ferns paradiserw hproposal

BIOME ENVIRONMENTAL SOLUTIONS PVT. LTD._______________________________________________

Rainwater Harvesting at the Ferns Paradise LayoutRAINWATER HARVESTING AT THE COLLECTIVE LEVEL

(Roads and Common areas)Overall Rainwater Harvesting Plan Report

____________________________________________________________________________No 1022, VI Block, H.M.T. Layout, Vidyaranyapura, Bangalore – 560097.

Phone: 080-41672790, 080-23644690Email: [email protected] Website: www.biome-solutions.com


Rainwater Harvesting in Ferns ParadiseOverall Rainwater Harvesting Plan Report

TABLE OF CONTENTS

1 Customer Details .......................................................................................................................................... 3 1.1 Contact Info ............................................................................................................................................ 3 1.2 A Brief Overview ................................................................................................................................... 3 1.3 Expected and Actual Water Demand/Supply ......................................................................................... 3

2 Rainwater harvesting at Ferns Paradise ......................................................................................................... 3 2.1 Overall runoff and potential for recharge at Ferns Paradise ................................................................... 4 2.2 RWH at the Collective level (primarily storm water drains) .................................................................. 5 2.3 Recharge Rate Testing Strategy .............................................................................................................. 6 2.4 Locating Recharge Wells ........................................................................................................................ 6 2.5 Recharge Well Design ............................................................................................................................ 9

2.5.1 Recharge Well – Off drain ............................................................................................................... 9 2.5.2 Recharge Well – In Drain .............................................................................................................. 10

2.6 Drain management ................................................................................................................................ 11 2.6.1 Silt traps ......................................................................................................................................... 11 2.6.2 Upstream In-Drain Filter/Check Dam ........................................................................................... 11

2.7 Monitoring Recharge Well Effectiveness in the long terms ................................................................. 12 2.8 Contour trenching on Vacant Plots ....................................................................................................... 13 2.9 Water management consultation ........................................................................................................... 13

2.9.1 Arriving at a fair pricing scheme ................................................................................................... 14 2.10 Next Steps and Consultancy Charges ................................................................................................. 15

3 APPENDIX .................................................................................................................................................. 18




1 Customer Details

1.1 Contact InfoName and Address of Customer Ferns Paradise, Doddanekundi

Off Outer Ring RoadBangalore

Customer Type LayoutContact Person name Ms BabitaContact Phone number – Land line -Contact Phone number – Mobile 9845076731Email id [email protected]

[email protected]@[email protected]@yahoo.com

Date of Visit 23rd Oct 2009Date of Report 6th Nov 2009

1.2 A Brief OverviewFerns Paradise is a layout spread over an 43 acres and has about 300 plots in Phase 1 and 2. About 85 homes are currently occupied. There is no Cauvery water connection and all water on campus is pumped from borewells within the campus. Water from these borewells is pumped to 1 sump/overhead tank. From here water is provided to all the households. Water consumption at household level is metered. There is 1 STP on campus. Currently STP treated water is not being used for any purpose. The overall attempt is to ensure sustainability in water. Rainwater harvesting is an important step in that direction.

1.3 Expected and Actual Water Demand/SupplyThe actual demand for water in the layout is about 100KL per day. Assuming that all plots (about 300) are lived in and about 5 members per household a demand of 300KL per day (assuming 200 litres per person per day, as opposed to standards of 135 Litres per person per day) can be expected. This translates to an annual demand of 109,500KL (300KL * 365)

2 Rainwater harvesting at Ferns ParadiseThe overall strategies for RWH at Ferns Paradise can be the following, as detailed below:a. Rainwater harvesting for common buildings like the club house (This is not

being explored at this time since Clubhouse is owned by the builder)b. Rainwater harvesting for individual households (This has not been covered in

the proposal)c. Rainwater harvesting for common areas(roads, parks), especially by

diverting water from storm water drains. (This is covered in the remaining part of this document)

This document details harvesting of rainwater from the storm water drains.



mailto:[email protected]





2.1 Overall runoff and potential for recharge at Ferns Paradise

Total area: 43 acres = 137,593 square metres

Hence the total annual rainfall on the entire catchment is of the magnitude of 170844KL (which is GREATER than the expected annual requirement of Ferns Paradise even at full occupancy). The below table represent the total runoff that is available for harvesting after assuming losses due to run-off co-efficient, evaporation, soil moisture etc.

