| Accident History | Chemicals | Emergency Response | Registration | Source | Executive Summary |

This document comprises the Risk Management Plan (RMP) for the City of Redlands (City) 
Water Treatment Plant located at 1604 N. Crafton Avenue in Redlands, California 92374 (also 
referred to within the City as the Horace Hinckley Water Treatment Plant). The City also operates one other stationary source subject to the federal RMP regulations. A separate RMP has 
been submitted for that Plant. 
The purpose of this document is to comply with the risk management planning requirements as 
set forth in Section 25535(d) of Article 2 of Chapter 6.95 of the California Health and Safety 
Code (also known as the California Accidental Release Prevention Program - CalARP) and Part 
68 of Title 40 of the Code of Federal Regulations (40CFR Part 68), also known as the federal 
Accidental Release Prevention Requirements: Risk Management Programs or the federal RMP. 
The scope of the RMP includes all operations conducted at the Plant which involve the storage, 
handling and/or use of chlorine. 
The Horace Hinckley Water Treatment Plant is a conventional water treatment plant which 
utilizes rapid mix, flocculation, sedimentation, filtration and disinfection. The Plant treats raw 
water from two sources: the Santa Ana River and the State Water Project. The untreated or raw 
water entering the plant contains sand, suspended particles, and microorganisms, collectively 
referred to as turbidity, that must be removed before the water enters the distribution system. The 
basic treatment processes include sand chamber, flocculation basins, sedimentation basins, and 
filters. Polymers and other chemicals are added at various points to condition the water. Chlorine 
is added for water disinfection. Chlorine is a regulated substance subject to the federal RMP 
The chlorine system is composed of four principal components: 
 The chlorine container and feed system (i.e., gas transfe 
r piping), which supplies the chlorine 
 The chlorinators and injectors, which meter the chlorine gas and mix it with feed water; 
 The chlorine solution transfer piping, which conveys the chlorine solution to the end use points 
and diffuses it into the plant flow, and 
 The chlorine residual analyzer, which measures and records chlorine concentrations. 
Chlorine Containers and Feed System 
The chlorine container and feed system is located in the chlorine storage room. Liquid chlorine is 
received in one ton containers via truck and stored in the chlorine storage room on trunnions. The 
trunnions are fabricated from steel and have cadmium plated steel rollers. A maximum of eight 
full one ton containers (i.e., a maximum inventory of 16,000 pounds of chlorine) may be present 
inside the chlorine storage room at any time. 
The two chlorine scales are sized to hold two standard one ton containers each (each chlorine 
container has a total weight of approximately 3700 pounds of which 20 
00 pounds is chlorine). 
Thus, two containers are manifolded together and set on a tandem scale. The scales have heavy 
duty bushed bearing trunnions to permit cylinder rotation. The container weight is displayed on 
an wall mounted 18-inch diameter dial. The containers are shuttled on and off of the scale and 
delivery truck by a container hoist system. 
From the containers, flexible connections lead to the chlorine header. From the chlorine header, a 
one-inch chlorine gas line leads to the chlorinators. Automatic switchover valves are provided on 
the discharge piping of the chlorine ton containers which automatically switches the "lead" container tandem with the "standby" container tandem when the lead container tandem supplies 
insufficient chlorine gas pressure. For each tandem, two lines are provided (one for each 
container) leading to two downstream chlorinators. The feed lines are piped in parallel to allow one chlorinator to operate on-line and the second unit as a standby. 
ators and Injectors 
Two floor standing chlorinators are located in the chlorinator room. The principal units included 
in each chlorinator are as follows: an indicating rotameter, a V-notch variable cross-section 
orifice for metering, a manual feed rate adjuster for the orifice, a vacuum differential regulating 
valve, and an automatic feed controller for the orifice. 
A vacuum is formed within each of the chlorinators by utility water passing through the injector. 
When the water moves through the injector a suction is created that opens the differential 
regulating valve and the vacuum relief valve. The entire unit is full of air at this point as the 
chlorine supply line has not yet been opened. When the chlorine feed line is opened, the vacuum 
relief valve closes replacing the air in the chlorinator with chlorine gas. 
Each of the two injectors consists of a venturi-type nozzle with vacuum gauge and a ball valve. 
Chlorine gas is drawn from the chlorinator through a one-inch PVC pipe in 
to the venturi, where 
it mixes with utility water. The water is supplied via a two-inch utility water line that is equipped 
with a plug valve and a ball check valve. The resulting chlorine solution is conveyed through 
separate lines to the chlorine solution distributor. Each injector can serve either of the two 
Chlorine Solution Piping 
Upon leaving the injectors, the two chlorine solution lines are manifolded in the solution 
distributor. Two rotameters are provided which allow the chlorine solution to be directed to the 
two main feed points (the flash mix basin and the clearwell). They are valved in such a way that 
each rotameter can serve the same injector, and therefore the same chlorinator, at the same time. 
Chlorine Residual Analyzer 
The two chlorine residual analyzers continually measure and record the residual chlorine content 
in the plant effluent (one measures the residual chlorine content of the clarified well and the other 
measures the residual chlorine cont 
ent in the clearwell). If a level of chlorine is detected below 
the desired level, a low chlorine residual alarm signal is sent to the main control panel. 
