DISPOSAL OF WASTE WATER IN ECOLOGICALLY
SENSITIVE ENVIRONMENT OF LIGHTHOUSES
Author:
Neven Šerić, B.A.-Econmics
Contributors
Mirogoj Ikač, B. Sc.- Civil Engineering
Zrinka Vidović, B.A.
Plovput d.o.o. Split, Obala Lazareta 1 Split, plovput@ st.tel.hr
Summary: This project related to the revitalization of non-functioning lighthouses, initiated
by Plovput Ltd., Split, includes models applied in the search for an optimal solution for waste
water disposal at the lighthouses. By analyzing the experiences obtained from similar cases
and by adapting it to the specific conditions in the Adriatic Sea, a closed sea with weak and
non-uniform sea currents, this project envisages the excavation of infiltration wells within the
waste water disposal system. Those wells are dimensioned so that their shape and capacity
depend upon the soil geomorphology, the computed daily waste water quantity and the
characteristic features of the sea bed, sea currents and winds at each lighthouse. The solution
of all problems encountered in the field of environmental engineering should be approached
by solving actual cases since there are no general solutions. Hence, the main objective of this
paper is to present an approach to the problems from this domain illustrated by one actual
example.
Key words: lighthouses, revitalization, waste water, disposal, infiltration wells.
1. SEARCH FOR AN OPTIMAL SOLUTION FOR WASTE WATER DISPOSAL
WITHIN THE STONE LIGHTS PROJECT
1.1. Background
As the caretaker of Croatia’s lighthouses, Plovput initiated the Stone Lights Project, in order
to find a way to stop the deteriroration of these buildings which are no longer used for their
original purpose. Before the automation of the lighthouses, they also served as residences for
the keepers and their families. In the mid-1990’s the Pharos Project was an attempt to solve
the financing of the maintenance of these 19th century structures built during AustroHungarian rule. The Pharos project offered long-term rental rates for the lighthouses in return
for renewal and upkeep. However, the Project was abandoned due to the following reasons:
-
financially inadequate bids which did not ensure that the lease-holders would satisfy the
proposed obligations;
questionable quality of ecological standards to be carried out by the lease-holders; and
inadequate support of the project by various public institutions in Croatia.
1
By the end of the 1990’s Plovput, Ltd. initiated a new project, Stone Lights, based on the
positive experiences obtained in the conservation of lighthouses worldwide. This project was
commissioned, according to the instructions of Plovput’s General Manager, Ante Čulić, and
Neven Šerić and Hrvoje Mandekić with the close cooperation of other Plovput employees
from the firm carried it out. The Project aimed to find an acceptable way to ensure re-payment
of the loans obtained for the repair, maintenance expenses and other accompanying costs for
the upkeep of the lighthouses. The surplus would be re-invested so that in the future all the
forty lighthouses along the Croatian coast of the Adriatic Sea could be revitalized and newly
equipped and additional funds for the permanent maintenance of the lighthouses would be
ensured.
The second, vital feature of the Stone Lights Project is reflected in a sustainable model of
establishing rules of conduct for the guests in tourist suites in the lighthouses. This segment of
the Project emphasizes the importance of the high ecological standards which must be
respected.
In addition to the exploitation of renewable alternative energy sources – sun and wind, the
proposed standards for the disposal of waste water and solid wastes are also very high.
Thanks to such environmental requirements this Project has been approved by the Croatian
Ministry of Environmental Protection and Physical Planning which gave it a special award in
the Tourism and the Environment category in 2001.1
1.2. The Problem of Waste Water Disposal from the Lighthouses
The lighthouses, without regard to their original function or the restricted number of tourists,
or scientific expeditions on research projects, are specific facilities considering the disposal of
waste water. Since some are located quite far off-shore or in the projecting capes of the
Adriatic coastal belt, they are in an environment sensitive to pollutants. It has been estiamted
that 150 litres of waste water daily per person is average.2
Years ago there were direct collectors taking the waste water to the sea. It should be noted
that 50 years ago there were sometimes 20 residents at some lighthouses which is not the case
today although the lighthouses will be used for tourism.3
1
2
On the date of World Environmental Protection Day each year this Ministry gives special awards in different categories.
The Sušac pilot project carried out in cooperation with Polytecnic School, Split, included the analysis of man’s influence
upon the flora and fauna on the island, the organization of man’s life on a remote isalnd and the disposal of waste water and
solid wastes. Ref. Experience on Sušac, summer 1999, the Split Polytechnics, 1999. Non-published paper.
3
Lighthouses intended for tourism generally include suites for four to eight persons.
2
In spite of some suggestions4 that the waste water should be treated only mechanically, i.e.
that the removed suspended matter is ground and released with waste water into the sea, the
solution proposed by this Project is quite different. It is based on the experience in the U.S.A.
where a biological treatment model was long ago adopted because it has been proved that
suspended matter causes changes on the sea bed and on flaura and fauna below the sea
surface.
