Consequent to this development is the coupling of the rural areas of Zamfara ..... will assist to modify their attitudes and encourage sustainable approach to the use of land ... Excavation of cheap sand and drainage of seasonal water ponds.
ENVIRONMENTAL DYNAMICS AND SUSTAINABLE POWER SYSTEM INFRASTRUCTURE ON THE ZAMFARA PLAINS: A LONGITUDINAL ASSESSMENT **1Edwin A. Umoh, 2Ahmed A. Lugard, 3Adamu O. Mohammed 1
Department of Electrical Engineering Technology 2 Department of Civil Engineering Technology 3 Department of Mechanical Engineering Technology Federal Polytechnic Kaura Namoda, NIGERIA ABSTRACT This paper discusses the results of a longitudinal study spanning 12 years of periodic monitoring and evaluation of the effects of the environment and engineering manufacturing standards on sustainability of electrical power distribution infrastructure on the terrains of Zamfara State, with particular reference to the Gusau-Kaura Namoda arterial route in the Northeastern axis of the State. The results of field works consisting of on-the-spot assessments, close scrutiny and data from the utility company were documented in 2002, 2007, 2013 and 2014 respectively. The summary of these findings revealed that environmental dynamics such as wind, soil characteristics, topographical variations, expanding seasonal water courseways, sheet erosions and engineering quality of power system supports on land surfaces plays critical roles in the sustainability of power system infrastructures in the localized study area. The paper advocates the entrenchment of proactive culture of preventive maintenance coupled with stringent adherence to engineering manufacturing standards and corrective policies for local land users in the context of sustainability. Keywords: Environmental dynamics, hazards, power distribution, systems, sustainability, Gusau, Kaura Namoda
1.0
INTRODUCTION
Sustainability as a concept has a longitudinal nexus which connects the activities of the past to the present and the future. Since dwindling global resources initiated the concepts of sustainability on a global scale during the early 1990s, a whole gamut of intellectual, material, economic and human resources have been ploughed into the practicality of this concept among nations. Industrialization and population explosions have continued to deplete the earth's resources, rendering the management of scarce resources to be challenging in the emerging world. On the African continent, there seem to be a less rigorous approach to the issue of sustainability due to lack of monitoring and enforcement mechanisms, lack of appreciation of the consequences of unsustainable utilization of depleting resources and a rather fatalistic approach to sustainable management among governments and the populace. A prognosis of an "unsustainable future" is by no means reassuring. During the last three decades in Nigeria, enormous fund has been sunk by the various tiers of government into the provision, stabilization and for the improvement of the utilization capacities of electrical power systems due to the strategic importance of the power sector to national transformation. Issues relating to the power sector have been a front burner due to the octopoidal influence of the sector on all other sectors of the Nigerian economy. This has led to mutually benefitting collaboration between all the tiers of government, with the view to provide electricity to the urban and rural economies of each State. Consequent to this development is the coupling of the rural areas of Zamfara North to the Nigerian electricity grid, effective from the year 2000.
Mark developmental strides were consequently witnessed in the built environment, economic and socio-educational sectors of the beneficial communities (Umoh, 2000; Alaka and Umoh, 2001; Umoh
and Ebozoje, 2008a; Umoh and Ebozoje, 2008b). However, the power system infrastructure which serves as the link between the national grid and the benefitting communities has undergone perennial instability and maintainability challenges which have affected the quantum of benefits to the service providers and consumers. These challenges have been studied and reported by researchers during the intervening years between 2001 and 2012 (Alaka and Umoh, 2001; Umoh, 2004, Umoh and Alaka, 2007). The most pronounced challenges to the sustainability of power system infrastructure on the study area are natural and anthropogenically-induced hazards. Hazards are underlying dangers associated with physical phenomena of natural, technological or anthropogenic origin that can occur at a specific site and at a defined time, producing severe effects to the people, goods, services and/or the environment (Pickering and Owen, 1994). Natural hazards encompass broad processes – geological, meteorological and biological. Geological hazards are generally of two main types- those driven by the earth’s internal energy such as earthquakes, tsunamis and volcanoes and those that results from land surface processes and are dependent on the atmospheric, climatic and weather conditions, vegetation types and cover, topography, drainage patterns and bedrock types and land use (Pickering and Owen, 1994). Commonly occurring meteorological processes in Nigeria includes floods, lighting strikes, hailstorms, rainstorms, windstorms and sandstorms. Epidemics of varying dimensions and proliferation of pests constitute biological hazards. Anthropogenically-induced hazards are those that are induced by human activities such as farming, mining and other poor land use practices (Adebimpe, 2000; Orji and Ezeabasili, 2001). In the study area, soil excavation for local production of local building materials has left deep gorges with consequences for erosions on the pole route.
