Coastal Environment Quality Management
The Digha-Sankarpur area is one of the busy tourism areas of the state. The tourism is generally heavy (except during the monsoon months) and particularly so during the holiday seasons/periods and on week ends. Day trippers are also frequent in this coastal area. Since 2004 DSDA is the nodal agency for looking after the planning and development in the Digha-Sankarpur planning area, which is spread over an area of 8752.63 acres. It has 42 nos. Mouzas and is partly covered by three nos. of Gram Panchayets namely Padima-I, Padima-II, Talgachari-II. The total population is 50,000 (approx.).
There is no functional underground sewerage and drainage system with house connections and treatment facilities. Solid waste collection and sanitary disposal system are almost absent. Day trippers pollute the area indiscriminately due to inadequate civic facilities. Therefore a separate component encompassing-
Beach area at Digha is getting constantly polluted due to presence of large number of vendors operating from unauthorized shanties constructed on sea front. The items of transactions particularly food items prepared and sold by the vendors are source of pollution mainly as organic waste. The fishermen undertaking fishing operation at sea shore are also responsible for polluting the beach by dumping dead fishes and also other living organism. The day trippers visiting the area leave trashes and litters during their stay at the beach area. As a result, the beach area is getting vitiated by the unwanted dumpings. The system of collection of refuge by the DSDA is very weak resulting in beach area remaining dirty. Moreover, due to inadequate presence of amenities like toilets and change room with shower facilities the day trippers visiting the beach area are inconvenienced forcing them to pollute the areas by using those as open toilets. The problem is not so acute at Sankarpur as no shanties have grown up in the beach area owing to lesser number of tourists visiting Sankarpur as the beach area is threatened by menacing beach erosion. Beach cleaning and sanitation is considered most important for maintaining a clean environment for attracting more tourists to Digha. A number of strategies have been evolved to make the beach area clean and improve its sanitation.
The strategies proposed are given below:
i) Beach cleaning
ii) Pay & use toilets along with changing rooms with shower facilities
iii) Pay and use toilets without shower facilities
iv) Removal of unauthorised shops/structures closest to the beach area and introducing rehabilitation scheme for such shop-owners.
Sea beach cleaning involves the removal of materials left by the tides on Digha shorelines. Stranded seaweed provides an important food source for beach food chain and should be left in place where possible. Human debris can pose a hazard to humans and animals, and should be removed. The use of machanised beach cleaning equipment may cause serious disturbances to the bio-diversity in sea beach and shorelines. Though sea turtles are not found in Digha sea beach, but plenty of crabs could be seen along the beach.
Digha sea beach is approximately 5000 metre length. Around 2300 metres of the sea beach is packed with concrete block and boulders. This stretch of the beach covers Old Digha fully and New Digha partly. The beach cleaning operation in this stretch needs to be carried out manually. It will be difficult to operate mechanical cleaners along this specified stretch. The remaining approximately 2700 metre stretch of sea beach is concrete free and boulder free. The sea beach varies between 40 metres and 50 metres during non-tidal period.
The Digha sea beach is not presently cleaned regularly. Tourists pollute the sea beach by throwing solid waste indiscriminately. This includes good quantum of plastic materials. The plastic materials (especially tea cups) go into sea during tide. The plastic cups could be seen inside the sea when these get arrested in the fishing nets. A few stalls, mainly selling tea and snacks, could be seen in the sea beach.
The beach cleaning operation will be carried out as suggested below:
- Litter bins will be installed at places where crowding occurs by the tourists (50 nos. @ 100 meters interval);
- Manual cleaning by hand picking and sweeping is recommended in sea beach covered with concrete steps and boulders (5 nos. of sweepers);
- Manual cleaning by hand picking and sweeping is also recommended in the sea beach in rest of the stretches (5 nos. of sweepers);
- Hand operated mechanical beach cleaner (1 no.) is recommended for the use;
- Motorised vehicle for cleaning of sea beach through hand picking (1 no.).
i. Pay & Use Toilet along with Shower Facilities
Creation of pay and use toilet-cum-change room with shower facility has been considered essential to maintain a clean and hygienic environment within the area. In addition, this has been considered as one of the most important basic amenities for the tourists during their stay at Digha. The establishment of these facilities spatially distributed within the town will go a long way in mitigating the vital deficiency of infrastructure to promote the designed tourism for Digha. In all 9 (nine) such facilities have been proposed within the area. Keeping an eye to economy in cost and space, a standard module has been developed to be repeated within the area. The development plan takes care of the separate provisions for the exclusive use of males and females for toilet, bathing and drinking water facility. The toilets, bath-cum-change room facilities, sanitary conveniences have been designed on a certain rational presumption regarding the dispersion of the tourist population in the area.
