7" and the thickened edge perimeter footing is 30" wide x 10" deep. The footing section has (3) # 5 reinforcing bars. The slab portion is reinforced with #3 bars @ 15" o.c. The foundation was placed on gravel. It was reported that #5 dowels were placed along the north side and embedded 6" into native rock. Wall construction was reported to be 10" CMU with #5 @ 16" o.c. vertical and #5 horizontal @ 8" o.c. with matching comer bars. The roof was not constructed at the time of inspection however forms were on site. The Roof construction will consist of Coming Lite Deck 12 + forms system with 3000 psi concrete. The roof will bear on the masonry walls and will be tied to the walls with #5 dowels @ 16" o.c. Each tee beam stem shall be reinforced with (2) #4 bars and the 2 '/2" slab will be reinforced with #3 bars @ 15" o.c. These forms will span the 8'-8" and 14"-0" dimensions of the tank. Analysis The above information was used to analyze the tank for structural strength. The following design criteria and material specifications were used; Roof Snow Load — 40 psf Wind Load 90 mph Exposure B Concrete Strength F'c — 3000 psi Masonry Strength fm = 1500 psi Reinforcing Bars ASTM A615 Grade 60 Assumed Allowable Soil Bearing Pressure = 2000 psf Assumed Lateral Earth Pressure = 45 pcf Concrete design was verified for conformance with ACI 318 Building Code Requirements for Structural Concrete, and ACI 350 Code Requirements for Environmental Engineering Concrete Structures. Masonry Design was in accordance with ACI 530 Building Code Requirements and Specification for Masonry Structures. Flat plate analysis was used to verify the wall sections and base slab. Two design conditions were considered; Load Case I: Hydrostatic Test without soil backfill Load Case 11: Empty with soil backfill and roof snow load Results The proposed roof design is adequate for the design dead and snow loads. The masonry wall design is governed by the long wall on the east side. Due to the high ratio of length to height the wall behaves similarly to a cantilevered retaining wall. Considering a case where the roof is in place to help brace the wall, the calculated moments in the wall exceed the allowables per code. The other walls are satisfactory. The foundation is adequate with respect to the assumed allowable bearing pressures. Adequate frost depth of 36" has not been provided. If the soils are frost susceptible then there is a chance for differential heave to occur. The geotechnical engineer should be consulted to further evaluate the frost heave potential of the bearing soils. Additionally, the preliminary geotechnical report by HP Geotech and dated December 5, 2005 indicated the presence of expansive soils on the property. Minimum design bearing values were not provided but based on my experience with soils in the area this system would not likely attain the minimum pressures required to withstand the forces developed by expansive soils. Differential settlement / heave would be the result if expansive soils were to become wetted. The base slab is marginally acceptable for the design loads. Reinforcement; however, does not meet acceptable minimum recommendations for temperature and shrinkage control nor does it meet acceptable criteria for crack control of concrete water containment structures. Conclusions This investigation was limited to the structural integrity of the tank only. I have made no attempt to verify waterproofmg details, piping details, tank capacity or the suitability of this tank for use as a•water storage tank. Furthermore, I have not verified the details of construction through site inspection or photographs_ All structural systems were found to be satisfactory except for the east wall and the base slab. It is recommended that a counterfoil wall be constructed at approximately the mid point of the east wall. The wall can be made of 10" CMU with #5 vertical bars @ 16" o.c. Vertical bars can be drilled & epoxyed into the base slab with 5" embedment. The wall can terminate 8" or one CMU course below the roof and should have a minimum length of 5'-0". #5 horizontal bars should be provided @ 16" o.c. Drill & expoxy horizontal bars into the existing east wall with 5" embedment. Hydrotesting of the tank is recommended and the roof structure must be in place to brace the walls during the test. While the base slab should be adequate for the design loading, cracks may develop under design stresses. Cracks do not necessarily indicate structural failure but they are not desirable in water containment structures. It is recommended to investigate coatings and / or waterproofing systems that would be capable of spanning and sealing random cracks in the base slab. A similar system should be employed on the walls due to the large number of masonry joints. The design of such a waterproofing system is beyond the scope of this investigation. Additionally the concrete should be monitored for signs of cracking or spoiling in the area of the dowels embedded into rock. This detail can provide a pathway for moisture to corrode reinforcing bars and subsequently cause expansion of the concrete. Please do not hesitate to contact me @ 970-984-3949 for any questions regarding this letter or if 1 can be of further assistance. Res ctfully, Landon An erson, P.E. CALCULATION WORKSHEET Order No. 19116 (D1-91) PAGE OF CLIENT TV A lJ 774,(.1e< JOB NUMBER SUBJECT BASED ON DRAWING NUMBER BY CHECKED BY APPROVED BY DATE 0 it Q A -41 t v� CP64- O''rT .J &L -.- Z 3"+ ck,A v',/,AL-L6 / %F • CALCULATION WORKSHEET Order No. 19t16 {01-91) 54'7- .7.- PAGE vPAGE OF CLIENT AAS r/A4l '7 11,1k JOB NUMBER SUBJECT c v J TTA V✓ 44— BASED ON DRAWING NUMBER BY CHECKED BY APPROVED BY DATE g'7 c r iGii! ,4 r.1 5 A MAHAN SUBDIVISION OPINION OF PROBABLE COST for Security September 5, 2008 Q 9i 1? T oUo �?qqi=�c; 4�I _# 35964 ;r U<. trt �� ;�✓Yea- Description Quantity Units Price _ Cost Percent Complete Remaining Cost Grading and Earthwork _ Not Applicable 0 LS - $ - 100% $ - Subtotal = $ - $ - Potable Water Pressure Filter with 1 Micron Cartridge 1 EA 200.00 $ 200.00 0% $ 200.00 UV Light Disinfection System 1 EA 500.00 $ 500.00 0% $ 500.00 Pressure Guage 2 EA 50.00 $ 100.00 0% $ 100.00 10,000 Gallon Water Tank 1 EA 40,000.00 $ 40,000.00 90% $ 4,000.00 Subtotal = $ 40,800.00 $ 4,800.00 Sanitary Sewer Not Applicable 0 LS - $ - 100% $ Subtotal = $ - $ - Miscellaneous Construction Removal of "Framed Dugout" 1 LS 5,000.00 $ 5,000.00 100% $ - Removal of Fence Corner 1 LS 1,000.00 $ 1,000.00 100% $ - Trim Tree 1 LS 500.00 $ 500.00 100% $ - Removal of Fencing and Brush from CR 126 1 LS 2,000.00 $ 2,000.00 100% $ - Weed Management 1 LS 2,000.00 $ 2,000.00 0% $ 2,000.00 Subtotal = $ 8,500.00 $ 2,000.00 Subtotal = $ 49,300.00 $ 6,800.00 5% Contingency $ 2,465.00 0% $ 2,465.00 2 112% Construction Testing $ 1,232.50 0% $ 1,232.50 2 1/2% Bonding $ 1,232.50 0% $ 1,232.50 Total = 54,230.00 $ 11,730.00 Mountain Cross Engineering, Inc. has no control over the cost of labor, materials, equipment, services furnished by others, or market conditions therefore does not guarantee that proposals, bids, or actual construction cost will not vary from the above opinion of cost.