how$to$estimate$the$cost ?· how$to$estimate$the$cost$of$a$water ... (construction !specifications...

Download How$to$Estimate$the$Cost ?· How$to$Estimate$the$Cost$of$a$Water ... (Construction !Specifications ...…

Post on 12-Aug-2018

213 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • 4

    How to Estimate the Cost of a Water Main Installation in a City Street CPE Candidate No. 0114217 June 15, 2014

  • 5

    How to Estimate the Cost of a Water Main Installation In an Urban Environment Table of Contents Section 1 Introduction Page 6 Section 2 Types of Methods of Measurements Pages 6-11 Section 3 Project Specific Factors to Consider Affecting Takeoff and Pricing Pages 12-15 Section 4 Overview of Labor, Material, Equipment, Indirect Costs and Pages 15-18

    Approach to Mark-ups Section 5 Special Risk Considerations Page 18 Section 6 Ratios and Analysis Tools Used to Test the Final Bid Page 19 Section 7 Miscellaneous Pertinent Information Pages 19-21 Section 8 Sample Plan and Profile View Pages 21-22 Section 9 Sample Trench and Restoration Detail Page 22 Section 10 Sample Estimate- Takeoff and Pricing Sheets Pages 23-25 Section 11 Terminologies Glossary Page 26 Section 12 References & Copyright Releases Page 27

  • 6

    Section 1 Introduction

    This technical paper is focused on providing the reader with a general understanding of the

    necessary steps and procedures to complete a construction cost estimate for the installation of an

    underground water main in an existing city street. Unlike residential or commercial projects

    conducted in previously undisturbed virgin soil, water main installations in existing urban

    environments can present a great potential for difficult obstacles such as unforeseen utility conflicts,

    abandoned utilities, contaminated or hazardous soils, existing asphalt and roadway improvement

    restoration, traffic control, etc., which will require the cost estimator to consider much more than the

    labor, equipment and materials for the project.

    The basis for this technical paper is: Main CSI (Construction Specifications Institute 2004 Master Format) Division Division 33 Utilities Main CSI (Construction Specifications Institute 2004 Master Format) Subdivisions Subdivision 33 10 00 Water Utilities Subdivision 33 11 13 Public Water Distribution Piping Subdivision 33 12 13 Water Service Connections Subdivision 33 12 00 Water Distribution Equipment Section 2 Types and Methods of Measurements After the Estimator has conducted a thorough review of the contract documents and determined that

    the project falls within the guidelines of company policy to proceed with the estimate, he/she will

    need to conduct a quantity survey. The quantity survey or takeoff is one of the most important steps

    that the estimator will take in the process of developing the cost estimate. If the estimator is not

    careful in taking off the project quantities, it could lead to a costly error, which could detrimentally

    affect the price of the bid and result in a significant financial loss on the project. Before starting the

    quantity takeoff, the estimator will want to become very familiar with the trench section details and

    pipeline profiles for the watermain. The trench section details will provide the minimum depth and

    required cover of the watermain, minimum trench width, bedding, backfill material requirements

  • 7

    and asphalt thickness and restoration limits. If available, the pipeline profile should show the

    pipeline design depth and vertical alignment of the waterline from start to finish.

    A contract for a new watermain is typically bid by the unit price. The contract bid package will

    typically include a bid form that will include the engineers quantities for the various bid items. The

    contract bid form will list such items as Mobilization Lump Sum, Traffic Control-Lump Sum, Water

    Main-Lineal Foot, Tee-Each, Gate Valve-Each, Signal Detector Loop-Each, Asphalt Restoration-Square

    Foot, etc. with estimated quantities. The estimator will use this bid form to submit the estimated

    prices to the project owner.

