Q-A _revised_10-14-15.pdf

DTFH6815B00012 Revised 10/14/15

CO ER 94/81/106(1)

BOULDER COUNTY LEFTHAND CANYON DRIVE

9/30/15

QUESTION #1

Will the excavation and embankment at each station from the cross sections be made available?

Response: See amendment A001.

10/7/15

QUESTION #2

Is recycled concrete and/or recycled asphalt an acceptable material for Aggregate Base?

Response: No

QUESTION #3

Is recycled concrete an acceptable material for Riprap?

Response: No

10/12/15

QUESTION #4

Pg 117 of FP (b) middle of the paragraph “Document the natural frequency of each affected structure or feature.” Question: I do not understanding this statement, can you please explain?

Response: Establish a baseline for in-place monitoring equipment prior to the blast. This can be conducted immediately prior to the blast.

QUESTION #5

Pg 117 of FP (d) forth sentence reads: “Place at least one station on the structure.” Question: Will it be allowable to place one station (seismograph) in a straight line and in-between the blast and the nearest structure? Instead of placing the station (seismograph) on the structure?

Response: Pg 117 (d) second sentence: “Locate monitoring equipment as directed by the vibration specialist.” Seismograph placement is based on findings of the pre-blast survey and proposed blast plan.

QUESTION #6

Pg 117 of FP sentence below (d): ”Ensure blasting operations incorporate collected data and findings from the vibration monitoring by having the vibration specialist interpret seismograph and air-blast records. Question: In regard to interpreting the vibration and air-blast records, can the seismograph specialist be an employee of the drilling & blasting contractor?

Response: Yes. Submit qualifications.

QUESTION #7

Does the vibration specialist have to observe each blast event?

Response: No

QUESTION #8

Pg 117 of FP, 205.07 Test Blast: “Before beginning full-scale drilling and blasting, demonstrate adequacy of the site-specific blasting plan by drilling, blasting and excavating a test blast of up to 100 cubic yards…etc.” Question: Can the test blast volume be increased to 300 – 400 cubic yards?

Response: See amendment A003.

QUESTION #9

Pg 118 of FP second paragraph: “Record and maintain a log of each blast hole drilled identifying the depth, color…etc.”. Question: Will drillers logs be required?

Response: See Amendment 003.

QUESTION #10

Pg 119 of FP seventh paragraph: “Offset lifts up to 24 inches horizontally to allow for drilling equipment clearance.” Question: Can the offset lift be increased to 36 inches for drill clearance?

Response: See Amendment A003.

QUESTION #11

Pg 120 of FP (1) Presplitting: “Do not presplit final slopes and rock faces”. Question: Will presplit be utilized to control the final cut slopes? If not, what control drilling and blasting method should be used?

Response: SCR 205.01 reads: “Controlled pre-split blasting will be required for all excavated slopes where rock blasting is required”

QUESTION #12

Pg 120 of FP 205.09 Reporting, (b) Vibration and air-blast reporting. “Submit a vibration and air-blast report within 3 days of a blast…etc.” Question: Does the report need to be a full wave-form report or does the CO require just the peak particle velocity (inches per second) and air-blast (Db) readings? If so, can the readings be documented on the Final Blast Report for the CO’s review?

Response: The peak particle velocity (inches per second) and air-blast (Db) readings can be documented on the final blast report for the CO’s review. However, if requested, the full wave-form report should be made available.

QUESTION #13

Bid Schedule “Z”, it appears some asphalt items are missing. Does not have line items anti-strip additive, prime coat and tack coat.

Response: See Amendment A003.

QUESTION #14

In all asphalt bid item descriptions, it states to use ½” asphalt mix or ¾” asphalt mix. Does this mean we can use either or a combination of?

Response: Either

QUESTION #15

All schedules to be completed by September 30th, 2016?

Response: Yes

QUESTION #16

Asphalt: Is a percentage of RAP allowed?

Response: Yes, See subsection 401.03(a) of the FP.