Rainwater harvesting methods and water catchment methods are another component of One Community’s open source project-launch blueprinting strategy for building a global collaboration of self-sufficient and self-sustainable teacher/demonstration communities, villages, and cities for the Highest Good of All. Rainwater catchment and harvesting will be incorporated into all seven different village models, the Duplicable City Center Hub, our sustainable food systems, and even our sustainable energy infrastructure. This page will function as the portal and hub for all of our water research, development, and ongoing open source project-launch blueprinting of duplicable rainwater harvesting methods, water catchment techniques, and swale building strategies.
We discuss this and more with the following sections:
NOTE: THIS PAGE IS NOT CONSIDERED BY US TO BE A COMPLETE AND USABLE TUTORIAL UNTIL
WE HAVE OUR PLANS PERMITTED AS PART OF THE CONSTRUCTION OF THE EARTHBAG VILLAGE.
AT THAT TIME WE WILL ADD HERE THOSE PERMITTED PLANS AND ANYTHING ELSE WE LEARNED.
IN THE MEANTIME, WE WELCOME YOUR INPUT AND FEEDBACK
Rainwater catchment, rainwater harvesting, and rainwater collection are all names for the collection and storage or rainwater. With proper filtration, this rainwater can be used for drinking and cooking. With minimal filtration it can be used for bathing, clothes washing, and dish washing. With no filtration it can be used for watering gardens and houseplants, flushing toilets, washing cars and buildings, composting, outdoor ponds and water features, fire control, etc.
The benefits of harvesting rainwater are many and we’d like to help more people experience these benefits. Collecting and using rainwater reduces municipal water needs and peak demands (demands on ground water), reduces costs/water bills, and is good for the environment. Proper harvesting also reduces flooding and erosion.
Open sourcing the rainwater catchment specifics for all seven different village models, the Duplicable City Center Hub, and our sustainable food systems is primarily for replication. It is also to help with open source collaborative improvement of the designs, as an example of the process and needs for other similar-sized structures, and to share here additional specifics like purchasing and installation details, the maintenance and upkeep process, etc.
SUGGESTIONS ● CONSULTING ● MEMBERSHIP ● OTHER OPTIONS
Charles Gooley: Web Designer
Daniela Andrea Parada: Civil Engineering Student
Julia Meaney: Web and Content Reviewer and Editor
Matheus Manfredini: Civil Engineering Student specializing in Urban Design
As we continue open source project-launch blueprinting our water harvesting and catchment systems, build them, and problem solve and evolve them for One Community (and with others around the world) we will develop this page as the portal detailing open source and free-shared specifics related to this component including:
Water catchment will be a part of every structure we build and the list above will evolve into links with the related details on each individual structure page so we can organize, evolve, and share the details that people need to duplicate every aspect of this component of One Community in part or in whole.
Water catchment will be a part of every structure we build and the list above will evolve into links with the related details on each individual structure page so we can organize, evolve, and share the details that people need to duplicate every aspect of this component of One Community in part or in whole. Through our catchment strategies, One Community is confident that we can create an environment where we are capable of harvesting and storing more water than we use for daily living through this and other water conservation and catchment methods. This page explores this with the following sections:ugh a combination of water conservation and catchment methods. This page shares the following details:
As part of our commitment to Stewardship and Highest Good Living, the Pioneer Team will work to demonstrate maximum water efficiency and conservation. Below are some examples of what current average (A) versus conservative (C) water use looks like through conscientious practices applied to everything from taking a shower to reusing a drinking glass:
Looking at these numbers the average American uses around 50 gallons of water a day versus a more conservative approach only using 15-20 gallons! With a desire to demonstrate what is possible we are seeking maximally efficient appliances and designing warm and comfortable shower spaces to make practices like starting and stopping a shower to soap easy to do. We are also planning a separate “non-washing” hot waterfall experience (like a hot tub shower) for the ultimate experience of just standing in a huge volume of hot water and letting it run as long as a person likes without wasting any water.
Combining the calculations above we calculate a liberal 20 gallons of use per person X 365 days in the year = 7,300 gallons of water used per person each year. 339,892 gallons (see below) harvested off the earthbag village/7,300 gallons per person equals enough water for 46 people. Adding the water catchment from the Duplicable City Center City Hub (99,240 gallons), our sustainable food systems (136,555 gallons), and our solar panel array catchment (46,058 gallons) would provide enough water for an additional 40 people for a total of 86.