Electric power infrastructure (substations, transmission lines, distribution lines and their support structures) on land surfaces are not immune from the destructive effects of natural and anthropogenically-induced hazards. Windstorms and pests are reported to have wretched havoc on power system infrastructure in the tropical and sahelian parts of Nigeria in recent years. The interplay of these hazards on transmission and distribution systems on land surfaces is illustrated in Figure 1.
Various recommendations proposed by the researchers over the years with respect to this study have been implemented by the supervising bodies leading to improvements in the status of the power system infrastructures and power delivery to consumers in the study area (Umoh and Alaka, 2007). However, climate change, seasonal environmental variations and dwindling societal fortunes of inhabitants continue to pose some intractable challenges to the long term stabilization of power system infrastructures on these terrains and this formed the basis for the longitudinal nature of this study. 2.0
THE STUDY AREA
Zamfara State, host to the study area lies in north-western Nigeria with capital at Gusau (latitude 12o 09' 51"N and longitude 06o 40' 0"E). Electricity is transmitted and distribution through three major arterial routes in Zamfara State. These are the Funtua-Tsafe-Gusau transmission route, Gusau-MaruTalata Mafara distribution route and Gusau-Kaura Namoda distribution route. These routes share similar topographical, meteorological, geomorphological and vegetational characteristics with varying degrees of harshness. The study area of this work spans 56-kilometer stretching from Gusau to Kaura Namoda in the Northeastern axis of the State. Topographically, the study area is a combination of sandy and mildly undulating plains covered by sparse tree stocks with vegetation of the hybrid southern sudan and northern guinea savannah types. Some stretch on the route are composed of scattered base rocks and shallow gorges which are dissected at different locations by seasonal 2
watercourses that formed part of the drainage patterns of the area. On this route are satellite towns like Bela, Katsaura, Kyambarawa, Kasuwar Daji, Sakajiki among others.
3.0
METHODOLOGY
Methods adopted to gather data and information include field trips, on-the-spot assessments, pictorial captures and documented data from Utility bodies. This approach was adopted to avoid hypothesizing findings and dwelling less on facts and figures.
4.0
RESEARCH FINDINGS
At the onset of the study in 2002, certain factors such as the use of poorly treated timber poles, termites and ants infestation of the timber poles were identified as contributing factors to the frequent breaking and collapse of support poles in addition to natural and engineering factors (Umoh and Alaka, 2007). At the time of the current investigation, all the timber poles have been replaced with precast concrete poles on the arterial route (see Table I). However, natural and engineering factors have persistently affected the sustainability of the poles on these terrains during the intervening years between 2007 and 2012. Among these factors are the following: I.
Pedological characteristics of soils: Samples of soils scooped at different locations on the pole route were subjected to analyses at the Department of Civil Engineering, Ahmadu Bello University, Zaria in 2002. The results showed a marked differentiation in pedological characteristics with silt and clay in abundance, indicating that the soils have low water-holding capacity. Consequent upon downpour, these soils expands and have a weakening effect on the foundation of the support poles. Accompanying storms and gust of wind subject the poles to lateral movements which induces unbalanced forces along the overhead lines, resulting in dismemberment of the crossbars, disc insulators and breaking of poles.
II.
Windstorms and rainstorms: The pole route encroaches on farmlands with sparse tree stocks. This does little to shelter the poles from the effects of wind. The impact of windstorms and rainstorms are perhaps the major extrinsic causes of pole breakages on the study area. The number of poles and types on the arterial route and study area respectively were noted in 2002, 2007 and 2013/2014 and are tabulated in Table I.
III.
Climates: The study area lies within the hot/dry climate type with two distinct seasons, the wet and the dry. The destructive effects of the local microclimates of the two seasons are complementary in nature. During the hot season between March and May, the clear sky exposes the poles on the terrains to intense insolation. This consequently gives rise to the temperature of the reinforced concrete poles. Rainfall between June and September causes differential temperature change in the concrete poles. This action causes cracks or deepening of existing cracks leaving the pole vulnerable to breakage during windstorms.
IV.
