Physicochemical Characterization of Horizontal Directional Drilling Residuals

Joshua Daniel,Chad Penn,Hailin Zhang,João Antonangelo

doi:10.3390/su12187707

Abstract

Horizontal directional drilling (HDD) is a trenchless technology mainly used for the installation of gas, sewer lines, and fiber optic cables. Spent HDD fluid is a by-product of the boring process. However, little is known of its constituency, although the land application of spent HDD residuals would be an economical and less time-consuming method of disposal. Physicochemical analysis of spent HDD residuals from broad geographic regions was conducted to determine if the land application would be an environmentally safe option for disposal. Fifty-eight HDD samples were collected from 26 states throughout the United States. After separation of the liquid and solid portion, the materials were assessed for carbon (C), nitrogen (N), plant nutrients, soluble and total trace metals, total dissolved solids, sodium adsorption ratio (SAR), and potential “leachable metals”. All trace metal concentrations in the digested solid portion were well below the limits for biosolids set by the EPA 40 Part 503 rule for land application. Metal concentrations did not exceed the limits of drinking water standards. Besides the total amount of solids, there was nothing chemically limiting HDD residuals from land application. However, if boring through soil with suspected contamination, testing the residual before the application is recommended.

Highlights

A wide variety of waste materials and by-products have been land-applied as soil amendments to improve soil quality for centuries [1]
The electrical conductivity of the residuals ranged from a low of 118 μS cm−1 to a high of 3950 μS cm−1 with mean and median values of 1198 and 1124 μS cm−1, respectively (Table 1)
Using an application rate of 112 metric tons of solids ha−1, the largest loading rate would apply 3723 kg ha−1 salt. This is well below the limit of 6724 kg total dissolved solids ha−1 allowed by the OCC for the land application of water-base drilling mud from oil and gas exploration (Oklahoma administrative code and register, Title 165:10-7-19)

Summary

Introduction

A wide variety of waste materials and by-products have been land-applied as soil amendments to improve soil quality for centuries [1]. Often the sources of these waste residuals are agricultural, municipal, and industrial wastes or by-products. These materials, in their broadest sense, vary widely in terms of their overall beneficial and environmental impacts. Because of environmental concerns and economic restraints in regards to landfilling and incineration, public interest in land application of waste is continuing to grow [3]. Perhaps the most important factor in regards to the land application of agricultural, municipal, and industrial by-products is earning the public’s trust concerning safety. Gaining the public’s trust will require waste management in such a way that protects human and animal health as well as safeguards soil and water resources, and maintains a quality ecosystem for the long term [4]

Objectives

Methods

Results

Discussion

Conclusion