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HRP PROJECT #: 1483 <br />FROM: Joe Saggars — HRP <br />TO: Tony Kenning - DLZ <br />Reference Specifications Section: <br />Drawing No.: S2.2 <br />REQUEST: <br />REQUEST FOR INFORMATION <br />PROJECT: Calvert Street Lift Station Replacement <br />REQUEST NO.: <br />Date Sent: 2/17/2017 <br />Date Needed: ASAP <br />Date Returned: <br />The structural drawings show a 4" mud mat below 10" of compacted aggregate base. Typically mud mats are <br />for the convenience of the Contractor. HRP and Pioneer do not want the mud mat present and instead would <br />like to install 14" of aggregates; more specifically #8 gravel which is considered to be self -compacting. <br />Concerns about the mud mat include: <br />1. If the dewatering system would stop for whatever reason after the mud mat is poured and before the base <br />slab is poured, we feel the groundwater could quickly recharge and cause the mud mat to float. This <br />would require us to demo the mud mat and any aggs on top of it, re-establish grade, and re -pour and <br />replace aggregates. <br />2. The mud mat will not allow concrete form pins to be driven into the subgrade. <br />3. The mud mat acts as a liner inside the slide rail system not allowing drainage to the deep wells should <br />much accumulate in there. <br />4. The upper mud mat under the valve vault slab could channel water to the wet well foundation, where <br />there happens to be a construction joint, instead of allowing any water around or under the valve vault to <br />perk into the soils. <br />I did review the ATC geotechnical report again. The only mention of a mud map is the last sentence of <br />section 5.4 on page 10. Weaver Consulting Group is our soils engineer. They are familiar with the site and I <br />spoke to them about this issue. With the information I provided them, they feel a mud mat would not be <br />needed. <br />We do intend to perform compaction testing on the subgrade before placing the aggregate. <br />Finally, there would be a cost savings to install an additional 4" of aggs as opposed to placing lean concrete. <br />The savings that we could offer is $1,398 ($747 labor & equipment, $651 material cost difference). <br />Prepared By: Joe Saggars <br />Shipping: 5777 Cleveland Road South Bend, IN 46628-9418 Phone 574-271-7800 <br />Mailing: P.O. Box 266 South Bend, IN 46624-0266 FAX 574-271-0524 <br />