design manual for water and sewer facilities

8/13/2019 Design Manual for Water and Sewer Facilities

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Adopted July 20, 2006 2 - 37

2.2.7. Fire Protection

2.2.7.1. General: When fire protection is to be provided, water maindesign shall be such that fire flows and facilities are in accordance withrequirements of the State Fire Marshall and of the State InsuranceServices Office.

2.2.7.2. Sizing Booster Pumps, Water Mains, Etc.: The designhydraulic flowrate for fire hydrants shall be as provided in the Division ofUtilities and Solid Waste management Rules and Regulations. Afterconstruction, hydrants will be color coded according to their requiredflowrate capacity by the DUSWM Department of Operations andMaintenance.

2.2.7.3. Sprinkler Systems: For single and multiple family dwellings,townhouses, and commercial projects that require sprinkler systems,the engineer should consult with the Division of Utilities and Solid WasteManagement, Department of Engineering and Planning.

2.2.7.3.1. Adequate water at the meter outlet during sprinklerdemand and major water appliance demand combinedflowrates. Larger service connection piping and meter may berequired, especially when water pressure is less than 45 psi.

2.2.7.3.2. Adequate backflow prevention to keep stagnantsprinkler water (also etylene glycol) from flowing back into theCounty's system.

2.2.7.3.3. Enlarged private property piping to maintainpressure to sprinklers under high flowrate conditions.

Complete information and meter details, i.e., meter size, pipesize, vault size, etc. shall be shown on the plans.

2.2.8. Dead Ends

2.2.8.1. Requirements: In order to provide increased reliability ofservice, reduce head loss, and avoid taste complaints, occurrences ofdead ends shall be minimized by looping mains or providing tie-inswhere appropriate.

2.2.8.2. Fire Hydrants: No more than one fire hydrant is permitted onan unlooped 6-inch main.

2.2.8.3. Maximum Number of Dwellings: No more than 25 single familyor townhomes may be serviced on a dead end or cul-de-sac regardlessof the street configuration.

2.2.8.4. Private: Commercial and industrial developments that haveprivately owned and maintained water mains shall provide on-sitelooping for fire protection and overall system reliability, where necessary.


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Adopted July 20, 2006 2 - 42

it becomes buried by subsequent construction or site grading.If driveway locations are known, avoid placing meter vaultsand piping in or under the paved portion.

2.2.11.1.4. Double WSCs (DWSC) (that is when two metersare supplied to one connection pipe) may be permissible in

certain existing single family residential developments asapproved by DUSWM, Department of Engineering andPlanning. In locating meters at property corners, make everyeffort to avoid conflicts between the meter vault and drivewayareas. Double service connections are only permitted withthe 5/8-inch meter and standard vault. Double serviceconnections cannot be used when a pressure reduction valveor sprinkler service is involved.

2.2.11.1.5. Connection Crossing Property Boundary: Whena particular private property site has no access to a Countywater main except by routing water piping through a second

private property site, it is incumbent upon the ownerrequesting the water service to obtain a perpetual 10-footwide easement on said second site. The easement mustabut the existing right-of-way or easement containing thewater main and extend to the property receiving the waterservice. The WSC can be established with the meter locatedabout 1 foot inside the said second site. Such installationsare to be avoided unless compelling reasons are presented tothe Division of Utilities and Solid Waste Management forapproval. Approval of all interested County agencies is alsorequired, especially Planning and Zoning.

2.2.11.2. Sizing

2.2.11.2.1. In most cases, the size of the connection piping isdetermined by the size of the meter selected. When thesituation involves combinations of long runs of connectionpiping, sprinkler demands, commercial demands or lowpressure gradient in the main, the piping shall be over size.

2.2.11.2.2. Large Connections: Service connections 3inches and larger must be designed showing detail of serviceconnection piping, vault, and vault bypass piping in both planand profile.

2.2.11.3. Meters

2.1.11.3.1 General: See Section 2550 of the StandardSpecificationsand pertinent Standard Detailsfor residentialservices. Commercial and industrial


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design manual for water and sewer facilities

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