Chapter 4: Regulatory Requirements & Design Criteria

Transcription

1 Chapter 4: This chapter summarizes the City s regulatory requirements and minimum design criteria as established by the Washington Administration Code (WAC) Chapter for Group A Public Water Supplies. The City s Municipal Code details the administrative code for the city regulation applications and contracts for water service, water uses, connections, and disconnections of water service. The minimum design and performance standards for any new development or construction project in the City of Ocean Shores are based on the Washington State Department of Transportation s Standard Specifications for Roads, Bridges, and Municipal Construction 2012, the Group A Public Water Systems Manual (WAC ), and the Water System Design Manual (DOH# , December 2009 or latest edition) produced by the Washington Department of Health (DOH). Minimum design criteria addressed include water supply requirements, storage volume, distribution system and transmission main capacity, pumping capacity, back-up power systems, and water quality standards. These criteria are used to determine deficiencies in the existing water system and establish design requirements for any future improvements to the water system based on projected growth, and increase in demands within the City s service area. 4.1 REGULATORY REQUIREMENTS Federal, state, and county requirements are included in this regulatory requirement section Federal Requirements The City s public water system is regulated by the federal Environmental Protection Agency (EPA) under the Safe Water Drinking Act. EPA writes rules and regulations that dictate minimum standards related to water quality that all public water systems in the United States are required to meet. One requirement is for public water systems to report on the status of meeting the Maximum Contaminant Levels established for drinking water to the purveyor s customers. Ocean Shores is in compliance with all requirements established under the Safe Drinking Water Act and other federal regulations related to the operation of a public water system State Requirements The main purpose of the Office of Drinking Water, a part of the Environmental Health Division of the State of Washington DOH, is to protect the health of the people of Washington by assuring safe and reliable drinking water. This is performed through the creation and Page 4-1

2 Chapter 4 City of Ocean Shores enforcement of State regulations that meet or exceed the requirements established by the EPA. The Washington State Department of Health s Water System Design Manual is the primary document governing the sizing and design of Group A public water systems in the state. Washington Administrative Code (WAC) provides requirements for public water systems in the state, and WAC dictates what is required to be included as part of this. In 2007 the state adopted the Municipal Water Law, which provides for additional coordination, water rights assessment, and water use efficiency guidelines with which water systems must comply. This Plan sets forth the minimum design guidelines and planning requirements for the supply, storage, distribution, and quality of potable water within Group A public water systems County Requirements The County Environmental Health Division provides a variety of environmental and public health services for the citizens of Grays Harbor County. The Environmental Health Division helps to minimize exposure to health threats for its citizens. The County Planning and Building Department issues permits for Individual Water Systems and Public Water Systems. Ocean Shores is required to include information in its that is consistent with Grays Harbor County policies and comprehensive planning data. 4.2 RELIABILITY STANDARD In accordance with WAC , All public water systems shall provide an adequate quantity and quality of water in a reliable manner at all times. Reliability, in this case, refers to expectations consumers have in obtaining sufficient water at an acceptable pressure. From a health and safety perspective, low pressure creates chances for backflow or seepage that could allow contaminants to enter drinking water. High pressure could lead to excessive leakage or failure of water system facilities The City understands the need for reliability and strives to maintain adequate quantity and quality of water to their customers. Chapter of the City s Municipal Code provides detailed commitments, which the City has made to customers for maintaining reliable service. A copy of Chapter is found in Appendix B. As required by DOH, the water system must insure reliability which includes sufficient source and storage capacity, pumping capacity, hydraulic capacity, and emergency power generation for pumping as applicable to the water system. Page 4-2