We are exploring additional water conservation approaches in an attempt to achieve 100% water self-sufficiency for all residents plus the additional 30% population of less conservation-minded visitors we will be hosting. All water not produced this way will be provided from on-site wells.
The earthbag village (Pod 1) is the first village model we will be building and the water catchment for the entire village has been calculated using the following color coordinated zones: yellow for domes, pink for patios, blue for roads & walkways, and orange for the Tropical Atrium.
Rainwater catchment for the dome homes would entail aggregating a gutter to each structure. Utilizing a gutter would create potential complications with the water, such as freezing. To avoid these obstacles, the domes are not designed to harvest water. Overall there are 82 domes with an external diameter of 18 feet and 4 domes with an external diameter of 28 feet.
Water catchment off the patio and stair areas (pink) of the dome clusters and has been calculated as follows:
The surface area of all the patios (pink) therefore equals (10 x 675) sq. feet + (6 x 269) sq. ft. = 8,364 sq. ft. Using a (conservative for our location) 10-inch annual rainfall* and applying the formula for calculating water harvesting (catchment area x rainfall x runoff) yields: (8,364) X (.833) X (7.48) = 52,115 gallons of water harvested per year from the patios and stairways.
Water catchment off the primary roadway and walkways (blue) and has been calculated as follows:
The total surface area of all the roadways and walkways (blue) is 34,882 sq. feet. Using a (conservative for our location) 10-inch annual rainfall* and applying the formula for calculating water harvesting (catchment area x rainfall x runoff) yields: (34,882) X (.833) X (7.48) = 217,344 gallons of water harvested per year from the patios and stairways.
Water catchment off the Tropical Atrium and surrounding walkway has been calculated as follows:
The total surface area of the Tropical Atrium (orange) is therefore 11,304 sq. feet. Using a (conservative for our location) 10-inch annual rainfall* and applying the formula for calculating water harvesting (catchment area x rainfall x runoff) yields: (11,304) X (.833) X (7.48) = 70,433 gallons of water harvested per year from the patios and stairways.
*Note: For calculating cistern and pond sizes we used the average annual rainfall for our location of 13.6 ~ 15 in = average of 368.3 mm. For calculating pipe size we used the Daily Critical Rainfall (the maximum daily amount of rainfall in our location) of 1.3″ / 33 mm.
Here are the details of the water collection and transport system.
To determine the pipe sizes we needed:
To minimize the costs with excavations and soil removal, the slope of piping needs to be as minimal as possible without creating a potential water backup. The table at right shows the international standard for the minimum slope for each size of the pipe.
For most of the plumbing area we are using 2.5″ pipes, which ensure us with a 1/4″ slope. The radius of our village is ~170 feet minus 9 feet because our drainage won’t start right in the middle of the village. This gives us a drop of 41 inches for the international standard slope equal to 1/4″/foot associated with a 2.5″ pipe.
To calculate the discharge rate on each drain we need to know the catchment area (a) for each drain, the daily critical rainfall (b) and the coefficient of absorption of the soil (c).
Taking a critical storm that could last 1.5 hours, the maximum hourly amount can be rated as 1,500 gallons for each hour.
Looking at drains 9 and 10 (see below) as the 2 drains that receive the most amount of water, the estimated combined catchment area is ~2,500 square feet. This is lower than the safe drainage amount estimated for any one drain. This means we have an adequate safety factor.
Taking PVC as the material of the pipe, the roughness coefficient is 150.
The stormwater harvesting system is designed to collect runoff water on the ground surface. Compared to the rooftop rainwater harvesting system that has a relatively limited catchment area, a much larger catchment area is applicable to this system. The stormwater is usually collected for end uses such as toilet flushing and irrigation. The design of the stormwater harvesting system is similar to the design of the rooftop rainwater harvesting system which also calls for the calculation of the catchment area and the storage capacity with consideration of the supply and demand of water. However, the much higher flow rate, lower water quality, and larger storage capacity of the stormwater harvesting system requires higher water conveyance capacity, larger pre-filtration facilities, and more expensive storage containers.
We discuss the design and implementation of this system with the following sections.
