Example 1.3. A black weighing W = 10 kN is resting on an inclined plane as shown in Fig. 1.10(a). Determine its components normal to and parallel to the inclined plane.

Solution: The plane makes an angle of 20° to the horizontal. Hence the normal to the plane makes an angles of 70° to the horizontal i.e., 20° to the vertical [Ref. Fig. 1.10(b)]. If AB represents the given force W to some scale, AC represents its component normal to the plane and CB represents its component parallel to the plane. Thus from ∆ABC, Component normal to the plane = AC W cos 20° = 10 cos 20° = 9.4 kN as shown in Fig. 1.10(b) W sin 20° 10 sin 20° = 3.42 kN, down the plane Component parallel to the plane From the above example, the following points may be noted:

1. Imagine that the arrow drawn represents the given force to some scale.

2. Travel from the tail to head of arrow in the direction of the coordinates selected.

3. Then the direction of travel gives the direction of the component of vector.

4. From the triangle of vector, the magnitudes of components can be calculated.

Example 1.4. The resultant of two forces, one of which is double the other is 260 N. If the direction of the larger force is reversed and the other remain unaltered, the magnitude of the resultant reduces to 180 N. Determine the magnitude of the forces and the angle between the forces.

Solution: Let the magnitude of the smaller force be F. Hence the magnitude of the larger force is 2F. Thus F₁F and F₂ = 2F Let 9 be the angle between the two forces. From the condition 1, we get RF²+2FF₂ cos 0 + F22 = 260 F² + 2F (2F) cos + (2F)2 = 2602 5F2 + 4F2 cos 0 = 67600 i.e.. ...(i)

Program Components of Wastewater Collection Systems Management

Stakeholders may find useful several components of the system used by operators.

These items should be designed accordingly. Sensitive or secure information should also be taken into consideration as it relates to privacy, terrorism, and other misuse.

Program components that stakeholders may find useful are outlined below.

Service maps may include spatially related service area as constructed, topo-graphical information, street addresses, and customer information. This level of detail assists in planning, service availability requests, and in field responses to complaints.

Organizational charts of utility personnel by function define who is responsible for what activity and how to contact them.

Asset data may include size, material type, age, and depth and may be contained in a database or mapping system. Typical database formats include a computerized maintenance and management system (CMMS) for asset characteristics and history or a geographical information system (GIS) for spatial relationship representation. Information may be used in planning, system analysis, budgeting, service avail-ability reviews, and field responses to complaints.

Several types of data might be collected for a sewer pipe:

Size (diameter);

Length (miles, footage, and laying length);

Type (gravity, force main, collector, interceptor, lateral, trunk, siphon, or pipe bridge);

Material (vitrified clay pipe, concrete, polyvinyl chlorine, cast iron pipe, duc-tile iron pipe, or high density polyethylene);

Age (install date);

Depth (cover for excavation and overburden evaluation);

Location (right-of-way, easement, or private property);

Service connections (tee stations, depth, length, material size); and

Historic condition-logs, televising, maintenance and repair records (work orders).

Information that might be collected for manholes (manways) include:

Type (concentric, eccentric, chimney, tee, catch basin, regulator, vault);

Location (right-of-way, easement, or private property);

Size and depth;

Casting type and diameter;

Casting and invert elevations; and

Historic condition.

      Various pieces of data should be collected for pumping stations (for more guide-lines, refer to the Pumping Station Operations and Maintenance section):

Location (street address or other geo-coding for mapping);

Type (centrifugal, ejector, grinder, submersible);

Schematics (piping, electrical), which assists in understanding typical opera-tion and in modifications during emergency or maintenance activities;

Controls (what controls what);

Equipment (install and service dates, maintenance records, warranties);

Backup power (remote or onsite);

Valves (isolation, purge, and air relief);

Force main (size, material, length, terminus);

Metering (type, location, reading units); and

Historic condition.