Land use Area(sqm)

Annual run off – 970mm(KL = 1000 litres)

Run-off for average rain (30 mm) (KL)

Run-off for heavy rain (60 mm) – KL

TOTAL – 43 acres 176128 170844 5284 10568Plots (inclusive of rooftop and landscaped areas)(coeff of runoff– 0.7)

123664 83968 2597 5194

Roads (coeff of runoff– 0.7)* Pl. see the associated spreadsheet for details of length/area of roads

39343 26714 826 1652

Open spaces (coeff of runoff– 0.4)

13121 5091 157 315

It can be seen from the above table that maximum run-off is from plots and then from the roads / paved areas. This means that both to avoid flooding and capture maximum run-off water for rainwater harvesting, the areas with the built up area and the roads need to be first addressed.

Even if we were to assume that all homes implement RWH and hence there is no runoff from the rooftop that enters the storm water drains, there is about 983KL (826+157KL) of water to be harvested even after an average rainfall of 30mm from common areas. This roughly translates to about:

245 wells of 3ft dia and 20 feet deep (4 KL capacity)OR61 wells of 5ft dia and 30 feet deep (16 KL capacity)

The assumption that no recharge happens during the falling of the entire 30mm of rain has been made while computing the number of wells required.




Based the assumption of more or less uniform distribution of roads/open areas and homes in the entire layout, and a realistic number of 100 wells in the open drains it can be said that for every 200 feet of untapped storm water drain (based on estimated 10505 of roads and 21010 ft of storm water drains on either sides of the road), a well of 3ft dia and 20ft deep can be located. Given reasonable recharge rates and assuming that the wells would recharge an effective volume of 30 times its capacity (120KL for each well), annually about 120,000KL of water will be sent into the ground for recharge which would offset the annual demand at full occupancy.

2.2 RWH at the Collective level (primarily storm water drains)

Water harvesting at the collective level can and should be driven through storm water drains as they are the arteries of Storm water in the layout. They play the role of conveying storm water out of the layout. Therefore they become the logical points from which storm water can be sourced for harvesting. Typically due to quality issues, the water from storm water drains are used for recharge and the recharge well (refer also APPENDIX) can be used as a very effective recharge structure in Bangalore. Our experience suggests that Individual household rooftop water is best for storing (at the household tank level) and common area run-off is effectively used for recharge thus helping borewells of the layout. RWH also helps managing storm water and avoiding floods. Hence digging of open wells located at strategic points along the storm water drains is proposed for ground water recharge. Recharge wells need to be atleast 20 feet in depth. They can vary in diameter and depth (3 to 6 feet in dia, 20 to 30 feet in depth) depending on the quantum of water.

Since in this layout the water is transported through HUME pipes, chambers have already been provided at regular intervals. It is proposed that these chambers be used as locations for the filters. Spots close to the chambers would need to be identified for the construction of the recharge wells

The estimated cost of the recharge wells (please note that this is an estimate and not a quotation) is as follows:Item Cost Estimate Well capacity3 feet dia, 20 feet deep recharge well Rs 22,000/- 4KL5 feet dia, 30 feet deep recharge well Rs 65,000/- 16KL

Silt traps, check dams, in-drain filters and reconstruction of the drains for the breakages that will be incurred during the well digging will work out to about Rs 10,000 to Rs 15,000 per well. The costs for the recharge wells can be lowered if suitable dumping ground for the excavated earth can be found within the Ferns Paradise premises

• The above are estimates not a quotation.• Upon acceptance of this proposal, the proposed contractor will provide an

accurate quotation for the above




2.3 Recharge Rate Testing StrategySince the strategy for Ferns Paradise focuses primarily on ground water recharge, the testing of recharge rates in various parts of the campus is fairly important. So as to do this information was collected from individual residents to study the recharge rates in their existing structures. Based on the inputs from the well owners one can fairly say that the percolation rates in the area are good and recharge would be a sound strategy to deploy.

