2-142 SECTION 250 – CONSTRUCTION VIBRATION AND CRACK MONITORING
250.01 DESCRIPTION . This work shall consist of conducting construction condition surveys,
developing and implementing a construction vibration monitoring plan, installing monitoring equipment, and performing monitoring of construction activities.
250.02 GENERAL REQUIREMEN TS. Structures identified in the Contract shall be monitored as
specified herein, however, in accordance with Subsection 107.11 , the Contractor shall be responsible for all damage caused by their activities, regardless of whether or not the damaged structu re or infrastructure was identified as being susceptible to damage in the Contract. The Contractor shall notify residents and owners of the buildings identified in the Contract of the required monitoring and inform them of the scheduled activities. At a mi nimum, notification shall include a certified letter. The Contractor shall furnish to the Engineer a list of those contacted and proof of notification. The Contractor shall maintain a log of all vibration related complaints, contact information for complai nant, and actions taken, and shall furnish copies to the Engineer upon request.
250.03 EQUIPMENT . The Contractor shall furnish, maintain, and operate vibration monitoring
equipment, such as seismographs and crack displacement monitoring gauges . Seismograp hs shall be capable of measuring, recording, and producing a hard copy of the frequency and peak particle velocity in three mutually perpendicular components of vibration, the vector sum of these peak particle velocities, and the frequency history of the v ibrations. Instruments that only record vector sum measurements are not acceptable. These instruments shall be capable of measuring linear scale (dB -L) sound levels and be capable of continuously recording the peak particle velocity and providing a permane nt record of the entire vibration event. All monitoring equipment shall be powered with rechargeable batteries. Extension geophone and microphone cables may be necessary so that the instruments can be placed within structures if outside temperatures drop below 32°F. Crack displacement monitoring gages shall be capable of monitoring horizontal and vertical movement with an accuracy of 0.04 inches.
250.04 PERSONNEL PREQUALIFICATION . The Contractor shall provide the services of an
independent qualified engineering consultant. The engineering consultant used shall be subject to the approval of the Engineer. 2-143 The engineering consultant shall be responsible for the vibration and crack monitoring for construction activities. They shall conduct th e construction condition surveys, develop the construction vibration monitoring plan, conduct the deployment and operation of all monitoring equipment, and be available to discuss vibration results at the request of the Agency. The Contractor shall submit the following information regarding the engineering consultant’s qualifications:
a.Documentation showing that the engineering consultant has directly participated in three projects in the past 5 years where they have successfully developed vibration cri teria and monitored construction activities on projects similar to the scope of the current project. The documentation shall contain a description of the projects, the names of the general contractor and the owner, and current contact information of a repr esentative of the construction manager or project owner.
b.A resume of the engineering consultant showing at least 10 years of experience in seismic monitoring. The Contractor shall submit this information to the Engineer for review, evaluation, and app roval prior to submitting detailed information as required in Subsection 250.06 . The Engineer will render a decision within 7 calendar days after receipt of the submission.
250.05 CONSTRUCTION CONDITION SURVEYS . The engineering consultant shall conduct a pre-
and post -construction condition survey of any buildings, structures, or utilities identified in the Contract. Additional buildings, structures, or utilities not identified in the Contract may require a survey, as identified by the engineering consulta nt or as directed by the Engineer. The engineering consultant shall submit the construction condition survey results as outlined in Subsection 250.06 .
250.06 SUBMITTALS. The Contractor shall submit to the Engineer, in accordance with Subsection
105.06 , the following information for completing the work. The Contractor is entirely responsible for the
work associated with these submittals.
a.Pre-Construction Submittals . The contractor shall submit the following information at least 21 calendar days prior t o the start of construction . Construction shall not begin until the submittals have been approved in writing by the Engineer.
