Elwood IL RFI 03.31.25.pdf
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- Solicitation number
- 25-21003734
About this file
This document is a Request for Information (RFI) for a ground rod spacing issue related to a fence replacement project at the Elwood, IL ARSR (Air Route Surveillance Radar) site. The RFI addresses technical specifications for ground rod installation, specifically questioning the current requirement of ground rod spacing less than 100 feet apart, which differs from the typical nominal spacing of two to three times the rod length (20-30 feet). The document references FAA-STD-019F and notes that local ground rod resistance in Illinois is between 20-35 ohms, prompting a request to understand if chemical soil enhancements could be used to meet the less stringent spacing requirements while maintaining adequate electrical grounding for the security fence.
The response indicates that the fence falls under special conditions, and while the original design followed more stringent spacing guidelines, there is openness to potentially adjusting the design if data suggests the current proposed spacing (less than 100 feet) might not provide adequate protection. The RFI demonstrates a proactive approach to clarifying technical specifications and seeking optimization of ground rod installation methods to minimize excavation and earthwork while maintaining proper electrical safety standards.
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Elwood, IL RFI – 03/31/2025
1. There is a question that keeps coming up regarding the spacing of the ground rods and the answer we believe is a bit misleading. We want to provide the best possible service to the government and to we cannot do so without proper clarification.
Below is a summary of what we believe to be the proper spacing and or alternative to the < 100ft ground rod spacing per FAA Guidelines and Regulations.
Referencing FAA-STD-019F
4.4.4.1 Ground Rods (b) provides requirements for Spacing...Nominal Spacing between ground rods is between two and three times the rod length which is 20ft -- 30ft the current specs, blueprints and answers from RFI's state that "Ground Rod Spacing should be no greater than 100 feet, spacing to vary 10% - 20 %"
However, during the initial site visit, we noticed that the existing ground rod installation in place has ground rods installed every 30feet. Here in Illinois ground rod resistance is between 20-35ohms, hence the reason for additional ground rods 4.4.4.1 (b)
To minimize excavation and earthwork, can we adhere to the new ground rods spacing requirements specified in the blueprint/RFI/Spec sheet (less than 100 feet apart) using chemical soil enhancements to lessen ground rod resistance ?
I see the concern there, for a normal grounding system for a building with electrical equipment, et; the nominal spacing would be two to three times the length of a ground rod as specified in section 4.4.4.1, but for a chain link security fence like that, that configuration tends to be an overkill, hence 100 feet as described in section 5.3.8.1 ( FAA-STD-019F). The fence basically falls under special conditions. It sounds like the original fence design went by section 4.4.4.1, but if they have data to suggest section 5.3.8.1 might not be adequate for this site, we can take that into consideration and make changes to the current design.
File details come from the government source that posted it. Updated .