The water supply, drainage and sanitation required for the above facility have been designed on the assumption that 30 % of tourist population estimated for a design period of 30 years onwards of 2009 ( peak seasonal weekends) will use the amenities created. In determining the above requirements, two minimum standards indicated in Indian Standard Code for basic requirement for Water Supply, Drainage and Sanitation, one for Domestic Airports and the other for Bus stands, Railway Station ( Intermediate) and Seaports have been considered.
The development planning consists of integrating the two separate blocks for ladies and gents with a common waiting lobby, ensuring complete privacy for the ladies toilet. The space planning has been evolved to accommodate the required number of W.Cs, urinals, bath-cum-change rooms, washbasins and drinking water facility for both male and female. The space planning for water closets, urinals, bath-cum-change rooms and washbasins with their inter-linkage with the waiting lobby have been made to offer easy and convenient movement of the users. The drinking water facility, which is a free service, has been provided within the waiting hall for common use of both male and female. The building has been conceived to have pitch roofing with provision of false ceiling to provide a decent interior look. The ceiling height at eaves level from the floor has been fixed at 3500 mm. with large number of doors and windows as required ensuring natural ventilation, day light, thermal comfort and easy access for the tourists. Due care has been given to the selection of locations of such blocks so that the conveniences can be used easily by the users for which they are meant. With a sufficiently high plinth level – 900 mm. from the access road and the surrounding area being covered with abundant tree plantation, the toilet and bath-cum-change room facility will offer a most hygienic and green environment to its users.
As regards internal electrification, concealed wiring with energy efficient luminaries for providing proper level of illumination in W.C.s, change rooms and waiting lobby and electric fans in waiting lobby as required for displacement of air have been proposed. The main power distribution board of the building will receive power from WBSEDCL from its nearest transformer. The technical specifications of civil structures have been given in the DPR.
ii. Pay & Use Toilet without Shower Facility
Pay and use toilets in the areas away from the beach have been planned to maintain a clean and hygienic environment within the townships. The development plan takes care of the separate provisions for the exclusive use of males and females for toilet and drinking water facilities. The W.C., urinal and other sanitary conveniences have been designed on a certain rational presumption regarding the probable number of users. The development planning consists of integrating the two separate blocks for ladies and gents with a common waiting lobby, ensuring complete privacy for the ladies toilet. The space planning has been evolved to accommodate the required number of W.C.s, urinals, washbasins and drinking water facility for both male and female. The space planning for water closets, urinals, and washbasins with their interlinkage with the waiting lobby have been made to offer easy and convenient movement of the users. The drinking water facility, which is a free service, has been provided within the waiting hall for common use of both male and female. The building has been conceived to have pitch roofing with provision of false ceiling to provide a decent interior look. The ceiling height at eaves level from the floor has been fixed at 3500 mm. with large number of doors and windows as required ensuring natural ventilation, day light, thermal comfort and easy access for the tourists. Due care has been given to the selection of locations of such blocks so that the conveniences can be used easily by the users for which they are meant. With a sufficiently high plinth level – 900 mm. from the access road and the surrounding area being covered with abundant tree plantation, the toilet facility will offer a most hygienic and green environment to its users. As regards internal electrification, concealed wiring with energy efficient luminaries for providing proper level of illumination in W.C.s, change rooms and waiting lobby and electric fans in waiting lobby as required for displacement of air have been proposed. The main power distribution board of the building will receive power from WBSEDCL from its nearest transformer. The technical specifications are given in the DPR.