3 City of Ocean Shores Chapter FIRE FLOW REQUIREMENTS As stated in WAC , if fire flow is provided, the distribution system shall also provide MDD plus the required fire flow at a pressure of at least 20 psi at all points throughout the distribution system and under the condition where the designed volume of fire flow reserve and equalizing storage has been depleted. Ocean Shores uses the requirement described under WAC , for the minimum fire flow as shown in Table 4-1 below: TABLE 4-1: MINIMUM FIRE FLOWS* Development Classification Type Flow Requirement (GPM/Minutes) Rural Residential Commercial and multifamily structures (greater than 4000 sq. ft.) None 500 gpm for 30 minutes 750 gpm for 60 minutes** Industrial Notes: 1000 gpm for 60 minutes** * Minimum flows are in addition to requirements for normal domestic maximum use. ** Commercial and industrial buildings may be subject to higher flow requirements when evaluated on an individual basis by the local fire protection authority. Minimum standards in most cases require less flow than categories in the guidelines published by the Insurance Services Office (Municipal Survey Service, 160 Water Street, New York, New York 10038) and therefore may not result in lower insurance rates. [Statutory Authority: RCW (Order 121), recodified as , filed 12/27/90, effective 1/31/91. Statutory Authority: Chapter RCW (Order 2840), , filed 7/31/89, effective 8/31/89. Statutory Authority: RCW (Order 1378), , filed 3/12/79.] 4.4 SOURCE REQUIREMENTS Ocean Shores uses the following source requirements: Source capacity must meet the maximum day demand of the water system. It is also recommended that the source is sufficient to meet the maximum day criteria while concurrently replenishing the fire flow reserve storage volume within 72 hours of its depletion. Water source pump stations should be capable of providing the maximum day demand for the system with 24 hours of pumping. Pump stations shall be provided with adequate net positive suction head (NSPH) at the inlet side of the pumps under peak hour demand or fire flow plus maximum day demand rate conditions. NSPH is a characteristic of the pumping equipment and configuration of the pipes and valves on the suction side of the pump. Page 4-3

4 Chapter 4 City of Ocean Shores Pump stations shall have an automatic shut-off in place for when the minimum storage tank level drops below 10 psi. Pump stations shall have power connections available to independent primary public power sources or provision for in-place auxiliary power if the pumps provide fire flow or are pumping from ground level storage. Generator fuel storage shall be sized to provide for two days of uninterrupted run-time at ADD flows, or two times the fire flow duration requirement, depending on the application Water Quality Standards In accordance with WAC , the City is responsible for fulfilling the standards of water quality. Under WAC , if the water supply exceeds its maximum contaminant level (MCLA) or its maximum residual disinfectant level (MRDL), the City takes follow-up action. The primary drinking water standards for contaminants are listed in Table 4-2. Page 4-4

5 City of Ocean Shores Chapter 4 TABLE 4-2: PRIMARY DRINKING WATER STANDARDS FOR CONTAMINANTS Source: WAC Inorganic Chemicals Primary MCLs (Mg/L) Inorganic Chemicals Secondary MCL (mg/l) Antimony (Sb) Chloride (Cl) Arsenic (As) 0.010* Fluoride (F) 2.0 Asbestos 7 million fibers/liter Iron (Fe) 0.3 Barium (Ba) 2.0 Manganese (Mn) 0.05 Beryllium (Be) Silver (Ag) 0.1 Cadmium (Cd) Sulfate (SO4) Chromium (Cr) 0.1 Zinc (Zn) 5.0 Copper (Cu) ** Physical Characteristics Secondary MCLs Cyanide (HCN) 0.2 Color 15 Color Units Fluoride (F) 4.0 Hardness None Established Lead (Pb) ** Specific Conductivity 700 umhos/cm Mercury (Hg) Total Dissolved Solids (TDS) 500 mg/l Nickel (Ni) 0.1 Disinfection Byproduct MCL (mg/l) Nitrate (as N) 0.1 Nitrite (as N) 10.0 Total Trihalomethanes (TTHMs) Haloacetic acids (five) (HAA5) Selenium (Se) 0.05 Bromate Sodium (Na) ** Chlorite 1.0 Thallium (Ti) Disinfectant Residual MRDL (mg/l) Notes: Chlorine Chloramines Chlorine Dioxide 4.0 (asc12) 4.0 (asc12) 0.8 (as C1O2) * Does not apply to TNC systems. ** Although the state board of health has not established MCLs for copper, lead, and sodium, there is sufficient public health significance connected with copper, lead, and sodium levels to require inclusion in inorganic chemical and physical source monitoring. For lead and copper, the EPA has established distribution system related levels at which a system is required to consider corrosion control. These levels, called action levels, are mg/l for lead and 1.3 mg/l for copper and are applied to the highest concentration in 10 percent of all samples collected from the distribution system. The EPA has also established a recommended level of twenty mg/l for sodium as a level of concern for those consumers that may be restricted for daily sodium intake in their diets. Page 4-5