In this project, we use the monthly rainfall of a particular area to determine the rainfall supply. Most local monthly rainfall data can be found online by searching a target location’s name followed by ‘Climate Normals’. The collected local monthly rainfall data for high desert Utah is prepared in a sheet format as shown below. We use a metric unit to illustrate the method.
Local monthly rain data is then used to calculate the total annual average rainfall and averaged monthly rainfall. The total annual average rainfall is the summation of the monthly rainfall of twelve months. The averaged monthly rainfall is equal to the total annual average rainfall divided by twelve.
When calculating the water supply, runoff efficiency must be taken into consideration. Depending on the porosity and absorption of a roof’s material there can be losses in the amount of rainfall that gets collected. A table of runoff efficiency based on the types of area surface and material is shown below.
For non-homogeneous areas, a weighted runoff coefficient should be computed, such that
where
In this case, we assume the runoff coefficient is equal to 0.9. The input in the calculation table is shown below.
The effective rainfall takes into consideration losses during catchment and therefore, it is what is used to calculate the final volume of water that can be effectively stored in the water tank. It is equal to the actual rainfall multiplied by the roof efficiency.
The table below shows the results of the total annual average rainfall, the total annual rainfall supply, the averaged monthly rainfall, and the averaged monthly rainfall supply.
The yearly rainfall supply can be calculated with the following formula:
Yearly rainfall supply = Total annual average rainfall x Catchment area x Roof efficiency
Based on this formula, we can estimate the catchment area as long as we determine the needed yearly rainfall supply. We want the annual rainfall supply to match annual water demand in order to ensure a sufficient amount of water is harvested for use. In the next section we are going to determine the water demand.
Water demand is dependent upon the number of occupants, the water consumption of the fixtures, and the usage patterns of fixtures. In this project, we assume that one installment of the rooftop rainfall harvesting system supplies 100 occupants.
The potential fixtures using the harvested water include toilets, showers, and faucets. In this case, we assume the toilets are the only fixture that is supplied by the harvested stormwater. The average manufacturing rating and usage pattern of different fixtures are shown in the following table, where Lpf is liters per fixture; Lpm is liters per minute; and Lpd is liters per day.
As stated previously, only usage of Toilet-1 is considered in this case. From the water demand of all fixtures per person per day, we can deduce the total daily demand of all occupants, monthly water demand of all occupants, and yearly water demand of all occupants. The results are shown in the following table.
A catchment area is an area of land where rainwater flows into a specific water body such as a lake, river, or ocean. The size and shape of the catchment area determines how much water will be collected and the rate at which it will flow into the water body.
We want the yearly rainfall supply to match the yearly water demand such that,
Yearly rainfall supply = Yearly water demand,
This is ideal in the instance that only the minimum yearly supply is needed without redundancy. Combining the formula introduced in the section of rainfall supply, we derive the formula for the catchment area such that,
Catchment area = Yearly water demand / total annual average rainfall x roof coefficient.
The results of the rooftop catchment area are shown below.
The catchment area of stormwater harvesting is about 16,000 ft^{2}.
For buildings and facilities, the basic requirements are: all portions of the facility, and all points on the exterior wall of the first story of a building, must be within 150 feet of a fire apparatus access road.
A water tank size being equivalent to the yearly rainfall supply guarantees a sufficient water storage capacity. However, this method would result in an impractically large water tank. Determining the optimal storage capacity design happens through multiple trial and error processes and can not be found simply with one single input and output process. The water tank should be large enough to ensure that it never reaches a zero volume. In our case, we want to find a minimum storage capacity to prevent zero volume storage at the end of each month based on the monthly rainfall supply and the monthly water demand.
Firstly, we assume a storage capacity such that:
This input of assumed storage capacity needs to be adjusted to balance the supply and demand of the stormwater harvesting system. By adjusting assumed storage capacity, we aim to ensure all the month end volumes from years 1 to 4 in the “Storage Performance” are larger than zero. The first attempt of the assumed storage capacity could be the summation of the largest three demand months. The largest three demand months are found in the “Demand” column of the table below.
Then, check if any Month End Volume is equal to zero in the Years 1 through 4 columns of the table.
Keep reiterating the previous procedures until an absolute minimum is found that balances the supply and demand of the rainwater harvesting system.
As the table shows, the estimated storage capacity is 18,756 gallons. Accordingly, we take 20,000 gallons as our design stormwater storage capacity. The estimated stormwater storage tank is 70,000 inches^{2}. The 20,000 gallons is equivalent to 462,0000 inches^{3}. Given this, the estimated height of the stormwater storage tank is 66 inches.