The Adriatic Sea is characterized by weak sea currents since it is a closed sea. The local
currents between the islands change intensity and occasionally completely disappear. Due to
these facts, the ending sections of the submarine outfalls can rarely be laid so that the waste
water is released directly into the flow of the main current. Hence, due to the estimated
quantity of waste water, placement of the submarine collectors below the allowed depth, has
been deemed unacceptable, since the pollution point would be moved further from the shore
and would not yield an adequate solution. The waste water released by the submarine outfall
rises to the surface. Along that line, from the outfall to the sea-surface, it quickly mixes with
the sea causing turbulence. If the sea depth at that position is not adequate the water reaching
the suface is significantly diluted and, later can be even more diluted by surface dispersion
processes until it finally disappears in the sea.
Considerations about improving the initial dilution by the best selection of the release location
and the use of a diffusor do not ensure, in our opinion, the solution of the problem, since the
subsequent dilution depends upon natural conditions which cannot be influenced. The
computation of the initial and subsequent dilution can be obtained by employing
mathematical models5 which can be used as guidelines in the outfall design. However, there
are a great number of factors along the coast of the Adriatic Sea which change from one
location to another, at small distances, so that the obtained mathematical solutions represent
only more or less precise approximations deviating from the real conditions. The location
point which can satisfy the proposed ecological criteria can be determined only by an
experienced designer. The investigations and practical tests are crucial and should be carried
out for each lighthouse.
The computation of acceptable quantities of waste water released into the sea should also
meet the requirements for the treatment and decomposition of the treated sludge, since
uncontrolled decomposition can bring about significant changes in the structure of the flora
and fauna at a specific outfall location. All the presented viewpoints and experience seem to
stress the primary importance of the elements of the system of waste water disposal plants
located on the coast, in the vicinity of the lighthouses.
4
Such practical models can be found in England, the Netherlands and Denmark. However, in those cases the submarine
outfalls are several chilometers long and located at ocean shores where the currents are strong and permanent.
5
Ref: P.E. Gaynor & R.C. Kirckpartick, Introduction to time-series modeling and focecasting in business and economics,
Mc Graw-Hill Inc. New York 1994.
3
2. INFILTRATION WELLS AND THEIR INTRODUCTION INTO THE WASTE
WATER DISPOSAL SYSTEM AT THE LIGHTHOUSES
As noted in the previous section, the search for an optimal solution of waste water disposal at
the lighthouses has centered on the systems removal from the outfall to the coast, in the
vicinity of the lighhouses. Since the Project includes the tourism it is important to determine
whether or not there is a real danger of infection and diseases caused by contact with the
diluted waste water. An accurate answer can be given only after extensive epidemiological
investigations carried out in the vicinity of urban areas along the Adriatic coastline. The
results of the performed investigations do not exclude the possibility of disease; however, a
significant correlation between the intensity of seawater pollution and the incidence of
diseases among the toursists6 has not been proved. The seawater pollution is determined
according to the bacteria from the digestive tract of mammals, continuously present in the
faecal water. Pathogenic agents do not exist unless there are cases of disease among the
population or persons carrying those viruses. The frequency of disease incidence among
tourists also depends upon their immunological properties. Let us go back to the priority
stated in this paper, i.e. the search for an optimal model for a total waste water disposal
system at the lighthouses. In this actual project the authors do not support any of the two
extreme positions, i.e. 1. ignoring the threat from pollution and sea contamination, or 2.
radical activities which cannot be effected and which cannot be justified from the economic,
technical or sanitary standpoint.
It has been proved that infiltration wells are the most acceptable solution and that their
introduction into the waste water disposal system significantly reduces the quantiy of waste
water and sludge in the submarine outfalls. The design based on the required capacity and
the number of these infiltration wells at a specific location takes the following factors: 1. the
number of persons in the lighthouse, 2. the type of collectors delivering the water from the
system of infiltration wells into the sea, 3. data on the frequency and direction of sea currents
and 4. specific features of the flora and fauna in the submarine microlocation.
Approaching the problem in this way several models of infiltration wells have been designed
and some of them are presented in the Appendix.
2.1. Results of the expoitation of infiltration wells in the disposal of waste water from the
lighthouses
The analyses carried out in situ have shown that the total results of the use of infiltration wells
for the disposal of waste water from the lighthouses have been better than expected. This can
be accounted for by the significant influence of the average temperatures which together with
high-quality dilution agents contributed to a faster decomposition of waste water while it was
retained in the trenches. Furthermore, we believe that the psychological effect of making the
tourists familiar with the operation of these complex systems for the preservation of the
required ecological standards, has resulted in the reduced consumption of sanitary water.
The contribution of these infiltration wells is also evident in settlement processes and
decomposition of sludge so that these processes do not occur on the sea bed.