Phytoremediation is the use of living green plants for in situ risk reduction and/or removal of contaminants in soil and water. The present proposal intends to build a Bioremediation STP which is to be located behind Aparajita cottage. Bioremediation STP will significantly reduce Biochemical Oxygen Demand (BOD) load and also stabilizing the DO (Dissolved Oxygen) to a certain extent. BOD is a measure of the content of biologically degradable substances in sewage. The septic water from the surface drain will be made to flow in a number of channels properly designed with implementation of specific variety of plants to interact with pollutants and thereby to reduce the toxicity and make the water suitable for discharging into the sea with BOD5 concentration less than 30ppm.
There are 1485 number of unauthorized shops dealing with local crafts, food items (fish, cashew etc.).These shops are presently situated along the cross roads joining the Fore Shore road and Embankment. The majority of the shops have come into existence near the Blue View Ghat at Old Digha and Kshanika Ghat at New Digha. These shops have been built up in haphazard manner causing nuisance to the area along the crossroads by dumped garbage and creating interference with the easy movement in the area. To get rid of the unsightly situation, it has been decided to shift the shops to Vendors’ Rehabilitation Centers at three sites identified by DSDA. The 3 sites identified for rehabilitation are planned to accommodate as many as 620 shops among the 1485 shops during the project phase. The rehabilitation shops have internal dimension of about 3.0 M. X 2.5 M. The plan form of the rehabilitation center has been developed to house the individual shops in multiple rows with common passages in between the rows. The planning takes into account the requirement of free movement of the people inside the complex for transacting the wares and of finding easy access from all sides by means of plenty of entry and exit points. Sufficient ventilation and natural lighting have been ensured for providing comfort both to the purchasers and vendors.
The building will have ceiling height of 3.5 M. from the plinth level covered with temporary roofing made of tubular trusses covered with GCI sheet membrane. A pitch roof of single span truss has been proposed for convenient disposal of rainwater falling on the roof membrane. Provision of covered drain running along the passage has been made to dispose of the rainwater coming from the roof. A false ceiling has been proposed to offer an aesthetically pleasing view to the visitors. Each rehabilitation center will have access from all abutting roads and will be enclosed with a decorated brick built boundary wall to ensure a pleasing and secured environment. Landscape elements along with illuminations have been provided within the 3 sites as much as possible to enhance the beauty and aesthetics of the centers. The entire sites will be covered with interlocking paver tiles for easy movement of pedestrians. As regards internal electrification, concealed wiring with energy efficient luminaries to provide proper level of illumination in shops and passages, and electric fans in shops as required for displacement of air have been proposed. The main power distribution board of the complex will receive power from nearest WBSEDCL transformer. The technical specifications are given in the DPR. The component will be implemented by DSDA.
The work elements to arrive at cost estimates are as follows:
- Dismantling of shanties (unauthorised stalls) and construction of temporary sheds for rehabilitation
- Rehabilitation Centre - 1
- Rehabilitation Centre - 2
- Rehabilitation Centre - 3
- Land levelling for Rehabilitation Centres
- Paved area for all Rehabilitation Centres
- Pump room
- Semi-underground water reservoir for all Rehabilitation Centre
- Elevated RCC platform
- Distribution pipelines network
- Pay and Use toilets with shower facilities (9 nos)
- Pay and Use toilets without shower facilities (2 nos)
- Constant beach cleaning
Sanitary sewage treatment scheme is a long perceived need in Digha. There is no centralized sewerage system in the region and stand-alone systems (septic tank with soak pit) do not work very well in this region owing to high water table. Being a tourist area (with about 300 hotels), sewer load generated in this region is high and fluctuating. Well planned centralized sewerage system is one of the major building blocks for implementation of Integrated Coastal Zone Management Plan in the region.
The first plan of sewage treatment scheme was prepared by Planning Circle I, PHE at an estimated cost of Rs.244.27 lakhs. This was revised again in 1996 to bring some additional areas under the purview of the scheme with an estimated cost of Rs.409 lakhs. The scheme was taken up for execution in 1997. After a portion of sewer line was laid, work was suspended due to sand boiling at 1.45m (R.L.). This necessitated further review of the scheme. Revised scheme was prepared again with due consideration to the following points.
- to restrict sand boiling problem during laying of sewer line.