Considering the standard length, width, and height of a single atlantis flo-tank block:
Height = 450 mm = 17.716 inch
Width = 408 mm = 16.063 inch
Length = 685 mm = 26.969 inch
In order to meet our storage capacity demands, we take the 4 flo-tanks with a total height 70.864 inches, 13 flo-tanks with a total width 208.819 inches, and 13 flo-tanks with a total length of 350.597 inches. Each flo-tank has a 31.56 gallon storage capacity and thus, 676 flo-tanks are needed. When placed together in the area we have for digging, these combined tanks create a cuboid shape. Therefore, the total storage capacity ends up being 21,334.56 gallons, which is larger than the estimated needed storage capacity of 20,000 gallons. Accordingly, this redundancy is acceptable.
The price of a Quad Flo-Tank is $132. To meet our storage needs of 21,335 gallons, we’d need 169 quad flo-tanks, which would cost $22,325. Compared to a traditional 10,000-gallon tank (which costs $22,500 each) the quad flo-tanks option is half the cost.
The rational method is the most widely used method for estimation of the rainfall peak discharge, which can be defined as the maximum flow rate of a certain area during the rainfall. The rational method is usually limited to areas below 1 square mile (640 acres). The rational method is a formula such that,
Q_{p} = CIA_{C}
where
To calculate the inlets peak flow discharges, which is the maximum discharge flow rate of the inlet area, we need to determine the catchment areas and inlets locations. The goal of calculating inlet peak flow rate is to determine pipe size. With knowing the slopes of conveyance pipes of each section, we can size pipes based on the international plumbing code. The diameter of pipes is expected to increase from upstream to downstream.
Using a CAD drawing is an effective way to obtain the area of each catchment section and to visualize the locations of the inlets with their corresponding catchment areas. A labeled engineering drawing of the stormwater harvesting catchment sections and inlets is shown below. The inputs of the following calculation table are rainfall intensity, catchment areas of each section, runoff coefficient, and slope. The inlets peak flow discharges is a summation of the flow rate of its corresponding catchment sections and the flow rate water from upstream.
Our net-zero bathroom stormwater storage design is a sustainable approach to water management that aims to collect, store, and reuse stormwater in residential or commercial bathrooms. The system involves using a series of filtration and storage tanks to capture and treat stormwater, which can then be used for toilet flushing, washing, and other non-potable water needs. The goal of the design is to achieve a net-zero water balance, where the amount of water used in the bathroom is equal to the amount of stormwater collected and reused. This approach helps to conserve water resources, reduce the strain on municipal water supplies, and minimize the environmental impact of wastewater discharge. The design process involves analyzing factors such as water demand, stormwater availability, and site conditions to determine the optimal system size and configuration.
We discuss the design and implementation of the net-zero bathroom stormwater storage system with the following sections.
*Note: This content can also be found as part of the Water Recycling Net-zero Bathroom page due to its relevance to the Net-Zero Bathroom design.
Storage containers for the stormwater harvesting system usually require much larger capacities compared to those of the rooftop rainwater harvesting system. Limited space and irregular geometry of facilities on the ground may not allow for a large capacity water tank. Accordingly, belowground water tanks could be an appropriate solution. Belowground water storage systems save land space, protect water from cold weather, are almost limitless in size, and are utilized in most commercial projects. However, belowground water storage systems need excavations. In this section we will discuss the different components of our belowground stormwater storage system.
There are three main types of tank that are considered for stormwater storage: fiberglass cistern tank, Atlantis Flo-Tank and reinforced concrete water tank.
Fiberglass cistern tanks could be of good use for stormwater harvesting and storage. Considering manufacturing, transportation, and cost, the accessibility of fiberglass cisterns is limited. A 10,000 gallon fiberglass cistern tank costs around $22,000, which is very expensive, and lasts around 30 to 40 years. However, less construction is needed for fiberglass cisterns in comparison to other options. The following figure shows two fiberglass cisterns which together offer a total of 20,000 gallons of storage capacity. They are placed in the center, surrounded by the net-zero bathrooms and the shower rooms.