The RMP regulations require that at least two types of release scenarios be evaluated for their 
potential to impact off-site populations: 
 the worst case release; and 
 an alternative release (that is more credible) 
A number of hypothetical accidental release scenarios were postulated and evaluated for the 
RMP. These scenarios were categorized into worst-case release scenarios and alternative release 
scenarios. Each of these categories of hypothetical accidental release scenarios is discussed 
Worst-Case Release Scenario 
In this scenario, one of the one-ton containers of chlorine on site experiences a catastrophic 
failure due to an unknown external event. This scenario could be initiated by an external event 
(i.e., an airplane, missile or meteorite impacting the chlorine buil 
ding where the ton containers 
are located). It is highly improbable that this scenario would be initiated by a seismic event. 
However, the possibility of this scenario being initiated by a seismic event can not be completely 
discarded. This scenario is considered to be extremely unlikely. In the highly unlikely case that 
this scenario occurs, approximately 2,000-pounds of chlorine would be released. The release of 
chlorine could occur outdoors or indoors. Since the release can occur out-doors (i.e., outside of the chlorine storage building) the enclosure provided by the chlorine building was not taken into account in evaluating the off-site consequences. 
Rather, it was assumed that the chlorine released during the catastrophic accident was released 
outdoors forming a cloud of chlorine vapor. The resulting vapor cloud was assumed to freely 
migrate off-site. Utilizing the methodology specified by USEPA, the estimated vulnerable zone 
for this accidental release scenario is approximately 1 
Figure ES- 1 presents a graphical representation of the vulnerable zones for the worst-case 
release scenario for accidental releases involving chlorine. Table ES- I provides a listing of 
sensitive receptors located within the vulnerable zone. As shown, the only sensitive receptors 
located within the vulnerable zone are recreation areas. 
Alternative Release Scenarios 
Alternative release scenarios which are considered to be more likely to occur are those which 
may result in the release of anywhere from less than one-pound to up to 10-pounds of chlorine. 
These scenarios include situations such as delivery of a leaking one-ton container of chlorine to 
the Plant, a pinhole leak in the chlorine transfer piping and a partial or complete failure of the 
chlorine transfer lines (either 100-percent vapor or chlorine dilution water) at various points in 
the system (either in-doors or out-doors). In order to be conservative in the estimation of the 
vulnerable zone, it was assumed that  
10-pounds of chlorine was released during an accident 
involving the complete failure of a vapor transfer line from a one ton container. In such a 
situation, the loss of vacuum from the system would result in the automatic isolation of the one 
ton container at the container valve. However, in order to be conservative, it was assumed that 
the materia! was released directly outdoors (although the full length of the vapor transfer lines is 
located indoors. Thus, the system enclosure provided by the chlorine building was not taken into 
account in evaluating the off-site consequences. Utilizing this assumption is much more conservative in nature and resulted in the estimation of the largest vulnerable zone for these types 
of accident scenarios. The resulting cloud of chlorine vapor was assumed to freely migrate off-site. Utilizing the methodology specified by USEPA, the estimated vulnerable zone for these 
types of scenarios is approximately 0.1 miles. 
Figure ES-2 presents a graphical repres 
entation of the vulnerable zones for the alternative-case 
release scenario for accidental releases involving chlorine. Table ES-1 provides a listing of 
sensitive receptors located within the vulnerable zone. As shown, the only sensitive receptors 
located within the vulnerable zone are recreation areas. 
During the five years preceding the submittal of this RMP, the Treatment Plant has NOT had any 
releases of chlorine which have resulted in: 
 Onsite deaths, injuries, or significant property damage; or 
 Known offsite deaths, injuries, property damage, environmental damage, evacuations, or 
sheltering in place. 
The Accidental Release Prevention Program at the Treatment Plant consists of a series of 
programs, procedures and policies designed to minimize the risk of accidental releases involving 
chlorine. These programs include design and operating controls such as com 
pliance with 
specified codes, the health and safety program, numerous standard operating procedures, the 
equipment inspection and maintenance program (including a mechanical integrity and preventive 
maintenance program), the management of change program, pre-start-up review, fire protection 
and hot work permit program, management of- and safety of- contractors, accident/incident 
investigation procedures, emergency response plan, RMP compliance auditing program, record 
keeping and a variety of training programs. Details of each of these components of the Plant's 
Accidental Release Prevention Program are provided in the document entitled Risk Management 
Plan (RMP), Volume I - Prevention Program. 
There are several detection and monitoring devices and alarms placed at strategic locations 
throughout the Plant. Table ES-2 provides a summary listing of these devices as well as their 
sensitivities. In addition, there are portable fire extinguishers located throughout the Plant. 
The City recognizes that emergency planning and emergency response are an integral component 
of risk management. As such, the City currently has an emergency response plan and an 
emergency evacuation plan in place at the Treatment Plant as part of its hazardous materials 
business plan (HMBP). However, as a measure to improve safety, the City is currently 
developing a specific emergency response program for emergencies involving chlorine. 
A detailed hazard and operability study (i.e., hazards analysis) was performed on ALL operations 
involving chlorine in order to evaluate the potential for accidental releases. As a result of this 
hazards analysis a number of recommendations were made to improve the safety of the operations conducted. A summary of the recommended actions is provided in Table ES-3. Table 
ES-3 also presents the implementation status of the recommended actions. As shown, the City 
has already implemented a number of th 
e recommendations. Table ES-3 also presents the expected date of implementation for those recommendations not yet implemented. 
The City recognizes that some persons may be interested in obtaining more detailed information 
regarding risk management prevention program components not discussed herein. Interested 
parties that have additional questions regarding the City's Risk Management Plan, are directed to 
Mr. Stephen C. Dickey 
Water Superintendent 
City of Redlands 
Municipal Utilities Department, Water Division 
P.O. Box 3005 
Redlands, California 92373
Click to return to beginning