The projects of infiltration wells are in the initial phase since different models represent a
challenge both for the engineering profession and for all those concerned about the
environmental aspects of future projects.
3.
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CONCLUSION
Ref: Dr. Ivo Eterović, I., Environmental protection, Proceedings, The Municipality of Split, 1983, p 70-72.
4
In accordance with the Land Based Sources Protocol, LBS Athens 1980, and the 1995.7
programme for monitoring the disposal of both domestic and industrial waste water into the
Croatian Adriatic Sea and the pollution input through steamflows and canals, Plovput Ltd. has
attempted to show, by introducing infiltration wells the system of waste water disposal from
the lighthouses, that each segment of this complex problem requires a specific approach and
sometimes even the disputed model Bottom Up8 can lead to an optimal model by creating a
strategy through practical methods.
Further development of the full potential of the Adriatic region can be ensured only by
bearing in mind the fact that Croatia is a maritime country and that the respective
consequences result from this fact. Plovput believes that much can be done in this direction by
employing its own resources and in cooperation with other reseach institutions in Croatia and
other Mediterranean countries. Further implementation of a complex investment project such
as Stone Lights9 requires future scientific planning of all activities and especially those related
to environmental concerns which can otherwise have hazardous effects in the future.
The main objective of such planning is either to achieve a solution or at least to attempt to
solve the complexity of the co-existence between man and environment, particularly in the
specific areas of remote small islands and capes along the Adriatic coastal belt where the
lighthouses are located. Further development of the Project, which stresses that it is necessary
to educate each tourist who stays at one of the lighthouses, can lead to improved
environmental consciousness about the significance of the continuous search for innovative
solutions for improving the marine environment.
These stone lights, the lighthouses, today shine with a light that will be intensified at new
locations along the Adriatic coast and off-shore; they will be there for future generations
telling them stories about the past life on the lighthouses and will serve as a sustainable
model for Croatian tourism. These buildings will remain as cultural monuments reminding all
of ancient times when the lights were manually lit and seawater pollution was not a problem.
The use of the infiltration wells in the disposal of waste water from the lighthouses represents
a small step towards preserving this natural environment for the future.
REFERENCES
7
Ref. The Government of the Republic of Croatia, National Authorities for Envrionmental Protection, Republic of Croatia,
Zagreb 1998.
8
Ref. Al Ries and Jack Trout: Bottom – up marketing, Mc Graw-Hill, Inc. New York 1989. P 61.64.
9
N. Šerić., Conceptual premises and constraint variables in the implementation of a complex investment project Stone
Lights, University of Split, Faculty of Economics, Split 2001, unpublished paper.
5
1. Eterović, I., Environmental protection, Proceedings, The Municipality of Split, 1983, p
70-72.
2.
3.
4.
5.
Gaynor P.e. & Kiorckpatric R.C., Introduction to time-series modeling and forecasting in business and
economics, Mc. Graw-Hill Inc. New york 1994.
Al Ries and Jack Trout: Bottom – up marketing, Mc Graw-Hill, Inc. New York 1989. P 61.64.
Šerić N., Conceptual premises and constraint variables in the implementation of a complex investment
project Stone Lights, University of Split, Faculty of Economics, Split 2001, unpublished paper.
The government of the Republic of Croatia: national institution for the environmental protection, report on
the state of the environment in the Republic of Croatia, National institution for the environmental protection,
Zagreb, 1998.
ZBRINJAVANJE OTPADNIH VODA U EKOLOŠKI OSJETLJIVOM OKRUŽENJU
POMORSKIH SVJETIONIKA
Sažetak: Projektom revitalizacije napuštenih svjetioničarskih zgrada poduzeće Plovput d.o.o.
iz Splita posebno se pozabavilo modelima rješavanja otpadnih voda na svjetionicima.
Analizirajući svjetska iskustva i prilagođavajući ista specifičnim uvjetima Jadrana, zatvoreno
more sa slabim i nejednolikim morskim strujama, u ovom projektu pristupilo se izgradnji
upojnih jama u sklopu sistema zbrinjavanja otpadnih voda. Modeli upojnih jama
dimenzionirani su oblikom i kapacitetom ovisno o geomorfologiji tla pojedine lokacije,
proračunatoj dnevnoj količini otpadnih voda, te karakteristikama morskog dna, morskih
struja i vjetrova na konkretnoj lokaciji pojedinog pomorskog svjetionika. Rješavanju svih
problema u području ekologije mora potrebno je pristupiti kroz konkretne slučajeve.
Uopćenih, tipskih rješenja nema. To je i osnovna svrha ovoga rada, koji ukazuje na način
pristupanja problematici iz ove domene kroz jedan konkretan primjer.
Ključne riječi: svjetionici,revitalizacija, otpadne vode, zbrinjavanje, upojne jame.
6