An Atlantis Flo-Tank system is a cheaper and more flexible water storage solution that is utilized in many commercial stormwater harvesting projects. The water containers consist of small water tank blocks where each block is built with pieces of plastic boards. The size of the container is not limited and the lifespan is an estimated 100+ years. Also, there is no concern for the difficulty of transportation. A 10,000 gallon Atlantis Flo-Tank system costs about $10,000, which is about half of the cost of the fiberglass cistern tank. An Atlantis Flo-Tank water storage system would also be placed in the center of the earthbag village.
A reinforced concrete water tank (RCC) is a traditional type of water tank that is built on-site. This tank only calls for common construction materials. Cracks, which is a usual failure type of concrete tank, make the RCC water tanks have less longevity compared to the fiberglass tank. Specifically, an RCC’s lifetime is about 15 years with minimal maintenance. In order to design an RCC water tank, engineers with a civil engineering background are needed.
Since stormwater typically has tons of debris and sediment, sedimentation chambers are applied upstream of the water tank to capture large pollution particles. Particles tend to settle down with low flow rate. Two chambers cascaded for each inlet to maximize the ability of capturing the particles. A H-shape pipes configuration connects two chambers which is designed to prevent against siphon effect and to minimize convey floating contaminations to the next chambers or water tanks. Following figures show the design of the sedimentation chambers. The chambers need to be clean regularly to maintain the quality of water flowing into the storage tank. Manhole covers are used to cover the sedimentation chambers.
A submersible pump is placed at the bottom of each pump station to send the harvested water from the tank to the net-zero bathroom for toilet flushing. As shown in the following figure, there are two pump stations or pump wells. Each pump station supplies one net-zero bathroom. The station allows access for maintenance of the tank and the submersible pumps. In practice, a pressure tank is usually needed. Due to limited space, the pressure tank for the stormwater storage is placed under the bathroom.
With a given flow rate and slope, the flow depth is unknown. After calculating the flow depth, the geometry and dimension of the drainage can be determined. For the design, uniform flow is assumed. This can occur in a straight open channel with constant slope and cross section. The water depth and velocity are also constant.
Based on the mass conservation, the flow rate of a constant volume flow can be expressed as
Q = VA,
where V is the averaged flow velocity, A is the area of the cross section.
For the uniform flow, by using the Manning equation, the velocity is
V = (α / n) R_{h}^{2/3 }S^{1/2},
Where R_{h} is the hydraulic radius; n is the roughness coefficient; S is a constant channel slope; α is a unit conversion factor:
α = 1 SI units, α = 1.486 U.S. Units.
Thus, the flow rate of the uniform flow is
Q = α/n AR_{h}^{2/3 }S^{1/2}
The most efficient rectangular section has Width: Height=2:1, then
A = 2y^{2}, P = 4y, R_{h}= ½y, b – 2y,
Where y is the water height; P is the wetted perimeter; b is the width of the rectangular channel.
With given flow rate Q and channel slope S, using the most efficient rectangular section with b = 2y , determining the roughness factor based on the material of drainage, the normal depth of the flow can be calculated with following procedures:
A(b) = by = b (b/2) = b^{2 }/ 2,
R_{h}(b) = A/P = by/(b+2y) = 2y^{2}/4y = y/2 = b/4,
Q = α/n A(b) R_{h}(b)^{2/3 }S^{1/2} = α/n b^{2}/2 (b/4)^{2/3 }S^{1/2},
or
b^{8/3} = f(b) = Q 2n/α 4^{2/3 }S^{-1/2}
Solving the last equation, the channel width b is found and the normal depth y can be estimated. The dimension of the drainage can be determined based on the flow normal depth.
Hydrograph and peak flow estimation is a process used in hydrology to analyze and predict the behavior of water flow in rivers, streams, and other watercourses. Hydrographs are graphical representations of water flow over time, showing how the flow of water changes in response to rainfall, snowmelt, or other factors. Peak flow is the highest point of water flow during a storm event. Hydrograph and peak flow estimation is important for understanding the potential for flooding, erosion, and other impacts of extreme weather events. The process involves analyzing factors such as watershed characteristics, precipitation patterns, and land use to develop models that can estimate the magnitude and timing of peak flows. This information can be used to inform flood control and water management strategies.
Hydrologic Calculation
The intensity-duration-frequency curves are usually used for the hydraulic calculation. The flow rate used to estimate the dimension of the drainage is derived from this step. We are going to ignore the initial abstraction and infiltration.