Sheet and gully erosions: Due to tree stock depletion and vegetation type, the denuded plains which provides route for the distribution systems also doubles as farmlands during the rainy season and as grazing zones for herdsmen during the hot/dry season. Owing to the rough surfaces of the impermeable basement rocks covered by thin layer of soils in some parts of the route, rainfall predictably induced a chain of raindrop and run-off erosions, which overtime leads to sheet 3
erosion. Coupled with other anthropogenic activities such as excavation of sand for traditional construction materials and exploitation of land resources by construction companies, these sheet erosion sites expand to shallow gorges and gullies. Other factors aiding erosions are seasonal watercourse floor spreading (which are noticeable at Banga and Kyambarawa villages) and ground topography (see Plates 1 and 2) Engineering and related factors which exacerbate the deleterious effects of the aforementioned factors are as follows: V.
Inferior quality of precast concrete poles and poorly treated timber poles: Factors such as the quality of concrete poles were also found to be culpable. Most of the reinforced concrete poles used in the early stage of the electrification project in 1999 developed cracks and shrinkages prior to usage. Inferior quality of precast concrete poles, a consequence of non-adherence to stipulated manufacturing standards and use of poorly treated timber poles are perhaps the intrinsic cause of pole cracking, shrinkages and breakages on the terrains (see Plate 3). Small and medium scale pole manufacturers have consistently contravened civil/structural engineering design standards for critical facilities as pressures of enforcement from engineering standard regulatory bodies are not felt. Close-up observations have confirmed that the diameters of some of the treated timber poles on the study area fell short of acceptable parameters for use in 33KV distribution systems. Table II give the number of concrete and treated timber poles on the site on the three occasions of documentation of field surveys in 2002, 2007, 2013 and 2014 respectively.
VI.
Inequality of pole span: Theoretically, if the span of conductor on each side of an intermediate pole is unequal, the pole will be subjected to an unbalanced pull in the direction of the line, as also a pole on the end of the line (Anchor, 1992; Reynolds and Steedman, 1974). The practical demonstration of this theory comes into play on the study area. The base rocks on and undulating topography of some areas like Magizawa, Kyambarawa and Kasuwar Daji settlements affected the dimension patterns of some pitted poles. Consequently, some intermediate poles have unequal span of between 27.42m to 30.47m on both sides. During windstorms, this inequality causes lateral movement of poles, resulting in breakages (See Plate 4).
VII.
Poor workmanship and poor maintenance culture: Poor assembly of cable accessories on wooden crossbars was noticeable during early years of work. Replacement of the wooden crossbar with metallic counterparts has sustained the accessories for considerable longer periods. However, maintenance culture is poor as the poles and other accessories are left unattended to, even when there are noticeable damages to their foundations or dislocation of accessories on them. Cracks are left to widen, loose joints and clamps loosen further until system collapse (See Plate 5 and 6). Sound engineering practices dictates that due to the dominant silty soil on the route, strong concrete foundation should be provided for every support pole. Unfortunately, poles are still pitted unstabilized by concrete foundations, thus making them vulnerable to slant deviation from windstorms. Investigations also confirmed the prevailing practice of replacing broken poles with substandard ones so that the recurrence of pole breakage and collapse leads to more procurement of poles, thus yielding maximum returns for the contractors and collaborators. It should be noted that between 1999 and 2011, over 400 poles is estimated to have collapsed and replaced on the route.
VIII.