Standard operating procedures (standardized format throughout agency) can be used as a training tool and reference by employees and other stakeholders. Work-process flowcharts (standardized format throughout agency) also can serve as a training tool and reference. Several other plans are valuable:

Operations and maintenance manuals-assists as a training and reference tool by employees and other stakeholders;

Master plans-multiyear outline of system expansion or modification that meets specific operational projections;

Policies-application guidelines of regulation or operational practices); assists as a educational tool for customers and as a training and reference tool for employees;

Special programs-regulatory or capital-driven projects with specific regula-tory or operational objectives should also be documents. Examples of special pro-grams may include:

Capacity, management, operation, maintenance (CMOM)-a U.S. Environ-mental Protection Agency (U.S. EPA) program that establishes the basis for separated sewer collection systems for better operation using measures and goals as they relate to total system performance and improvement.

Long term control plan (LTCP)-U.S. EPA program that establishes require-ment for communities with combined sewer systems; shows progress toward standards consistent with the Clean Water Act by demonstrating adherence to water quality and improvements as required and affordable.

Nine minimum controls-U.S. EPA program that establishes the basis for the control and management of a combined sewer system. Part of the LTCP.

Rehabilitation-various operational and capital activities that reestablish system integrity, performance and reliability.

Expansion-various capital activities that result in an expansion of service area. Typically part of a master plan or 201 facilities plan.

Performance History, agency, complaint and expectations of waste water management system 

Depending on the nature and cause of a collection system problem, an operator may determine that a location requires a more frequent return cycle for evaluation. Common causes of problems include grease, roots, debris, pipe failures, and over-flows. Defects that cause mainline failure are best remedied through permanent cor-rection, which might not always be immediately practical or possible. An example would be a sewer main through a central business district that requires heavy, semi-annual cleaning. This sewer main may be identified as not requiring capital outlay for repair or replacement because of its location. It may remain on a cleaning and inspection cycle until conditions change, although this approach may not be standard for the rest of the system. Operator and staff will be able to make more informed deci-sions as they become familiar with the performance of the collection system through data and performance measure reviews.

Agency Resources

Depending on system size and budget, operators have many considerations and options concerning resources to accomplish program goals, including staffing and equipment needs.

Program objectives need to be weighed against staffing ability. Some references may recommend staffing levels based on system size, but technology use may affect those numbers. Determining an initial return cycle of the system for preventive main-tenance and the ability to respond to emergencies can be based on collected data to determine if staffing levels are adequate. Although attrition is reducing the number of knowledgeable staff, contract services have become more readily available. Peri-odic review of contract service availability and cost can be good information for the operator to compile and to compare to in-house staffing costs.

Program objectives also need to be weighed against equipment availability and the return frequency of pipeline and facility review or cleaning. Costs per unit of work on a regional or units-per-man-hour basis for cleaning and televising are avail-able through industry organizations or third-party vendors and contractors.

Customer Expectations/Complaints

Public awareness is becoming more of a consideration as it relates to program objec-tives and deliverables because of the immediate availability of information. This means that the operator must use judgment on how information is communicated to the public to ensure that the definition and execution of the program protects the agency from potential liability.

An example of operator judgment would be noting and reporting a sewer manhole overflow in a remote portion of the collection system. If the overflow extends outside of the easement or affects a receiving stream, then public notice would be appropriate. If it is contained in the immediate area, does not affect open land or receiving streams, and does not interrupt service to customers, then notification to the regulatory agency and corrective action may be enough. Information for events such as these could be posted on Web sites or on required regulatory reports with details shared upon request of customers, rather than unnecessarily alarming the public.

As indicated in other areas of this document, stakeholders can include system users, land developers, regulatory agents, and concerned citizens. Their perspective and interests can affect an operator's program. Basic information of interest to most customer types includes capacity of the collection system, appropriate use of the system, and the customer's responsibility in helping to maintain it.

As development occurs, an operator must make decisions about whether an existing system can accept the flow from a new connection or if an extension of the system is possible. The answers to these issues depend on the capacity of the system and availability of financing for improvements needed to serve development. New service agreements are recommended to be executed in writing and made publicly available to eliminate the potential for misunderstandings. Further discussion of capacity assurance planning is provided in Chapter 4 of this manual; system financing options are discussed in Chapter 8.