6 Chapter 4 City of Ocean Shores 4.5 WATER SYSTEM DEMANDS Per the Water System Design Manual (December 2009), demands on a water system and its components must be estimated based on the amount of water its consumers will be using. Existing meter readings can be used to establish the estimates, incorporating measures for unaccounted-for water (leaks, flushing, WTP backwash, etc.). The design data will be used to estimate average day demand (ADD), maximum day demand (MDD), and peak hourly demand (PHD). These demands will be discussed below: Average Day Demand (ADD) In accordance with WAC , the ADD must be established using actual metered water source data. For Ocean Shores this equates to the WTP outlet volumes pumped into the distribution system. This data should be sufficient to account for seasonal or other cyclic changes in water demand. The data must show daily population using the water over the time the records are collected and reflect the uses associated with maximum occupancy for the developments. ADD has been calculated for the City and is discussed in Chapter 5 of this Plan Maximum Day Demand (MDD) The design for water system source, treatment, and equalizing storage together must meet the MDD. Metered records are also used for calculating the MDD for the water system. The MDD has been calculated for the City and is discussed in Chapter Peak Hourly Demand (PHD) To size equalizing storage, transmission lines, distribution mains, and some pumping facilities, PHD estimates shall be used. In accordance with the Water System Manual (December 2009), the water system must provide PHD while maintaining a minimum pressure 30 pounds per square inch (psi) throughout the distribution system. The City is able to estimate PHD since they have a meter on their primary distribution storage facility (3.0 MG Tank) that records water use in hourly increments. More information on PHD is provided in Chapter GENERAL WATER MAIN REQUIREMENTS General water main requirements will include pipeline velocities, water main extensions, water system design parameters, and water main locations. Page 4-6

7 City of Ocean Shores Chapter Pipeline Velocities Maximum velocity in distribution pipelines shall not exceed 2.5 feet per second (fps) under maximum day demand conditions. Flow velocities during fire events, for short segments, may exceed this maximum limit, but shall remain below 10 fps Water Main Pipeline Sizing Per WAC , minimum pipe diameter for all distributions and mains providing fire flow is 6-inches nominal inside diameter, except for looping and dead-end mains. The City s current standards require 8-inch minimum diameter for new system extensions, to which fire hydrants are connected. In order to reduce water age and stagnation during periods of low water use, 6-inch and 4-inch diameter mains are installed in locations where domestic flows can be maintained at sufficient pressure, and fire flows are not negatively impacted (i.e., 6-inch mains for distribution looping with no fire hydrant connections, and 4-inch mains for short dead-end pipes serving less than 10 homes). Distribution system capacity provides for PHD or MDD plus fire flow at a pressure of at least 20 psi and under the condition that the designed volume of fire flow reserve and equalizing storage has been depleted Water Main Pipe Specification New water mains will be constructed of cement mortar-lined, ductile iron pipe conforming to AWWA C151 and C104, minimum thickness Class 52 conforming to ANSI/APWA C110 or C153, with 250 psi minimum working pressure or polyvinyl chloride (PVC) conforming to AWWA C900 Class 150 (DR 18). When a new water main crosses a roadway, ductile iron pipe will need to be used. Polyvinyl chloride C900 pipe can be used in the rest of the system. 4.7 VALVES Valves will be resilient seat gate valves, with ductile iron bodies in accordance with AWWA C515, and shall be installed in a configuration that permits isolation of lines. In accordance with the Water System Design Manual (December 2009), valving should be sufficient to minimize the number of customers out of service when the City turns the water off for maintenance, repair, replacement, or additions. Additionally, on distribution mains with a diameter of 12 inches or less, it should be possible to isolate a length of water main no more than 1,000 feet by closing valves. Page 4-7

