Saturated hydraulic conductivity (Ks) is an important soil parameter that is difficult to measure, especially in an anisotropic medium. Many methods for determining Ks have been developed over time, but taking different water flow directions into consideration is possible in only a few of them; furthermore, these few methods cannot be universally applied. The method proposed here allows Ks to be determined in both anisotropic and heterogeneous soils. It involves testing cubic soil cores using the Wit apparatus. To use this permeameter for samples that are not cylindrical in shape, it is necessary to prepare special measurement equipment. One such set of equipment developed consists of the soil cube (four sides of which are sealed with gypsum), which is placed in a protective box and connected to a measurement cuboid. In the soil sample, water always flows from the bottom up during the test, but it is possible to turn the sample over and thus analyze different water flow directions. The soil cubes needed are small (0.05 by 0.05 by 0.05 m), but for a particular set of conditions only 15 cores extracted from each sampling location was found to be enough to determine Ks with a precision of ±15%. Results yielded by the presented method appeared to be comparable with Ks values obtained using a constant‐head permeameter with cylindrical soil cores. The advantages of the proposed technique are the possibility of measuring Ks in both horizontal and vertical directions using the same sample, a lack of leakage along the edges of a sample, the ease of soil sample extraction, and the technique's use of inexpensive materials.

Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl IntroductionThe use of water supply pipes all over the world has always been accompanied by breakages and leakages. What can reduce a number of damages is skilful management of a water supply system and proper maintenance. It is, however, impossible to entirely eliminate such incidents as, most often, they occur randomly [5,7,24]. They can result in financial and social losses [7,8,25,28]. Moreover, leakages can pose a threat to the safety of people and property particularly in urban agglomerations, where water supply systems are located within roadway, constituting an element of an underground utility, as well as in areas of compact settlement [13]. The threat emerges as a result of the particles being washed out from the soil skeleton during the breakage of an underground pipe which can lead to the formation of empty spaces beneath the ground surface and contribute to the creation of depression or holes in the Earth's surface (suffosion processes) [1,4,9]. Such incidents took place worldwide and produced detrimental social and economical effects [22]. Occurrence of internally unstable soils, especially in the range of the loess plateau [2] as well as a high failure intensity rate of water supply systems, compared to other countries [15,16,18,19], are factors which increase the risk of the emergence of such a problem in Poland. IwAnek M, kowAlskA B, Hawryluk e, kondraciuk k. Distance and time of water effluence on soil surface after failure of buried water pipe. laboratory investigations and statistical analysis. eksploatacja i niezawodnosc -Maintenance and Reliability 2016; 18 (2): 278-284, http:// dx.doi.org/10.17531

One of main problems that exploiting water supply network companies have to deal with is a secondary contamination of water transported by a distribution system. That problem has escalated after the political system transformation in 1989, which turned out to be typical for Central and East Europe countries. In this paper, selected causes and the scale of this phenomenon is shown. Attention was paid to the evolutionary changes which have occurred in water supply networks through last 20 years. At first, oversizing of water supplied networks was assumed as the main reason of the recontamination, as a result of an essential decrease of industrial and individual customer's water demand. Gradually, other factors were noticed, such as a dynamic increase of exploited water supply pipe's length and material's influence. As additional factors, the authors also acknowledge results of actions taken in order to raise water supply enterprises efficiency -especially with connecting small, local networks into group systems.Presented considerations and analysis were based on an available domestic literature and survey research undertaken in Polish water supply companies in the years 2010-2012. The authors also present exemplary results of their own research, realized in selected water supply systems of different sizes. This research illustrate an influence of the pipes' material (PVC and PE), but also the unwelcome effects of connecting local water supply networks into one group system.

The result of a breakage of a buried water pipe is the water movement in soil, which can cause that fine soil particles are washed out from the solid matrix and transported through pores (suffosion process IntroductionDepressions or holes creating on the soil surface as a result of suffosion can be very dangerous, especially in urban areas. It is widely known that the most hazardous phenomena of this kind relate to water-engineering structures [1,2,3]. It stems from the fact that failures and damages of pipes occur in water, sewage and storm water systems all over the world during their operation [4,5,6]. Even the high-tech methods of pipes condition assessment do not enable to prevent leakages occurrence, because of their random character and multiplicity of their reasons [7,8,9]. Still insufficient knowledge about them [10] is caused by many different, both static (pipe and soil parameters) and dynamic (hydraulic working conditions), factors [11,12,13,14,15]. Creation of suffosion holes is a phenomenon specially typical and onerous for water supply systems of a high intensity rate placed in internally unstable soils. The result of a breakage of a buried water pipe is the water movement in soil, which can cause that fine soil particles are washed out from the solid matrix and transported through pores (suffosion process) [16,17,18,19,20,21]. As a result, depressions or holes can form on the soil surface. Holes creating on the soil surface by water outflowing after a failure of a buried pipeline (suffosion holes), are in different shapes and sizes.Recognition of factors influencing holes shapes and sizes would facilitate the prevention of hazardous suffosion effects connected with failures of water distribution systems. In the range of the presented article, the influence of pressure head in a water pipe on dimensions of suffosion holes was analysed. The basis of the analysis was results of laboratory investigations of the controlled leakage from a buried water pipe.