Once the initial wells have been dug, Biome will conduct a slug test on each of the wells, which involves filling the wells to capacity with water from a tanker, and then monitoring the rate at which the water percolates into the ground. One reason behind recommending 10 recharge wells in the pilot phase is to test the recharge rates in different areas, as soil conditions can vary even within a 43-acre radius. This too can be done in a Phased manner

This test is critical for gauging the actual effectiveness of groundwater recharge in the area. If percolation rates are found to be very low due to high rock or clay concentration, then recharge becomes a less attractive option for widespread application and Biome will alter its RWH accordingly.

2.4 Locating Recharge Wells

50 good locations for well have been identified in the subsequent map. Out of these the best 10 wells (to allow for maximum recharge) as well as to test for the nature of soil across the campus have been detailed here. The wells have been selected based on

1) Availability of a large quantum of water (from a large catchment) has been the primary basis for location of wells




2) Wells have also been located close to existing borewells since it has been observed that the proximity of recharge wells to borewells does increase borewell yield.

3) Wells have been located in various parts of the campus so that the observed recharge rates from these wells can serve as a basis for the location of the subsequent wells

4) In front of currently vacant plots (this can be taken into consideration while finally locating the wells)

The wells have been marked as

Well No

Size(ft) Location and Remarks

1 5(dia)30(deep) Near Borewell 1, space is available for a large well

2 5(dia)30(deep) In the main street in front of the club house, proximity to borewell 7

3 3(dia)20(deep) West on 10th Street to test for recharge rates in the western side of the campus

4 3(dia)20(deep) 8th Street near borewell 65 5(dia)30(deep) North on 1st Cross. To test for

recharge rates on the farther part of the campus

6 3(dia)20(deep) On 2nd Cross near plot 8887 3(dia)20(deep) On 2nd Street near plot 623 for

recharge of borewell 78 3(dia)20(deep) On first street near plot 6009 3(dia)20(deep) Upstream of borewell 3 on 3rd Street 10 3(dia)20(deep) In the park for recharge of borewell 8

Note− The roads that have not been named have been considered as Cross roads

and have been numbered sequentially.




2.5 Recharge Well DesignBased on space constraints as well as certain other factors recharge wells can either be placed in the storm water drain or off the storm water drain. This section details both designs2.5.1 Recharge Well – Off drainHere the recharge well is located at some distance from the storm water drain




2.5.2 Recharge Well – In Drain

Here the recharge well is located inside the storm water drain




2.6 Drain management

So as to ensure good recharge, the storm water drains have to be managed such that large and expected quantums of water actually make their way into the well. As far as possible the drain should be kept clear of construction debris and other obstacles. Check dams/Upstream in-drain filter upstream of the recharge well function as filters and keep out contaminants from entering the recharge well. A small obstruction a little downstream from the inlet to the recharge well needs to be created to obstruct the water from flowing further downstream and entering the recharge

well. Silt traps prevent silt from entering the recharge well and hence protect the recharge well from silting up and reduced recharge rates

2.6.1 Silt trapsA silt trap is a structure that is created in the storm water drain but whose depth is greater than that of the storm water drain. This provides the storm water a receptacle in which to stay for some time. During this period the silt settles down and leaves the water on top fairly silt free. This water then proceeds into the recharge well. Soak away pipes are provided at the bottom of the silt traps to ensure that water doesn’t remain in the silt trap after the rains thereby becoming a breeding ground for mosquitoes etc. In this case Silt traps are not

recommended since it was found that the drains carry fairly clean water.