1.Pre-Construction Condition Survey Report . The pre -construction condition survey shall include, but is not limited to:
a.A summary naming the person who performed the survey, including the date and time of the survey. 2-144 b. A description of all structures, utilities, and other facilities identi fied in the Contract and in the judgment of the engineering consultant requiring a pre -construction condition survey. Particular attention shall be given to historic structures, structures in poor condition, structures supported by vibration sensitive mate rials which could cause settlement or loss of support, and structures which contain sensitive equipment or processes.
c.Location and contact information for the owners and occupants of all facilities contacted and surveyed.
d.Documentation of the aesth etic and structural condition through observations, actual measurements, plan sketches, photographs, digital recordings, and any other data deemed appropriate. Photos and digital recordings shall contain an accurate date stamp.
2.Construction Vibration and Crack Monitoring Plan . The Contractor shall submit a detailed plan for construction vibration monitoring. This shall include, but is not limited to:
a.A description of proposed construction methods, including amplitude descriptions of each v ibration producing activity, and a vibration monitoring plan for each activity.
b.A description of the monitoring equipment intended for use.
c.Certificates of calibration for all monitoring equipment. The records shall show that the monitoring equipmen t has been calibrated on an approximate 6 month interval.
d.Proposed vibration and crack monitoring limits for each piece of monitoring equipment for each vibration producing activity.
e.Proposed locations of seismographs and crack displacement monitor ing gauges. Locations shall be recorded in degrees latitude and longitude and included in a plan view.
f.Baseline monitoring data, recorded for at least 7 calendar days prior to vibration producing activities to establish background conditions.
g.Descri ption of the process which will be used to verify that the monitoring equipment will function as planned before starting work and the process which will be used to verify that the monitoring equipment remains in calibrated working order. 2-145 h. Procedures to be implemented if it is determined that the proposed construction activity cannot be reasonably implemented without exceeding vibration limits.
i.Procedures to be implemented if the vibration limit is reached or if damage is observed regardless of vibra tion limits being exceeded.
j.Examples of all forms used in the Contractor’s submissions. Individual forms may require revision for the Agency’s approval.
b.Monitoring Data and Reporting . The engineering consultant shall submit monitoring data daily when vibration producing activities are in progress. This shall include, but is not limited to:
1.Summary report from each seismograph, including, but not limited to:
a.Instrument and lo cation.
b.Peak particle velocity and frequency of the peak.
c.Peak particle displacement.
d.Peak acceleration.
e.Peak vector sum.
f.Relationship to baseline data collection.
g.Confirmation that the vibration data shows conformation with the vibr ation limits.
2.Measurements from crack displacement monitoring gauges.
3.A dated and signed copy of records of all seismographs and crack gauges readings.
c.Vibration Exceedance Report . If the vibration limit is reached or exceeded, or there are signs of damage to surrounding buildings and structures, the Contractor shall submit a vibration exceedance reports for approval before vibration producing activities can resume. This report shall include, but it is not limited to:
1.Cause of the exceedance.
2.Proposed corrective action for future construction activity.
3.Proposed corrective action to address any damage that occurred. 2-146 (d) Post-Construction Condition Survey Report . The contractor shall submit the following information not more than 21 calendar days after vibration inducing activities are completed. The post - construction condition survey shall include, but is not limited to:
1.A summary naming the person who performed the survey, including the date and time of the survey.
2.Location and contact information for the owners and occupants of all facilities surveyed.
3.Documentation of all facilities surveyed during the post -construction condition survey, including documenting the aesthetic and structural condition through observations, actual measurements, plan sketches, photographs, digital recordings, and any other data deemed appropriate. Photos and digital recordings shall contain an accurate date stamp.
250.07 MONITORING CRITERIA . The engineering consultant shall be responsible for installing
monitoring equipment and performing monitoring of background and construction activities .
a.The engineering consultant shall be responsible for placing the monitoring equipment at locations designated in the construction vibration monitoring plan.
b.The monitoring vibration measuring equipment shall be calibrated within 6 months of the time of use and operated by properly trained personnel.
c.Additional monitoring equipment may be required at the discretion of the Engineer and at no cost to the Agency.
d.In the event that the Contractor chooses to have concurrent vibration producing activities at more than one location, the Contractor shall notify the Engineer prior to the com mencement of such activities. The Engineer may require additional monitoring equipment at each location depending on site parameters.