- ground water infiltration @ 5000 litres / hectare / day.
- the rate of per capita water supply at 125 litres / day.
Based on the re-design, the suspended work was resumed in 2000 and laying of 6496 metres of different diameter sewer line and 1248 metre of different diameter pumping main. One main pumping station and 4 sewage lifting stations were also constructed within the sanctioned of Rs 409.00 lakhs against the estimated re-designed cost of Rs 457.41 lakhs. Work has remained suspended since then due to lack of fund.
The suspended sanitary sewerage scheme of Digha area has now been re-designed considering a design period up to 2025 and additionally including Udaypur area of New Digha and is proposed to be taken up as a component of the SPR of West Bengal.
The design parameters of the scheme are as follows:
|Design population in 2025||
Anticipated floating tourist in 2025
Per capita sewage flow
100 lpd (assuming per capita water supply as 125 litres / day and spend water flow as 80%)
Ground water infiltration for a command area of 300 hectares
Total sewage generation
Existing length of sewer line
Proposed length of sewer line
Diameter range of sewer line
150 mm to 600 mm
Existing length pumping main
Proposed length pumping main
Existing sewage lifting stations
Proposed sewage lifting stations
Existing sewage pumping stations
Proposed sewage pumping stations
Capacity of sewage treatment plant
Process of sewage treatment
Waste Water Pond
The methodology of treatment proposed is Waste Water Pond (WSP) comprising anaerobic, facultative and maturation ponds. The top dimension including free board of the anaerobic (4 nos), facultative (8 nos) and maturation ponds (24 nos) will be 53 m x 30m x 3.5 m, 88 m x 44 m x 2 m and 45 m x 17.7 m x 2 m respectively.
The total time required for execution of the proposed component is three years including time required for tendering, vendor selection and six months of trial run. The total estimated cost of the renovation work of Digha sanitary sewage scheme is Rs 3559.23 lakhs (project cost to be financed is Rs 3424.50 lakhs) comprising costs related to civil works as well as mechanical/electrical works . The cost also includes charges for service connection as well as cost of trial run and guarantee for initial three years of operation and maintenance by the agency (Rs 180.00 lakhs) executing the entire work on turn-key basis. Monitoring and evaluation cost has not been given separately in DPR. The scheme will be implemented by the Public Health Engineering Directorate of Government of West Bengal.
Although Digha town was established long time back, no worthwhile solid waste management system has been in place resulting in unscientific deposal of refuge and thereby environmental pollution goes unabated. A pilot scheme was initiated sometime back to take care of bio-degradable wastes, applying process of vermicomposting. The said scheme at present is lying non-functional. Sankarpur is comparatively a new area emerging as a tourists’ destination. Sankarpur suffers from total absence of any solid waste management to handle the daily refuge generated by tourists as well as by the local residents. As a result, the beach area is getting continuously polluted. In order to address the problem confronted both at Digha and Sankarpur, a solid waste management system has been planned to be commissioned for both the areas. The system of solid waste management for both the towns will be created in the same manner.
The proposed management system consists of primary sorting of the solid waste at the points of generation, collection and transportation of sorted refuge, putting the biodegradable materials into process of vermicomposting, recycling of the non biodegradable but reusable refuge components and finally disposal of non biodegradable remnants through engineered sanitary land filling system. Towards sanitary land filling, one suitable site common to both Digha and Sankarpur has been identified. The proposed site for solid waste disposal at Padima mouza of Digha lies beyond the Coastal Regulation Zone within land ward side. Therefore, no CRZ compliance is necessary.
The primary segregation of waste at sources will be undertaken in dwelling houses, hotels and commercial establishment in three categories namely, organic waste, inorganic non recyclable waste and inorganic recyclable wastes by depositing each category of waste in different colour identified containers. Similarly, waste generated in community use will be collected in separate bins meant for organic waste and inorganic waste. The street waste will also be collected in community bins .The segregated wastes will be collected and transported in containers by pedal tricycles to primary transfer stations (PTS) to be located in nine places for which the Digha town will be divided into nine segments. The wastes from the containers of each tricycle will be transferred to bigger containers at PTS whence the wastes will be transported by prime movers to the disposal ground. The solid wastes on reaching the disposal ground will be finally treated for safe disposal in the following three processes :
ii) Secured Land Filling
The organic solid will be put to composting by two different process viz. vermicomposting (50% of organic waste) and windrow composting (50% of organic waste) under one composting shed. The recyclable non-organic will be disposed of through agency to be selected. The inorganic non-recyclable waste will be treated by engineered secured land filling.