8 Chapter 4 City of Ocean Shores Combination Air/Vacuum Release Valves Air entrainment, air release, or combined air-vacuum relief valves are to be installed at appropriate high points in the system Flushing Valves, Blow-offs, and Hydrants A blow-off assembly or fire hydrant will be installed on all dead-end runs and at designated points of low elevation to provide a means for adequate flushing of the system. For scouring purposes, the blow-off assembly will be sized to achieve a minimum flow velocity of 2.5 fps in the main. 4.8 FIRE HYDRANTS According to the Water System Design Manual (December 2009) (WAC (3)), All fire hydrants shall conform to American Water Works Association specifications for dry barrel fire hydrants. Each hydrant shall have at least two hose connections of 2½-inch diameter each and one pumper connection with the appropriate connection size and style of thread or other connector as approved by the Fire Department. WAC also states Fire hydrants shall be located at roadway intersections wherever possible and the distance between them shall be no further than 600 feet. 4.9 CROSS-CONNECTION CONTROL Where the possibility of contamination of potable water exists, water services are equipped with appropriate cross-connection control assembles in accordance with DOH requirements. There are no cross-connections whatsoever between the City water distribution system and unapproved pipes, wells, pumps, private hydrants, tanks of non-potable fluid, or any other contaminating materials that may backflow into the water system Backflow Prevention The degree of public health protection required must be equal with the degree of hazard presented. In situations of known or potential physical or toxic health hazards, air gap separation and/or reduced pressure backflow preventers shall be required. Double check valve assemblies or pressure vacuum breakers are generally utilized where aesthetic or detrimental effects on water quality may occur. Each water system connection has unique problems arising from location, climatic conditions, service demands, and other factors. Consequently, each cross-connection is examined on an individual basis and the City makes the final determinations as to the degree of backflow protection required. Page 4-8

9 City of Ocean Shores Chapter 4 Backflow protection assemblies proposed for use can be found on the current list of approved assemblies by the DOH. All backflow assemblies are required to be tested annually by a Washington State certified backflow assembly tester. Copies of inspection reports are provided to the City Premise Isolation Where the City determines protection of the public water distribution system is necessary, a backflow preventer is installed at the property line equal to the degree of hazard as defined in WAC Installation of air gaps shall be approved by submitted drawings in accordance with the latest edition of the Cross-Connection Control Manual, Pacific Northwest Section AWWA. Double-check valve assemblies and reduced-pressure backflow assemblies are in accordance with the City s requirements Irrigation Systems Cross-connection protection is required for all irrigation systems. In general, pressure vacuum breaker assemblies may be acceptable for some irrigation system applications. Pressure vacuum breakers are required to be freeze-protected. In areas of flooding or where injection systems are used, double-check valve assemblies or reduced-pressure backflow assemblies are required STORAGE REQUIREMENTS Storage requirements are based on five components: operation storage, equalizing storage, standby storage, fire flow reserve storage, and dead storage. The minimum amount of storage required by DOH is to be equal to the equalizing storage plus the larger of the standby storage and fire flow reserve storage requirements (this is referred to as nesting by DOH). The recommended storage volume is larger than the minimum DOH requirement and equal to the sum of the equalizing, standby, and fire flow reserve storage components. The various storage components of total required storage are shown in Figure 4-1. Page 4-9