Anisotropy of saturated hydraulic conductivity (Ks, m s‐1) is a major input datum required for the modeling of saturated and unsaturated water flow in soils, significantly improving the reliability of the models. But, there are several known literature reports presenting positively verified examples of modeling of infiltration in horizontally layered small‐scale soil profiles without taking anisotropy into consideration. The objective of this paper is to analyze the influence of implementing the anisotropy ratio to the two‐dimensional mathematical model of unsaturated flow in a selected small‐scale multilayered soil profile on the possible improvement of calculations results. Two methods of soil sampling for anisotropy measurement were considered—small cylinder and cubic sampling. Our numerical model reflected the profile of a single bench terrace equipped additionally with draining sand ditch, located in Olszanka, Poland. The simple regression analysis indicated that implementing the ratio of anisotropy of saturated hydraulic conductivity to the mathematical model of variably saturated water flow in the studied horizontally layered soil profiles did not result in more precise effects of time‐variable soil moisture calculations (R2 = 0.773–0.883, P = 0.05). Moreover, results of the statistical calculations for volumetric water content and vertical flow velocity, assuming isotropic and anisotropic medium with anisotropy coefficient obtained on the basis of cylindrical and cubic samples, appeared to be comparable; the notable differences were observed only in the case of calculated horizontal flow velocity.

Abstract. The analysis of water losses should precede the decisions on repairing or modernizing a water network. Water balance and water losses indicators established by the International Water Association (IWA) standards can constitute the basis for the analysis. The methods recommended by IWA are gaining increasing popularity in many countries, including Poland. The aim of the paper is the analysis and comparison of water losses in two middle-sized water distribution systems during the period of 10 years. The compared networks are similar in respect to many parameters, including water intensity indicator value (circa 48 m 3 /d/km). Analyses were conducted on the basis of water losses indices recommended by IWA, such as Real Losses Level per connection per day (RLL), Non-Revenue Water Level (NRWL) and Infrastructure Leakage Index (ILI). The results indicated that water losses in both systems are lower than in the literature data for other similar networks.

W pracy przedstawiono wyniki badań eksploatacyjnych awaryjności sieciowych obiektów kanalizacyjnych tworzących systemy odprowadzania ścieków w dużym mieście. Badaniami objęto 1568 km sieci kanalizacyjnych, w tym sieć ogólno-spławną około 429 km, sieć sanitarną około 660 km, sieć deszczową około 470 oraz przewody tłoczne około 9 km. Głównym celem badań była ocena i wizualizacja awaryjności sieci kanalizacyjnych i kanałów na mapach numerycznych miasta. Oceniono wpływ rodzaju sieci, wymiaru (poniżej i powyżej 300 mm) i materiału kanałów (kamionka, beton i żelbet, żeliwo szare, PVC), pory roku, rodzaju gruntu oraz występowania wód gruntowych na awaryjność obiektów sieciowych. Na potrzeby analiz awaryjności wyodrębniono odpowiednie obiekty badawcze. Obiekty takie są podstawą tworzenia bazy danych w GIS do celów zarządzania awariami. Zamieszczono fragment planu siatki ulic ze wskazaniem miejsc awarii wraz z ich opisem. Zdefiniowano trzy grupy zdarzeń awaryjnych, tj. zamulenie -pełne zablokowanie przepływu, niedrożność -częściowe blokowanie przepływu, i inne zdarzenia, głównie mechaniczne uszkodzenia. Analiza uzyskanych wyników pokazała, że blisko ¾ wszystkich zarejestrowanych zdarzeń to niedrożności powodujące zakłócenia w przepływie, ale nieblokujące go całkowicie. W badanym okresie zaobserwowano tendencję malejącą w zakresie awaryjności badanych sieci kanali-

Celem niniejszego artykułu jest analiza pracy wybranego wodociągu grupowego w latach 2003-2012 w aspekcie strat wody. Badany wodociąg zasilany jest z czerech ujęć zlokalizowanych w sąsiadujących z sobą miejscowościach. Łączna długość sieci wraz z przyłączami wynosi 489 km. Przewody wykonane są głównie z polichlorku winylu oraz polietylenu dużej gęstości. Obciążenie poszczególnych stref jest nierównomierne i waha się od 5,63 m 3 /(d•km) w strefie B do 16,45 m 3 /(d•km) w strefie A. Średnia produkcja wody w latach 2003-2012 wynosiła 598794,2 m 3 /rok. W pracy zastosowano standardowe metody badawcze-bilansowanie według International Water Association oraz metodę wskaźnikową. Wyznaczono procentowy wskaźnik strat wody (S), jednostkową objętość strat przypadającą na jednego mieszkańca (q STR), jednostkowy wskaźnik strat wody (q sj), wskaźnik jednostkowych strat rzeczywistych, przy co najmniej 20 przyłączach przypadających na 1 km sieci (RLB), wskaźnik przecieków infrastruktury (ILI) oraz wskaźnik objętości wody niedochodowej (NRWB). Badania przeprowadzono na podstawie danych uzyskanych z przedsiębiorstwa wodociągowego. Najwyższą wartość większości wskaźników strat wody zaobserwowano w 2005 roku, później nastąpił spadek ich wartości i w 2010 roku ponowny wzrost. Niska wartość ILI, we wszystkich strefach poniżej 1,5, świadczy o bardzo dobrym stanie technicznym sieci. Najwyższe straty wody zaobserwowano w strefie zasilanej z ujęcia B. Również dla tej strefy wartość wskaźnika RLB i NRWB jest najwyższa. Wyznaczone wskaźniki start wody są porównywalne do opublikowanych wartości, uzyskanych dla innych systemów wodociągowych i wskazują na zadowalający stan badanej sieci.