The Link between Permeable Interlocking Concrete Pavement (PICP) Design and Nutrient Removal

Bodi Liu,Neil Armitage

doi:10.3390/w12061714

Abstract

The construction of ‘hard’ impermeable surfaces in urban areas results in the increased flow of stormwater runoff and its associated pollutants into downstream receiving waters. Permeable Pavement Systems (PPS) can help mitigate this. The most common type of PPS in South Africa is permeable interlocking concrete pavement (PICP), but there is currently insufficient information available on the relative treatment performance of different PICP designs. This paper describes an investigation into the performance of ten different PICP systems constructed in the Civil Engineering Laboratory at the University of Cape Town for the treatment of various nutrients commonly found in stormwater runoff. It was found that removal efficiencies ranged from 27.5% to 78.7% for ammonia-nitrogen and from −37% to 11% for orthophosphate-phosphorus; whilst 4% to 20.2% more nitrite-nitrogen and 160% to 2580% more nitrate-nitrogen were simultaneously added. The presence of a geotextile resulted in higher ammonia-nitrogen removal efficiencies but also higher nitrate-nitrogen addition than those cells without—with small differences between various types. The cell with a permanently wet ‘sump’ had the highest nitrate-nitrogen addition of all. Lower pH results in higher nitrate-nitrogen concentrations, whilst the electrical conductivity strongly depends on the length of the periods between rainfall ‘seasons’, decreasing rapidly during wet periods but increasing during dry periods. Paver type also had a minor impact on nutrient removal.

Highlights

Rapid urbanization in the 21st century has resulted in much land becoming impervious owing to the construction of roads, parking lots, driveways, and buildings
17,600 mm/h, this will not be discussed here as they merely proved the excellent performance of the permeable interlocking concrete pavement (PICP) cells and are unlikely to have any impact on the nutrient removal
It is hard to comment on whether the presence of a geotextile had an impact on the orthophosphate-phosphorus removal in the field study. This investigation examined the relative impact of different designs of PICP on water quality improvement

Summary

Introduction

Rapid urbanization in the 21st century has resulted in much land becoming impervious owing to the construction of roads, parking lots, driveways, and buildings. The traditional approach to urban drainage is to convey stormwater runoff in pipe and canal networks to the nearest receiving water bodies as quickly as possible. This, leads to increased runoff flows and volumes resulting in the erosion of watercourses whilst stormwater pollutants, such as heavy metals, hydrocarbons from motor vehicles, suspended solids, and nutrients, such as nitrogen and phosphorus, cause a deterioration in water quality. In many countries, including South Africa, a more sustainable approach for stormwater management termed Sustainable Drainage Systems (SuDS)—called Low Impact Development (LID). As one of the source controls in SuDS, permeable pavement systems (PPS) offer a potential solution to the problem of increased surface runoff and decreased stream water quality by promoting the infiltration of stormwater runoff through the wearing course and some treatment through the underlying aggregate layers [5]. PPS can be adapted to make an effective stormwater harvesting and storage device for

Methods

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Conclusion