10 Chapter 4 City of Ocean Shores Figure 4-1: Storage Facility Schematic Operational Storage The operational storage is the volume of water available to supply the system under normal operating conditions while the source is considered off. Operational storage is determined and controlled by the water system operator through pump start/stop settings in the SCADA control system. The volume is set to preserve the necessary standby and fires storage in the tanks, while preventing excessive cycling of the source pumps Equalizing Storage Equalizing storage is the volume of water required to supplement source pumping capacity when system demands exceed the source pumping capabilities. The volume of equalizing storage must be sufficient to meet hourly water system demands in excess of the rate of supply and must be at an elevation sufficient to meet these demands at a minimum delivery pressure of 30 psi. The amount of required equalizing storage is to be calculated in accordance with the DOH Water System Design Manual. Page 4-10

11 City of Ocean Shores Chapter Standby Storage Standby storage is required in order to provide the available supply of water during supply source outages. Source outage may be caused by a pumping equipment failure, supply line failure, maintenance or repair, water quality contamination or other conditions that may cause interruption in supply. For single-source systems, standby storage requirements are twice the average day demand for a system, deliverable at 20 psi. For a multiple-source system, the standby storage is calculated as twice the average day demand, less the flow available with the largest source out of service, multiplied by the amount of time the remaining sources will be pumped each day. Although Ocean Shores has multiple wells, the source of supply is considered a single source since all wells are directed through the water treatment plant Fire Flow Reserve Storage Fire flow reserve storage must be equal to the amount of water required to accommodate fire demand under a specified duration of time. Fire flow requirements are determined by the City Fire Marshal. The minimum fire flow requirements are detailed in Section Dead Storage Dead storage is the amount of water not available at the minimum design pressure. Dead storage is not considered when determining volumes to provide operational, equalizing, standby, or fire reserve storage. All of the reservoirs in the City s system have booster pumps into the system, allowing effective use of nearly all of the storage. Therefore, dead storage in the city s system is minimal TELEMETRY SYSTEMS Telemetry systems must be compatible with the City s existing SCADA system. The system provides discrete status, continuous reporting, and control capability, which is both sending and receiving. It must also have an integral backup power supply able to sustain communication for a 24-hour period. Any expansions or modification to the City s SCADA system are reviewed and approved by the City s designated control system integrator BACKUP POWER REQUIREMENTS Backup power is provided at all sources or pumping stations which are required to be operational during power failures in order to meet system reliability requirements or to continuously maintain a positive distribution system pressure. Typically, emergency generators should have sufficient fuel onsite to run for 48 hours at ADD, or two times the fire flow duration at full flow. Page 4-11

12 Chapter 4 City of Ocean Shores 4.13 PROJECT REVIEW PROCEDURES Per the requirements of the City s Municipal Code Chapter , applications for line extensions are reviewed first by the water superintendent who determines whether the proposed line extension meets city construction standards and does not impair the city s ability to provide full water service. Secondly, the application is reviewed by the City s SEPA responsible official who complies with the City s SEPA Guidelines. Each application will then be forwarded to the city manager who will prepare a recommendation to the council. The council will then consider the Mayor s recommendations, make the necessary environmental decisions and either order the issuance of the applicant s line extension permit or reject the application. The issuance of a line extension permit may be made contingent upon any reasonable conditions. Before the start of construction, plans and specifications are reviewed and approved by the City. The applicant is responsible for paying all costs for the line extension including inspection by the City UTILITY CONNECTION PERMITS In accordance with the City s Municipal Code Chapter 13.06, Any individual, firm, corporation, or organization desiring to purchase water from the city shall make application therefor, upon a printed application form to be furnished for the purpose entitled Application to and contract with City of Ocean Shores, Washington, signed by the applicant and filed in the City office. Page 4-12