Political expediency in awarding of electrification projects: The tendency of governments to make decisions on rural electrification projects without appropriate information on the environmental and the competences of the contractors to handle these projects is a major contributing factor to the sustainability challenges discussed in 4
this paper. Intrigues and collusions between local supervisory agents and contractors often lead to the use of substandard poles and power components. 5.0
CONCLUSION
The wise saying that "prevention is better than cure" holds true in engineering projects, from concept to design. As a principle, it implies the application of mitigating measures to potential hazardous events “before” and not “after” the event has occurred. Responsive strategy is a passive and temporary action with high costs in terms of money, human and material losses. On the other hand, preventive strategy is cost-effective in the long-run as it is seen not to only minimize the magnitude of damages to infrastructures but also reduces the reconstruction expenditure (www.iadb.org ; Umoh and Alaka, 2007). The challenges of sustainability uncovered by this study could have been prevented or at least minimized if "the right thing was done at the right time", by adopting manufacturing best practices in pole manufacturing and collaboration with stakeholders - engineers, manufacturers, cost managers at the planning stage. However, Lessons garnered from this longitudinal study could be imbibed by stakeholders in future expansion of electrification projects to other frontiers in the zone. The results of the study is consistent with what is obtainable on other arterial routes like the Gusau – Talata Mafara and Funtua-Tsafe-Gusau routes due to common monoclimates and topographical similarity in the State. 6.0
RECOMMENDATION
During the intervening years between 2002 and 2013, certain measures were periodically applied to mitigate the effect of environmental dynamics on the pitted poles, with minimal success, owing principally to the fact that the intrinsic factor aiding the frequent breakage and collapse of poles (i.e. poor manufacturing standards of reinforced concrete and poorly treated timber poles) are overlooked. For example, cracked and broken poles may be replaced with substandard poles and this recycles the same problems continuously over the years. Therefore, other measures necessary for sustainability are hereby recommended as follows: 1. Control of erosions Soil acts as porous medium for water storage and movement. Undulating plains are contributing factors to sheet and gully erosions on the site. In order to curtail the deleterious effect of soil erosions to the sustainability of the support poles, it is suggested that concrete foundations be laid for all the poles on the route while appropriate erosion control should be applied to decelerate the ever expanding gorges that crisscross the routes. 2. Application of manufacturing best practices by pole manufacturers It is a known fact that some concrete pole manufacturers do not adhere strictly to stipulated standards governing production of utility poles. Economic variables, not sustainability of poles are the driving force animating contractors. The “command and control” regulation where regulatory institutions dictate and enforce norms will go a long way to ensure the adoption of manufacturing best practices that will lead to vulnerability reduction. The Council for the Regulation of Engineering in Nigeria (COREN), Nigerian Building and Road Research Institute (NBRRI) and the Standard Organization of Nigeria (SON) should collaborate to hold workshops and seminars to contextually educate pole manufacturers and contractors on the imperatives of strict adherence to manufacturing best practices. 3. Corrective policies and strategies for local land users The problems of sheet and expanding seasonal water courseways are anthropogenicallyinduced by the rural people. Due to poor practices of land use, poverty and principally, the use of earth in building construction, the problems of sheet and water courseways floor spreading 5
are difficult to mitigate. The search for a viable solution must therefore begin with the understanding of these dynamics. Holding consultations with the local land owners and users will assist to modify their attitudes and encourage sustainable approach to the use of land resources around the pole route. To this end, the State and federal governments should invest in specific environment-oriented enlightenment programmes (Lugard, 2003; Umoh and Olusoga, 2002; Lugard, 2002). The State and Federal governments should equally enforce stringent measures to stem the tide of exploitation of land resources by construction companies in the study area. Excavation of cheap sand and drainage of seasonal water ponds have created deep gorges in various parts of the study areas which are noticeable around the Rawayya, and Kasuwar Daji axes.
Natural Hazards
Geological Processes
Meteorological Processes
Biological Processes
Precast Concrete Support Poles
Steel Tower Support Structures
Treated timber Support Poles
Electrical Power Transmission/Distributio n Lines
Figure 1: Natural hazards affecting transmission systems on land surfaces Source: Umoh and Alaka ( 2007)
6
Plate 1
Plate 2
Plate 4
Plate 3
Plate 5
Plate 6
Figure 2: Sample pictorial consequences of environmental dynamics on 33KV Power system Infrastructure on the Gusau-Kaura Namoda Arterial Route. 7
Sources: Field works ( 2002, 2013, 2014), Umoh and Alaka (2007) Table I: Pole statistics on study area
Year of field survey
2002
Kaura Bela - ANamoda Daza - Bela Settlement
Study Area
Source: works
2007
Total no. of poles on G-KN arterial route (Terminating at Federal Polytechnic, Kaura Namoda) Number of poles on study area Number of Reinforced concrete poles Number of treated wooden poles
20132014 Kaura Namoda Gusau
964
964
964
355 314 41
591 544 47
900 900 Nil
2013/2014), Umoh and Alaka (2007)
Table II: Engineering Parameters of pitted support poles Average height of poles 10.06m Pit depth of erected poles 1.83m Average span between intermediate poles 27.42 - 30.47m Average density of wooden poles N.A. Type of transmission line conductor A.S.R.C. Transmission line voltage level 33KV Estimated number of collapsed/broken poles on the route 400 (approx) (1999-2013) Source: Directorate for Rural Electrification (2007), Umoh and Alaka, 2007; Field works, 2008-2013
8
Field (2002,
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