Full Text
New Development Water and Wastewater Design Guidelines June 2019 City of Kalispell 1 Version 2019.1 Water Distribution System Planning Values and Design Guidelines The water system information utilized to develop these design guidelines is from the City’s most recent Water Facility Plan Update (WFPU), City Standards, and Montana DEQ guidelines. Table 1 provides planning values to estimate water demands. The planning values are calculated from historical water consumption; it’s the design engineer’s responsibility to ensure the planning values are sensible for the development being constructed. Additionally, it’s recommended to check that the infrastructure being implemented aligns with the calibrated water system model. Table 2 provides water distribution system design guidelines including pressure, velocity, headloss, and fire flow requirements. Table 1. Water Demand Planning Values for Sizing Infrastructure1 Water Demand Planning Values Average Daily Demand (ADD) Land Use Type Recommended Planning Value Single Dwelling Residential 350 gpd Multiple Dwelling Residential 240 gpd/DU General Commercial 870 gpd/acre Neighborhood Office 330 gpd/acre Industrial 470 gpd/acre Light Industrial 160 gpd/acre Public Institutional 150 gpd/acre Peaking Factors to Calculate Maximum Daily Demand (MDD) and Peak Hourly Demand (PHD) Description Peaking Factor MDD Peaking Factor2 3.00 PHD Peaking Factor3 1.85 1 Abbreviations: gpd = gallons per day I DU = dwelling unit 2 Use to convert ADD to MDD. Multiply this peaking factor by the ADD to calculate MDD. 3 Use to convert MDD to PHD. Multiply this peaking factor by the MDD to calculate PHD. Table 2. Water Distribution System Design Guidelines1 Water Distribution System Design Guidelines Pressure Requirements Parameter Pressure (psi) Recommended Operating Pressure Range 50 – 80 Maximum Pressure 100 Minimum Pressure during Peak Hourly Demand 50 Minimum Pressure during Fire Flow 20 Velocity Requirements Parameter Velocity (fps) Transmission Pipelines (12-inch and larger) Less than 3 Distribution Pipelines (10-inch and smaller) Less than 5 ---PAGE BREAK--- New Development Water and Wastewater Design Guidelines June 2019 City of Kalispell 2 Version 2019.1 Table 2. Water Distribution System Design Guidelines (Continued)1 Water Distribution System Design Guidelines Headloss Requirements Parameter Headloss (feet per 1,000 feet) Transmission Pipelines (12-inch and larger) Less than 2 Distribution Pipelines (10-inch and smaller) Less than 5 Fire Flow Requirements2 Land Use Type Flow Rate (gpm) Duration (hours) Residential 1,500 3 Commercial 4,000 4 Industrial 4,000 4 1 Abbreviations: psi = pounds per square inch I fps = feet per second I gpm = gallons per minute 2 The City Fire Department follows the International Fire Code to determine needed fire flow. These are general requirements for planning purposes and may not be indicative of the requirements for specific developments or buildings. Wastewater Collection System Planning Values and Design Guidelines The wastewater system information utilized to develop these design guidelines is from the City’s most recent Wastewater Facility Plan Update (WWFPU), City Standards, and Montana DEQ guidelines. Table 3 provides planning values to estimate wastewater flows. The planning values are calculated from historical wastewater generated; it’s the design engineer’s responsibility to ensure the planning values are sensible for the development being constructed. Additionally, it’s recommended to check that the infrastructure being implemented aligns with the collection system model. Table 4 provides wastewater collection system design guidelines for both force mains and gravity mains. Table 3. Wastewater Flow Planning Values for Sizing Infrastructure1 Wastewater Flow Planning Values Average Daily Flow (ADF) Land Use Type Planning Value Single Dwelling Residential = 1 ERU 200 gpd = 1ERU Multiple Dwelling Residential = 0.8 ERU/DU 160 gpd/DU = 0.8 ERU General Commercial 540 gpd/acre Neighborhood Office 200 gpd/acre Industrial 260 gpd/acre Light Industrial 90 gpd/acre Public Institutional 60 gpd/acre Peaking Factors to Calculate Peak Hourly Flow (PHF) Description Peaking Factor PHF Peaking Factor (From Montana DEQ Design Standards)2 = 18 + 4 + = ℎ 1 Abbreviations: gpd = gallons per day I DU = dwelling unit 2 Fair, G.M. and Geyer, J.C. “Water Supply and Waste-water Disposal” 1st Ed. John Wiley & Sons, Inc. New York, (1954), P. 13 3 If I/I is anticipated, a planning value of 250 gpd per ERU shall be used ---PAGE BREAK--- New Development Water and Wastewater Design Guidelines June 2019 City of Kalispell 3 Version 2019.1 Table 4. Wastewater Collection System Design Guidelines Wastewater Collection System Design Guidelines FORCE MAINS General Design Guidelines Parameter Value Minimum Velocity 4 fps Maximum Velocity 8 fps Minimum Diameter 4-inch Design C-Factor (Hazen Williams)1 120 GRAVITY MAINS Minimum Slope Requirements Diameter Minimum Slope (feet / 100 feet) 8-inch 0.400 10-inch 0.280 12-inch 0.220 14-inch 0.170 15-inch 0.150 16-inch 0.140 18-inch 0.120 21-inch 0.100 24-inch 0.080 27-inch 0.067 30-inch 0.058 33-inch 0.052 36-inch 0.046 39-inch 0.041 42-inch 0.037 General Design Guidelines Parameter Value Minimum Velocity 2.5 fps Maximum Velocity 15 fps Minimum Diameter 8-inch Design Roughness Coefficient (Manning’s)2 0.011 Minimum Bury Depth (Top of Pipe) 4 feet 1 This design C-Factor is for new and/or smooth pipe (i.e. PVC). If utilizing a pipe with a rough interior, utilize a lower C-Factor (refer to textbook values). 2 This design roughness coefficient is for new and/or smooth pipe (i.e. PVC). If utilizing a pipe with a rough interior, utilize a higher roughness coefficient (refer to textbook values).