    The bid form will also serve as a helpful guide in preparing the estimate. However, the estimator

    must be careful to always confirm the quantities and not assume that the contract bid item quantities

    provided by the engineer or owner are correct. If one of the bid items is presented as a final pay

    quantity, there will be no chance to receive additional compensation for actual quantities that

    exceeded the engineers bid estimate. Further, there are many appurtenances that will need to be

    included with the installation of the watermain, which may not be included on the bid form. The

    design engineer may have omitted a blow off assembly or air relief valve that will need to be included

    per the contract description of bid item or written specification. Vertical pipe offsets under existing

    utilities may not be included in the engineers estimate and should be considered. A cathodic

    protection system may need to be installed with anode bags and test stations. When these types of

    issues are discovered during the bid process, it is prudent for the estimator to submit an RFI

    (Request for Information) to the Owner or Agency for a clarification or revision of the contract scope

    to include any additional items that were not called out on the bid form or specifications.

    The Estimator can takeoff the project plans by utilizing several methods that can be manual tools

    including an engineer, architect or metric scale ruler or measuring wheel, and electronic devices

    consisting of a digitizer or onscreen takeoff system software. The information gathered in the

    quantity takeoff will become the basis for determining the required labor, material and equipment in

  • 8

    the cost estimate. The quantity takeoff for the new water main will start with the measurement of

    quantity of the new watermain by the lineal foot (LF). There are many varieties of material options

    for new watermain installations. The most common present day watermain materials specified by

    design engineers will include PVC, Cement Mortar Lined and Coated Steel and Ductile Iron. The PVC

    and Ductile Iron material is typically supplied in 20 LF lengths, while the steel pipe is commonly

    supplied in 40 LF lengths. Whether or not 20 LF of pipeline is being installed, the estimator must still

    include the additional material cost for purchasing a full length of material in the bid. Rounding up to

    the next full pipe section will be required to ensure an accurate material budget for the project.

    Horizontal and vertical changes in direction of the pipeline will require the use of fittings or bends,

    which are measured by the each (EA).

    Pipe fittings are typically designed as a 22, 45 or 90-degree elbow configuration for PVC, cast or

    ductile iron. However, custom offsets and elbows can be fabricated out of welded steel and could be

    potentially added to the pipe system if allowed by the project Owner. Depending on the type of

    material system utilized, a fitting may be constructed of PVC, Steel, cast or ductile iron. Specification

    requirements may require that the non-plastic fittings include special coatings that include fusion

    bonded epoxy, liquid asphaltic coat and cement mortar lining and coating. If the material is not

    supplied with the specified coating and lining, the estimator will need to source a coating company

    and provide the vendor with an estimated diameter, length and weight that will need to be coated to

    determine the appropriate cost. Often times the required coatings will be included in the suppliers

    pipe package.

    In addition to the special coatings and linings, the estimator needs to fully understand the specified

    type of connection. The various types of connection could include slip on, flanged or mechanical

    joint. In some cases the connection type will also need to be restrained with a mechanical lug

    restraint for mechanical joint fittings or restraint harness systems for push on and flanged

    applications. Many project specifications require the restraint of the fitting with a concrete thrust

    block. An appropriate quantity of short load concrete will need to be added under the backfill

  • 9

    estimate for the pipeline. Special consideration should be taken here because it may not be possible

    to place a full load of concrete for all thrust blocks in a given day. Therefore, a higher concrete unit

    cost will need to be applied. The quantity of the concrete thrust block will be calculated by the cubic

    yard (CY).

    Water systems can contain a considerable amount of valves, fittings, accessories and appurtenances

    that need to be carefully considered by the estimator. Most of these items will be taken off by the

    each (EA). While most waterworks and pipe supply houses will prepare a materials list and package

    bid for a project, it is important to carefully analyze and verify what is being quoted and avoid

    plugging the low material bid amount into the estimate without carefully analyzing what is included

    in the total quote. Often times different supply houses will be quoting different manufacturers that

    may not be an equal to what the design specification has called out for. Assuming that the low price

    pipe package with a coating or restraint system that is not an equal to what has been called out in the

    specifications could be a costly mistake