Time of Concentration
Time of concentration indicates the time it takes for runoff from a catchment area to reach equilibrium under a steady rainfall. It is also defined as the longest travel time it takes for runoff to reach the discharge point of a catchment area.
For solving the time of concentration, we are going to use the Soil Conservation Service (SCS) method. In the SCS method, the flow path is divided into three segments: sheet flow, shallow concentrated flow, and channel flow. The segments of the sheet flow and the shallow concentrated flow are ignored since the catchment area of the Earthbag Village is relatively small compared to the cases the equation is being specified for. The channel flow time of concentration is calculated by
T_{c} = L/60V
Where T_{c} is the time of concentration, min; L is the flow length, ft(m); V is the channel flow velocity, ft/s (m/s).
The velocity can be calculated by the Manning equation
V = (1.49 R_{h}^{2/3 }S^{1/2}) / n
Rainfall intensity
The rainfall intensity (I) can be found based on the time of concentration and frequency by using the IDF curves.
Peak Discharge Computation (Runoff Calculation)
Peak discharge is the peak rate of runoff (volume per unit time, typically cubic feet per second) from a drainage area for a given rainfall.
The rational method is used for the runoff calculation:
Q = CI A_{c }(U.S.) or Q = 0.278CI A_{c }(SI)
Where is the discharge, cfs (m^{3}/s); C is the runoff coefficient, dimensionless; I is the rainfall intensity, in/h (mm/h); A is the catchment area, ac (km^{2}).
The blow chart is applicable for storms of 5 to 10-year frequencies. For lower frequency with higher intensity cases, higher runoff coefficients are required because infiltration has less of an effect on runoff.
The rational method is suggested to use in cases with an area less than 250 acres (1.089e+7 ft2). The rational method is best suited for mostly paved areas where interception is nonexistent, infiltration is negligible, and surface retention is small. Those assumptions can be applied on the runoff calculator of the earthbag village.
The Earthbag Village consists of an outer ring of housing domes in addition to an inner ring. An elevation difference between the outer and inner domes influenced the design of the overall pipe systems because rainwater runoff must be collected from both the upper and lower surfaces. It is also for this reason that deep trenches will be used for the storm drain pipe network.
The storm drain pipe network is placed on the outermost edge of the roadway in order to keep pipe maintenance from blocking the entire use of the roadway. This reasoning is applied to the subsurface perforated pipe placed on the innermost edge of the road. Storm drain pipes were also placed surrounding the atrium and directed to the main system. The north and south entrances to the atrium incorporate catch basins for runoff water, in which its placement was based on the elevation changes in the immediate area.
Clean outs were placed into the design in order to ensure proper maintenance of the storm drain pipe network. These are openings in the pipes that allow for debris to be removed. The clean outs are placed at the pipe connections located on the outermost edge of the porous concrete roadway. The pipe connections within the 6 dome clusters and 3 dome clusters are not designed with clean outs. For those connections joining two pipes, a WYE connection is used. Though the installation of a junction box will be seen for connections of more than 2 pipes.
Each 6 dome cluster is designed to include two drains to collect rainwater runoff whereas the inner 3 dome clusters have one drain. In addition, 4 catch basins are placed at key points of the pipe networks. The flow of the runoff water is directed to both the East and West greywater ponds for the capture and cleaning of the runoff water. In the figure below, the drainage flow and the pipe network are illustrated clearly. Additionally, a 2 foot wide rock swale is incorporated into the outermost part of the roadway to collect additional runoff water when the road is fully saturated.
The pathways and walkways of Earthbag Village are composed of two main pavement types: decomposed granite and porous asphalt. Each material demonstrates qualities that are essential to the design and purpose of rainwater management. For instance, the patios to the outer ring domes are made of decomposed granite. This material is commonly used in xeriscaping as a result of its permeable abilities and low maintenance. The main roadway, a fire access road, is composed of porous asphalt. This material is classified as low impact development technology and grants efficient rainwater drainage while supporting a frequently used road.
The outer and inner ring of the main roadway is lined with an impermeable material. The impermeable liner keeps other elements or soils from infiltrating through the vertical plane and keeps water from seeping through.