2.6.2 Upstream In-Drain Filter/Check Dam

Based on their location these check dams serve two purposes. In one case they serve as an intake for the recharge well and redirect the water into the recharge




well. They can also be located upstream of the recharge well and here they serve as filters.

2.7 Monitoring Recharge Well Effectiveness in the long terms

Another critical component of a sustainable water management regime is infrastructure management, and especially the supply infrastructure, which in this case is Ferns Paradise’s community and private borewells. Critical questions must be addressed pertaining to the longevity of the borewells given their current extraction rates, the maximum number of borewells the layout can sustain given its hydrogeological situation, and how likely it is that recharged water will feed the aquifers supplying the borewells.

The answers to these questions will have significant management implications, which could call for restrictions on private borewell digging, restructuring of water pricing schemes, and perhaps increased or modified groundwater recharge plans. The investigation needed to answer these questions may warrant a special hydrogeological study.

It is important to put in place a monitoring strategy to monitor the effectiveness of the recharge strategy that is put in place. Ground water recharge through recharge wells has been observed to increase the local ground water table, increase borewell yield and improve the quality of water from the deep aquifers (borewells). The following is suggested to monitor the same

Improvement in water quality : It has been observed that with continuous ground water recharge the water that is got from borewells progressively turns softer. This would require that water from each of the borewells be tested and regular records of the reports be maintained (on an annual basis)

Improvement in water discharge:




Ground water recharge also progressively increases the yield from the borewells. So as to monitor this a mechanism of borewell metering needs to be put in place. Meter readings would need to be systematically taken, maintained and analysed.

Biome’s recommendation is to start with borewell meters. The cost for the borewell meter and its installation, along with the creation of a masonry chamber that facilitates the taking of borewell meter readings, is approximately Rs. 20,000 per borewell, though the implementation fees would be reduced if all borewells were taken care of at once.

Current Borewell Inventory

Borewell No

Location Yield information

1 2nd Street, Between plots 814 and 816

Good yield

2 2nd Street, Between plots 635 and 637

Dry. Inside a house/plot

3 3rd Street,Near plot 649 Not sure if this is a borewell

4 5th Street, Near plot 685 Uneven flow, yield not known

5 6th Street, Near plot 695 Average Yield

6 7th Street, Between plots 719 and 721 Average Yield

7 On the main road, near the park in front of plot 621

900' deep, Good yield

8 Inside the park Good yield

2.8 Contour trenching on Vacant PlotsContiguous plots in Phase 2 were found to be empty. Namely plots 801-807 and plots 816-821 etc. If permission is obtained from the plot owners simple contour trenches could also be built on this land. These could be manually dug – about 1ft deep. The excavated earth should be placed on the lower slope of the trench. This would serve as locations for mulching and would improve the soil quality as well as allow for retention of water on the land

2.9 Water management consultation

Perhaps the greatest step that Ferns Paradise can take toward safeguarding its long-term water security is to manage the demand from its water resources in a responsible manner that achieves efficiencies without reducing standard of living. The most important intervention in this regard is to introduce a fair pricing scheme for household water consumption. Other critical interventions related to borewell management ought to be considered as well. The following describes how Biome proposes to engage with the Plot Owners Association to develop a water management regime that prioritises conservation.




2.9.1 Arriving at a fair pricing scheme

The fairest and most effective system of water pricing is the progressive block tariff that ensures a low-cost supply of lifeline water to all homes, and gradually increases the cost as consumption surpasses certain pre-determined levels. Setting prices and consumption levels that effectively managing demand and are acceptable to the residents is a requires a feedback process to make any necessary adjustments. Before the feedback process even begins, however, a basis for determining appropriate pricing must be established. The most sensible basis for water pricing is the production cost of water, which focuses on recovering the true cost of delivering water to the home.