It is recommended that there be stated conditions concerning use of the collec-tion system. This is typically accomplished through a sewer use ordinance adopted by the local governing body. These documents typically correlate with other local code involving permitting, construction, inspection, and wastewater acceptance requirements. Specific conditions can include industrial or environmental compli-ance concerning pretreatment, which ultimately will require periodic testing and enforcement for noncompliance. Conditions also may include methods of connection and allowable discharges. For instance, roof drains and sump pumps would not be acceptable in a separated sewer system but may be in a combined sewer system. Also yard waste, dirt, rocks, construction waste, rags, personal hygiene products, and household grease are examples of items that should not be disposed of in a sewer col-lection system because of risk of line stoppages and overflows. Information such as this should be communicated to proactively educate the customer.

Just as the system operator has responsibility for maintaining and operating a collection system, so too should the customer have responsibility in its use and main-tenance. In addition to safe disposal, the customer also should be responsible for the condition of their service line, eliminating the potential for root intrusion and capacity-depleting groundwater infiltration. The system operator should make this clear in local code, upon connection for service to the system, and through various agency communications. Sometimes, financial hardship may affect a customer's ability to make required corrections to their service line. The utility will need to deter-mine how to address this and whether system expenditures on private portions of the collection system will yield a return worth pursuing. Many locations have deter-mined that addressing private laterals and eliminating unapproved connections (roof drains, sump pumps, etc.) has contributed to removal of extraneous flow and its related non-revenue effect to the system. Some systems have established loan or grant programs for qualifying customers.

Community Interests

The development of any area is important to economic growth and quality of life. Operators must coordinate with development interests in use of existing or con-struction of new infrastructure. Receiving sewers, pumping stations, and treatment facilities must be considered when enabling new connections. Type of use and dis-charge are other factors to consider. A master sewer plan based on existing and potential land use is a good tool to facilitate discussion about development and the interests of the community. Typical master plans project future conditions for 25 years or more and should be reviewed and updated periodically. Master planning and capital improvement planning is discussed in Chapter 4 of this manual.

Regulatory Resources

Interpretation of regulations by local agencies is critical to funding, staffing, equip-ment, and overall program objectives. Regulatory agencies can serve as a great resource for information and as an advocate with other stakeholders. As with any relationship, trust is earned through communication and demonstration of responsi-bility and accountability. A collection system operator may achieve this trust through timely, credible, and dependable reporting. Operators can further develop relation-ships by working on industry activities that enable cross-agency interaction and through good system management to ensure few incidences or failures occur.

ESTABLISHING OR EVALUATING AN OPERATIONS AND MAINTENANCE PROGRAM OF WASTE WATER MANAGEMENT

Although there are some basic regulatory guidelines for system performance, establishing, organizing, and reevaluating a program may save the operator time and money. Data should be collected for several parameters that affect O & M: system asset characteristics, asset maintenance and operational history, asset manufacturers' recommendations, utility resources, customer expectations/complaints, community interests, long-term planning, and regulatory specifics. Each system may have unique parameters to consider. A practical approach that helps a system meet regulatory and customer expectation is recommended.

Following are examples of how data collection and data use affects an O & M program.

System Asset Characteristics

System asset characteristics include physical attributes such as size, age, material type, sewer type, location, depth, access, slope, flows, and content.

For example,

Trunkline A:

A 450-mm (18-in.) diameter gravity sewer main,

10 years old,

-Constructed of polyvinyl chlorine pipe,

- Sanitary sewer,

Inside a right-of-way,

With better than minimum slope,

Few physical connections, and

- Quarter to half-pipe diurnals.

Trunkline B:

- Approximately 450-mm (18-in.) diameter gravity sewer,

70 years old,

Constructed of concrete,

Combined sewer,

In easement along creek bank,

Minimum or below-minimum slope,

Diurnals ranging from zero flow to half-pipe, and

Multiple commercial connections including restaurants (grease).

       In this example, an operator may consider inspecting and cleaning trunkline B on a more frequent return cycle than trunkline A. Primary reasons for this approach would be type of material; joint condition; limited access during wet weather; typical low-flow conditions and slope, which creates the potential for debris collection; and grease buildup because of the restaurants (see the discussion on fats, roots, oils, and grease programs later in this chapter). Over time, field maintenance crew experience, observation of sewer system use, maintenance and corrective action records, or increases in flow may result in a different return cycle than originally determined. Further discussion of information management and using data to support better O & M decisions is provided in next of this manual.