As the drain rock depth is 27 inches, the impermeable liner covers this depth. An additional 6 inches of this material are also provided as a precautionary measure. Therefore the outer and inner rings of the main roadways each have an impermeable liner that reaches 33 inches in depth. The geotextile material on the other hand is laid parallel with the horizontal plane. The geotextile is placed prior to the drain rock. This material is permeable and will therefore allow water to filter through. Geotextiles are commonly used to improve soil characteristics and reinforce layers of different soil types. As mentioned previously, 27 inches of drain rock is placed above the geotextile, yet another sheet of the geotextile may be placed on top of the drain rock if the design calls for the addition of another soil layer.
The calculations of the diameter of the pipes shall be done using the Hazen-Williams Formula, which includes the discharge rate, coefficient of the material and slope.
Calculations coming soon…
For cost and labor efficiency, the slope is the minimum determined to be effective. This reduces the needed excavation and the pond can be just ~2.3-2.5 feet under the ground level. For this reason in the AutoCAD drawing the slope is a little bit difficult to be seen.
The minimum pond size for the large pond shown below is 16′ diameter and 9 feet deep.
Calculations coming soon…
Water collection (with storage in the central pond) is planned for the Aquapinis, Walipinis, and surrounding roadways. Water catchment for this area has been calculated using the following color coordinated zones: Pink for small structures, Orange for the large structures, and Blue for Roads & Walkways.
The water collection area of each small structure (pink) equals 2079 square feet x 4 structures = 8,316 sq. ft. Using a (conservative for our location) 10-inch annual rainfall* and applying the formula for calculating water harvesting (catchment area x rainfall x runoff) yields: (8,316) X (.833) X (7.48) = 51,885 gallons of water harvested per year from these structures.
The water collection area of each large structure (orange) equals 3,399 square feet x 2 structures = 6,798 sq. ft. Using a (conservative for our location) 10-inch annual rainfall* and applying the formula for calculating water harvesting (catchment area x rainfall x runoff) yields: (6,798) X (.833) X (7.48) = 42,357 gallons of water harvested per year from these structures.
The water collection area of the walkways and central area equals 6,791 sq. ft. Using a (conservative for our location) 10-inch annual rainfall* and applying the formula for calculating water harvesting (catchment area x rainfall x runoff) yields: (6,791) X (.833) X (7.48) = 42,313 gallons of water harvested per year from this area.
*Note: For calculating cistern and pond sizes we used the average annual rainfall for our location of 13.6 ~ 15 in = average of 368.3 mm. For calculating pipe size we used the Daily Critical Rainfall (the maximum daily amount of rainfall in our location) of 1.3″ / 33 mm.
Water will also be collected off the entire Duplicable City Center Hub. Water catchment for this area has been calculated using the following color coordinated zones: Pink for the domes and Blue for the central area. There is a 4th floor cupola that will cover the central area but water will still be collected from this cupola so we have used the zones you see below for simplicity.
The Duplicable City Center footprint for each of the domes (area of the circle) was calculated for rainwater catchment. The area of a 74′ diameter circle equals 4,300 feet x 3 domes = 12,900 sq ft. Using a (conservative for our location) 10-inch annual rainfall* and applying the formula for calculating water harvesting (catchment area x rainfall x runoff) yields: (12,900) X (.833) X (7.48) = 80,485 gallons of water harvested per year from the domes.
Note: For those interested, the actual surface area of each of the Duplicable City Center’s 74′ diameter/35′ high domes (pink) can be quickly calculated using this tool as equalling 8,149 feet.
The area of the central water collection zone (blue) for the Duplicable City Center includes the area shown on the map above (topped with the cupola that will cover much of this area) equaling roughly 3,010 sq ft. of rain collecting space. Using a (conservative for our location) 10-inch annual rainfall* and applying the formula for calculating water harvesting (catchment area x rainfall x runoff) yields: (3,010) X (.833) X (7.48) = 18,754 gallons of water harvested per year from the Duplicable City Center Hub.
*Note: For calculating cistern and pond sizes we used the average annual rainfall for our location of 13.6 ~ 15 in = average of 368.3 mm. For calculating pipe size we used the Daily Critical Rainfall (the maximum daily amount of rainfall in our location) of 1.3″ / 33 mm.
Water will also be collected off of and under our energy infrastructure of solar panels that will cover a total of 7,392 square feet. Using a (conservative for our location) 10-inch annual rainfall* and applying the formula for calculating water harvesting (catchment area x rainfall x runoff) yields: (7,392) X (.833) X (7.48) = 46,058 gallons of water harvested per year.