Finding the production cost of water

Biome will anchor an exercise to calculate the water supply cost, which includes reviews of past bills and projections of future expenses for electricity consumed for borewell pumping, maintenance and replacement costs for water infrastructure (replacing valves and borewell pumps, cleaning the water towers, etc), staff time and expense, regular water testing, and any treatment applied before it reaches the home. These costs will be factored against the total water supplied to determine the production cost per kilolitre.

Ultimately, for this system to work, both the supply of water (borewells) and the demand for that water (households) would be metered, as that will identify if there are any major leakages in water delivery infrastructure and will be required if households are to be billed based on their own consumption levels.

Biome’s recommendation is to start with borewell meters. The cost for the borewell meter and its installation, along with the creation of a masonry chamber that facilitates the taking of borewell meter readings, is approximately Rs. 20,000 per borewell, though the implementation fees would be reduced if all borewells were taken care of at once. Household water meters have already been installed in Ferns paradise and this is a very good first step in this direction

Setting new pricing slabs

Once the production cost per kilolitre is known, the new pricing slabs reflecting that cost will be created. Biome will work with the FPPOA to set the proposed new pricing slabs. The key criteria for setting the prices are the following:

• They reflect the production cost of supplying water to the residents.• They reflect people’s right to a lifeline supply of water to meet the

household’s basic needs.




• They penalize wasteful use of water so as to encourage conservation.• They acknowledge that good water practices (such as household RWH)

need to be rewarded.

Work with FPPOA to engage with residents

Once the new slabs have been agreed upon by the POA, its next job is to communicate the new scheme and its rationale to the residents. This process requires equal measures of openness, patience and tact, as it will likely require time to convince some residents of the necessity to pay for their water. Biome will help the POA develop circulars announcing the newly proposed scheme, and will help the POA create platforms for holding dialogue about the proposed scheme.

Work with staff to facilitate new scheme implementation

Biome will review the implications of the new pricing scheme for the roles of staff members, and train them accordingly. If requested, Biome will also develop measures for staff performance vis-a-vis their new responsibilities.

* The consulting fee for the same has not been included in the commercials

2.10 Next Steps and Consultancy Charges

A phased approach is suggested for the implementation of the proposal

Phase Schedule (from project approval date

Activities Reasons

Pilot phase: Phase 0

Within 3 months • Digging of 10 wells (1-10) as identified in the map

• Testing of recharge rates and identification of well locations for Phase 1

Primarily for testing of recharge rates in various parts of the campus

Phase 1 Within 4th to 12th

month• Digging of 10 wells

(well 11-20)• Observation of

wells during the rainy season

To increase recharge capacity

Phase 2 Within 1st year and 2nd year

• Digging of 20 wells (well 21 to 40)





Phase Schedule (from project approval date

Activities Reasons

• To set in place the framework as well as for monitoring of effectiveness of recharge wells on borewells

Phase 3 3rd to 5th year • Completion of 100 wells


The key next steps for the pilot phase would be :

a) A detailed design phase for the locating and designing of 10 recharge wells and corresponding designs and locations of check-dams and silt traps , detailed estimation of costs and submission of quotation by implementing contractor.

b) Implementation of the Rainwater harvesting system.c) Testing for recharge rates from these 10 wells and identification of locations

for the next 10 wells for Phase 1

Biome will participate in the next steps in two possible ways :Option I : Consultancy for detailed design and supervisory services during implementation. In this option the Client can choose his/her own contractor. However, it is important that Biome works with the contractor during the detailed design phase. Implementation quotations will be separately submitted by the chosen contractor.Option II : Consultancy for detailed design and supervisory services during implementation. In this option Biome will bring in an appropriate partner contractor for the implementation of the works. Implementation quotations will be separately submitted by the chosen partner contractor.