The container for storage of solid waste will be made of plastic with lid and handle. The pedal tricycle will have a capacity to accommodate 6 nos of 50 litres containers that will also be made of plastic with lid and handle. The community bin may be constructed of masonary with tile finish outside having a size of 1200 mm x 900 mm x 800 mm with 2 flap doors and two flap shutters. Litter bins (50 nos) will be made of fibre glass attached to concrete posts. The PTS will be of masonary construction with provision of ramps for movement of pedal tricycles. It will have unloading quay.
The vermiculture unit will require spraying of water regularly. It will be kept under shed for protection from sunlight. Initial decomposed organic waste will be placed over vermiculture unit. The windrow composting will have marked bay where the day’s organic waste will be placed in rows. Water will be sprayed to have 50% moisture. On every sixth day the waste row will be tilted upside down for proper mixing. The organic waste will be converted to compost in 21 days. 15 days maturation period is required before use. Secured landfilling will be engineered operation with earth cover and compaction. The landfill will have a final cover of 30 mm earth and landscaped top.
The design of solid waste management system for the town Digha has been done with the following considerations:-
- Primary Storage, Primary Collection and Transportation
Design Year : Present - 2009; Future - 2016
- Secondary Transportation
Design Year : Present - 2009; Future - 2016
- Treatment and Disposal
Design Year : 2039 (30 years design period)
The current (2009) generation of solid in Digha is given below:
- Weekends (non-seasonal) – 11.44 MT
- Weekends (seasonal) - 14.04 MT
- Weekends/holidays (seasonal-peak) – 15.67 MT
There is an increase of 2% per year.
The total container requirement (2009) has been estimated as follows:
Number of Green Bin (organic waste) of 5 litres capacity: 3718
Number of Black Bin (inorganic non-recyclables) of 5 litres capacity: 3718;
Number of (35 cm X 25 cm size) Bag (inorganic recyclables): 3380
Number of Green Bin (organic waste) of 15 litres capacity: 1359
Number of Black Bin (inorganic non-recyclables) of 15 litres capacity: 1359
Community bins are to be provided at suitable locations. Each community bin will have provision for storage of organic and inorganic solid waste. Mostly, the street food vendors will deposit solid waste in the community bins. The street sweeps will be also deposited in the community bins
Street sweeping services are to be provided in the areas where tourists move These areas are mostly on the southern side of Foreshore Road, between sea guard wall and Foreshore Road. Street sweeping services are also necessary in market places and congested localities of the other southern side of Foreshore Road. Pedal tricycles fitted with containers will be used for collection and transportations of street sweepings. The size of each community bin is 1200 mm X 900 m X 800 mm. Each community bin will be divided in to two equal parts to store organic and inorganic waste separately.
The total number community bins required are
Old Digha: 6 Nos.
New Digha: 8 Nos.
Litter bins are to be placed in suitable locations, especially where tourists move around. It is suggested to provide 50 nos. bins of capacity 10 litres each.
Solid waste from all sources initially will be collected and transported by pedal tricycles. The pedal tricycle will contain 6 nos. of 50 litres containers. The total number of pedal tricycle required for collection of solid wastes from all sources has been estimated at 54.
Primary Transfer Stations (PTS)
The town is to be divided in 9 segments. Each segment will have one Primary Transfer Station (PTS) as designed. The solid waste will be collected from all sources by pedal tricycles and the waste will be transferred to bigger containers at PTS. The PTS will be comprised of ramp road with elevated platform for unloading solid wastes from pedal tricycles to bigger containers which will be taken thereafter by prime movers to the disposal ground. Total number of PTS = 9; Area requirement for each PTS =150 sq. m.