*Note: For calculating cistern and pond sizes we used the average annual rainfall for our location of 13.6 ~ 15 in = average of 368.3 mm. For calculating pipe size we used the Daily Critical Rainfall (the maximum daily amount of rainfall in our location) of 1.3″ / 33 mm.
Swale creation is part of the One Community water conservation plan, stewardship strategy, and food forest design. In addition to water collection off all the structures of One Community, we will also open source project-launch blueprint the effectiveness and value of swale creation for land restoration, food forest establishment and support, and greywater processing.
A swale is a ditch and berm system designed to halt overland water flow and maximize water infiltration. The design calls for an excavated ditch along the contour lines of a property such that the ditch is always following the level contour of the land. The soil excavated from the ditch is moved to the downslope side to form a berm. It is important to make sure that the top of the berm is level, in order to prevent accumulated water in the swale from finding a low spot and washing out the berm. The entire area is raked smooth, mulched, and densely planted with a broad mix of annual and perennial species. In dry climates it may be necessary to irrigate the plantings until the first rain event, or until the plantings take hold.
A properly designed and constructed swale accomplishes a number of important functions. First and foremost is the retention in the landscape of the maximum amount of precipitation or inflow. As the infiltrated water moves down and out through the soil profile, it enables the growth of trees and other plants upslope and downslope of the swales that would not otherwise survive on the site. The tree cover in turn shades and mulches the swale, maintaining and enhancing the infiltration; as the trees grow, their roots help guide moisture ever deeper into the soil profile. This synergistic feedback loop makes possible the reforestation or afforestation of even the driest regions. The system is expanded with additional swales upslope and downslope across the landscape.
It is important to understand that a swale is NOT meant to direct or divert the flow of water across the slope. Rather, the design and intention of a swale is to HALT the flow of water, so that it collects in the swale and has the chance to sink into the soil. In areas that receive sufficient rainfall, swales can be connected to a series of deeper ponds or impoundments to hold larger amounts of water. These can be constructed to increase the area of infiltration, or designed as permanent ponds.
Understanding the soil structure where a swale is under consideration is important to achieve the aim of maximum infiltration. On most soils, the mulch layer starts the generation of the soils microbiota, which improves the crumb structure and drainage of the soil. In the case of clay, treatment with gypsum (calcium sulfate) followed by mulch, will help the clay flocculate and achieve percolation. In extremely rocky or shale situations, mechanically ripping the bottom of the swale with a dozer shank may be necessary.
As a swale establishes its associated habitat, an accelerated turnover in species composition is seen. The initial annuals and short-lived perennials are soon shaded out by taller, longer-lived trees and shrubs, which in turn are succeeded by slower growing climax forest species. At each stage of this evolution, niches are created for new species, and “edge” increases at the peripheries. Properly managed, each of these niches is an opportunity for developing an ever-widening array of yields.
As the systems of multiple swales extend towards each other, the management of the interswale zone can be maintained as e.g. open meadow, agricultural field, home or village site, etc. Allowing these sites to be surrounded with swale-derived agroforest increases their soil moisture, reduces wind and evapo-transpiration, provides convenient access to wild foods, medicinal plants, and other forest yields. This approach brings Zones 3 and 4 closer to Zones 1 and 2.
Forming swales looks like this:
A swale on contour catches large volumes of water and allows it to soak into the land like this:
Water caught by a swale absorbs into the land like this:
Ripping plow lines on contour, pushes rushing water from the valleys out to the ridges like this:
Excess water from swales is directed to ponds and lakes like this:
Bamboos are an especially useful set of plants for swales. Monopodial (“clumping”) bamboos have very dense root systems, and excel as silt traps. The sympodial or so-called “running” bamboos spread out and form groves of canes that can quickly shade and mulch large areas. Their root systems will seek moisture, and they can spread along a swale for hundreds of feet, mulching and protecting the newly installed swale as they go. Near dwellings or settlements, all greywater can be directed to bamboo groves, which will greedily filter out nitrates and nitrites. There are different species of bamboo that will grow from the equator to the arctic latitudes, and given the wide variety of yields – edible shoots, medicine, craft and construction wood, mulch, fuel, livestock browse, etc. – their judicious selection and placement should be part of any site development.
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