e.No vibration producing activities may be started until the appropriate monitoring equipment is installed and function ing as witnessed by the Engineer.
f.The Contractor shall be responsible for monitoring equipment maintenance. If the Contractor does not maintain an amount of monitoring equipment sufficient to monitor the vibration producing activity, the Engineer may direct that all vibration producing activities cease until a sufficient amount of monitoring equipment is present. 2-147 (g) The Contractor shall immediately cease work if the approved vibration limit is reached or exceeded. In the event of an exceedance the Engineer shall be notified immediately. In the event of work being stopped, the Contractor shall submit a vibration exceedance report as outlined in Subsection 250.06(c) . In order to proceed with any further vibration producing activities, written permiss ion shall be obtained from the Engineer.
h.The Engineer may, at any time, halt construction if there are signs of damage to surrounding buildings and structures.
250.08 METHOD OF MEASUREMENT . The quantity of Construction Vibration and Crack Monitoring
to be measured for payment will be on a lump sum basis in the complete and accepted work.
250.09 BASIS OF PAYMENT . The accepted quantity of Construction Vibration and Crack Monitoring
will be paid for at the Contract lump sum price. Payment will be full c ompensation for developing the construction vibration and crack monitoring plan, performing the construction condition surveys, implementing the plan, including making all submittals, installation of monitoring equipment, recording and submitting daily mon itoring reports, making any necessary modifications during construction and for furnishing all labor, tools, equipment, and incidentals necessary to complete the work. Partial payments will be made as follows:
a.The first payment of 35% of the Contract unit price will be made once the construction vibration and crack monitoring plan is approved.
b.The final payment of 65% of the Contract unit price will be made once the post -construction condition survey report is approved. Payment will be mad e under: Pay Item Pay Unit 250.0100 Construction Vibration and Crack Monitoring ................................ ......... Lump Sum 2-148 This Page Intentionally Left Blank 3-1 DIVISION 300 SUBBASE AND BASE COURSES SECTIO N 301 – SUBBASE 301.0 1 DESCRIPTION . This work shall consist of furnishing and placing one or more courses of approved gravel, crushed gravel, dense graded crushed stone, or other proportioned material on a prepared surface or at other locations. 301.0 2 MATERIALS . Materials shall meet the requirements of the following subsections: Coarse Aggregate for Concrete ................................ ................................ .................. 704.02 Gravel for Subbase ................................ ................................ ................................ .....704.04 Crushed Gravel for Subbase ................................ ................................ ...................... 704.05 Dense Graded Crushed Stone for Subbase ................................ ................................ 704.06 Processed Glass Aggregate ................................ ................................ ........................ 704.20 Recycled Concrete Aggregate ................................ ................................ .................... 704.21 At the option of the Contractor, unless otherwise specified in the Contract, processed glass aggregate (PGA) meeting the requirements of Subsection 704.20 or recycled concrete aggregate (RCA) meeting the requirements of Subsection 704.21 may be used to partially replace natural aggregate in materials specified to meet the requirements of Subsection 704.04 , Subsection 704.05 , or Subsection 704.06 . PGA subbase blends shall not contain more than 20% PGA by weight. RCA subbase blends shall not contain m ore than 25% RCA by weight. In no case shall PGA and RCA be combined in subbase. The final blend shall conform to the specified gradation for the subbase material. The blending process shall be complete to ensure that as thorough a distribution and as unif orm a mixture as practicable has been obtained. In -place blending of PGA with other materials will not be permitted. When specified for use on the project or as directed by the Engineer, RAP subbase shall include milled grindings which have been screened or crushed by the Contractor such that 100% pass the 1 -1/2 inch (37.5 mm) sieve prior to blending. The grindings shall be blended in equal proportions (50% by weight) with material meeting the requirements of fine graded crushed gravel for subbase as specified in Table
704.05 A.
Source: Vermont Standard Specifications for Construction, 2024 Edition. Pages 282–288 of 1,380.