The solid waste will be transported to treatment and disposal sites from nine specified PTSs. The secondary transportation system will comprise of tractor and hydraulic lifting arrangement for container attachment to tractor. There are different standard sizes of containers with hydraulic lifting arrangement. As per field survey of Digha, it is recommended to use 3.5 m3 containers. The total no. of tractor required is 4 and the total number of trailor containers required is 16.
The solid waste will be disposed by the following methods:
b) Secured land filling;
It is proposed to carry out composting of organic solid waste by the following two processes:-
a) Vermicomposting (50% of organic waste);
b) Windrow composting (50% of organic waste).
The total area required for vermiculture unit has been estimated at 675 m2.
The total area required for windrow unit inclusive of maturation pond and screening and packaging has been estimated at 1356 m2.
The non biodegradable, non recyclable and inert wastes will be disposed off as sanitary land filling. The total land requirement for SLF inclusive area for office building (60 m2) and plantation area (800 m2) will be about 42389 sq.m. A land measuring 5.99 hectares belonging to Digha-Sankarpur Development Authority (DSDA) is available at Padima Mouza for treatment and disposal of solid waste. The land is accessible by road. The land is low-lying in nature. The land is suitable for treatment and disposal of solid waste.
The methodology of solid waste management at Sankarpur will be same as that of Digha. The target and principle of solid waste management in Sankarpur accordingly will also be same as that of Digha. The expected solid waste generation (2009) will be 2.30 Mt, 2.82 MT and 3.14 MT during weekends (non-seasonal), weekends (seasonal) and weekends/holidays (seasonal-peak) respectively.
The requirement of household containers will be
Green, 5 litres capacity = 1355;
Black, 5 litres capacity = 1355;
Inorganic recyclables = 1200
The other requirements are
Community bins = 10
Litter bins – 10 litres capacity = 35;
Pedal tricycle = 17 (9 pedal tricycles for house to house collection+6 pedal tricycles for street sweeping+2 pedal tricycles as standby);
Primary transfer stations = 6 (area will be divided in 6 segments);
Tractors = 2 (including 1 as standby);
Tractor containers = 10 (6 trailors for 6 zones, 2 for 2 tractors and 2 as standby)
As there no space available for treatment of solid waste at Sankarpur, the entire seggregated waste will be transported to the Digha facilities for treatment and disposal.
The estimated work components are as follows:
- Sanitary landfill area development at Digha
- Vermi-composting sheds at Digha
- Office building for vermin-composting sheds at Digha
- Concrete yard for wind row at Digha
- Internal surface drains and site development works
- Internal roads
- Primary and secondary collection equipment for Digha and Sankar pur separately
Total estimated cost of implementation is Rs 922.50 lakhs.
Absence of a properly implemented drainage system is causing adverse effect on the hygienic condition in the town of Digha. The drains are too few and were constructed mainly to flush out excess water during high tides. More importantly, the drains also are carrying sullage water and the polluted water is discharged into the sea causing appreciable deterioration in the quality of sea water. It is a fact that the area lying near the sea coast is mainly of silty sand allowing high rate of percolation of surface run off to ground for which widespread water logging is not in evidence in the area till now, yet with the town getting more populated day by day, incidence of tourists’ visit looking up along with hotels and institutional buildings getting concentrated in localized area, the need for commissioning an engineered drainage system has been badly felt to discharge the water efficiently into the sea without causing any harmful effect on the environment. Such a drainage system will exclude any chance of water logging and at the same time will offer a clean and pleasant look for the town. Open surface drains, to be built with brick masonry, have been designed and planned for implementation at Digha only to collect the surface run off and carry the water at a non-silting velocity by gravity flow. Sankarpur, being sparsely populated and having a very few hotels /lodges all surrounded by vast expanse of agricultural lands, has been left out of such drainage facility at present. Construction of storm water drains is an allowed item under CRZ regulation, since it is of the white water quality and mostly the high water during spring tides coming inside the coastal area will be discharged through the storm water drains into the sea.