The consultancy charges for the above options for the Pilot phase – for 10 recharge wells is as mentioned below :Service AmountSite visit and Submission of Overall Rainwater harvesting plan (This report – Invoice enclosed)50% has already been paid

Rs 8000.00

Option I :- Consultancy during detailed design (will

include submission of detailed design drawings)

- Supervisory services during implementation- Testing of wells for recharge rates and

identification of locations for Phase 1 wells

Rs 25,000

Option II- Consultancy during detailed design (will

include submission of detailed design drawings)

- Bringing in partner contractor for implementation

- Supervisory services during implementation- Testing of wells for recharge rates and

identification of locations for Phase 1 wells

Rs 30,000

Total Option I Rs 8000.00 + Rs 25,000.00Total Option II Rs 8000.00 + Rs 30,000.00

Notes:• Service Taxes if applicable will be charged extra at around 10.3 %.• A payment schedule can be discussed on acceptance of this proposal.• All payments to be made by cheque to the name of “Biome Environmental

Solutions Pvt. Ltd.”, A/c payee crossed.




3 APPENDIX

The following are details about the rainfall pattern in Bangalore and drive design:Parameter MeasureTotal Annual average rainfall 970 mmTotal no of rainy days 60 rainy daysPeak hour intensity of rain in Bangalore 60 mm/hr

The rainfall distribution pattern in Bangalore is as follows :MONTH DAYS QUANTITY (mm)

JAN 0.2 2.70FEB 0.5 7.20MAR 0.4 4.40APR 3.0 46.30MAY 7.0 119.60JUN 6.4 80.80JUL 8.3 110.20AUG 10.0 137.00SEP 9.3 194.80OCT 9.0 180.40NOV 4.0 64.50DEC 1.7 22.10

TOTAL 59.8 970.00It can be observed from the above table that Bangalore is blessed with a relatively well distributed rainfall and has a rainfall distribution which is bi-modal (two peak rainfall seasons in a year). In this context, and given Bangalore’s geology, rainwater harvesting strategies appropriate for Bangalore has been found to be the following in their respective order of priority.

a) Storage of rainwater for direct use : Priority is given to capture as much of the run-off rainwater in storages such as sumps, on-ground tanks or tanks on terraces at intermediate levels (eg: sitouts / balconies). However for such a strategy, the run-off only from clean areas can be tapped. It is important that these catchment areas be free from any form of chemical or other toxic contamination and dust content is as low as possible. Typically roof areas qualify well for such a strategy. The water from this run-off is first rain separated, filtered and then let into the storage. The water can be used for all household purposes such as bathing, washing, cleaning, gardening etc directly and can even be used for potable purposes if subsequently it is passed through filters to deal with bacterialogical contamination (Eg: aquaguard filters, boiling etc). However, this requires that roof areas be kept clean and there is no junking of material on the roof or movement of pets such as dogs and cats on the roof and there is no soap water washing of the roof area. In apartments these forms of contamination are often observed in private terraces. A water testing process prior to use for drinking and cooking purposes is recommended. Subsequently regular potability tests are also recommended.




b) Groundwater recharge : Excess run-off from above mentioned clean surfaces, run-off from other surfaces such as roads, garden area etc can then be redirected for groundwater recharge. In the context of Bangalore, the most effective recharge structure has been found to be a recharge well whose depth is a minimum of around 15 - 20 feet. These recharge wells recharge the shallow aquifer. Water needs to be desilted adequately before allowing the water into recharge wells. The location of the recharge wells need to be chosen strategically – both where significant run-off water passes through the recharge well location and which is close to existing ground water sources of water. Recharge wells, over time will help replenish groundwater. If the ground water table rises above the bottom of the recharge well, the recharge well can be used as a withdrawal well. Recharge wells are likely to help recharge local borewell sources of water though such guarantees cannot be provided. The diagram below illustrates the principle of recharge.



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