The existing surface drain passing by the side of beach embankment at Digha meant for carrying storm water is charged with sullage water and effluents of septic tanks. The water carried by the drains is thus highly contaminated with organic wastes and becomes septic with high concentration of BOD5. This septic water gets discharged into the sea in violation of environmental safety. An attempt has been made to clean the water by effectively reducing the BOD5 content by subjecting the urban liquid waste to the process of environmental-friendly, cheap but widely accepted process of phyto-remediation. In fact, phyto-remediation was adopted as a pilot project at Digha to clean the water at a very low cost, which produced a satisfactory result in increasing the dissolved oxygen so long as the project at Digha was under operation. Later on due to lack of proper monitoring, the process failed to achieve the desired result and at present is lying non-functional. It is now proposed in this project to reintroduce the process of cleaning the water through phyto-remediation at Digha on a much wider scale. A stretch of area measuring 300 meter by 50 meter along the beach has been selected and reserved for phyto-remediation. The septic water from the surface drain will be made to flow in a number of channels properly designed with implantation of specific variety of plants to interact with pollutants and thereby to reduce the toxicity and make the water suitable for discharging into the sea with BOD5 concentration less than 30 ppm. Sankarpur has been left out of the system of phyto-remediation for the present on the grounds mentioned earlier. Discharge of treated waste and effluent into the sea is an allowed item under Section-2 (v) of CRZ Notification, 1991.
There is practically no planned drainage net work in Digha area. In some parts there are road side open drains but it is very inadequate. A combined drainage sewerage system exists in some stretches. The existing drains are insufficient to convey storm water during monsoon. The existing drainage system, therefore, needs immediate upgradation and improvement. Accordingly, it has been proposed to lay surface drainage system for Digha area under DSDA. The drainage system will have several outfalls leading directly and indirectly to the Bay of Bengal and to the Canal besides Digha Bypass. The existing kachha drains will be lined.
The technical specifications are as follows:
- Type of drain – Brick built open type surface drain
- Base of drain – PCC 100mm thick to be laid on 1 layer of brick flat soling
- Side walls – Brick masonry wall varying in thickness from 250 mm to 750 mm to be constructed with burnt bricks having crushing strength 75 kg./cm2 , bonded with sand cement mortar in 6:1 proportion
- Finishing – The external surface and the top surface of the drain section will be finished with 20mm thick sand cement plaster in 1:4 proportion to be rendered with 1.6mm thick cement punning.
So far the attempts to bring the entire city sewage of Digha Township under a STP have not met with success due to level difficulties arising out of older dunes on which a major portion of the Old Digha town had developed. During 2007-08 an attempt was made for a pilot Bioremediation STP behind the Aparajita Cottages which was quite successful in reducing the BOD load and the outfall DO attained a concentration of 6.5 mg./l.
Two numbers of aeration ditches in series will be created to have sufficient capacity to retain liquid wastes for 3 days with a buffer of 1 day. The outflow from the ditches will be made to pass in 4 furrows intercepted by mangroveOne Storm W root zones which will act to reduce the septicity of water to the tolerance limit, through root zone absorption.
The technical specifications as worked out are given below:
- Aeration ditches – 2 each of 3000 m3 capacity
- Residence time – 3 days plus 1 day buffer
- Ridges and furrows – 4 each 0.9 m deep and 20 m long
- Clearing period – every 2 months
- Plants to be provided
Aeration pond – water hyacinth or duckweed
Furrows – acanthus ilicifolius and sonneratia caseolaris
Ridges – minjiri (cassia siamea), eucalyptus
The cost estimates are as follows:
Rs in Lakhs
1. Construction of storm water drains
2. Construction of phyto-remediation of urban sewage system
Total (excluding cost towards electrical works, goods & equipment, operation & maintenance and monitoring & evaluation)
The proposed Green Building at Hospital Complex to be constructed by PHED will serve multiple purposes. It will have allotted room spaces for discharging administrative duties and responsibilities, laboratory, staff quarters, rest shed, stores, etc. An internal pathway along with street lighting and fences embedded with bushes and shrubberies surrounding the building will be put together. As ICZM Project is an environmental project the proposed building will be based on LEED green building rating system. The target is to achieve Platinum certification provided by LEED rating system. A building with Platinum certification means it has taken care of the sustainability issues by recognizing the performance in five key areas of human and environmental health:
· sustainable site development
· water efficiency
· energy efficiency
· materials selection
· indoor environmental quality