Abubaker Alamailes Thesis Master of Science-Civil Engineering Fall 2011.

Abubaker Alamailes ThesisMaster of Science-Civil EngineeringFall 2011

The University of Texas at El Paso

Examination Committee:

Dr. John Walton Advisor. Dr. Shane Walker Member.Dr. Richard Langford Member.


outlineIntroductionSimulation MethodSimulation ResultsField MethodField ResultsConclusion


Introduction http://www.invisiblestructures.com/stormwater.html


Con. IntroductionLow Impact Design (LID) is intended to deal with these problems LID publications oriented to different climatesObjective: adapt LID concepts to desert southwest conditionsAn efficient passive landscape includedField comparison method


ApproachDesign at household levelOnly passive appropriate for climateStormwater neutral designs for 3 citiesDivide lot into mini-watershedsMini-scale practicesWater balance of P,R, ET, and SNative vegetationEquivalent initial costField and simulation studies


LID DesignThe Model House


LID Design Con. Mini-Watersheds Options.Runoff Paths.Option 1.Option 2.


LID Design: LID practices Selection, and Placement. Locations of LID Practices and Flow Path.


LID Design Con. Cross Sections of a Bioretention Cell and a Vegetated Swale.


LID Design Con. French DrainImpermeable Mulch


LID Design Con. Bioretention SizeSCS Method for small watersheds. Runoff discharge (in):Initial abstraction: Ia = 0.2S,

Runoff volume (R) = Q (in) * Awatershed (acre) Bioretention Volume= (Psot- R) (Pre-R)= A**D

Surface CoverPre-developmentCNDesert with poor natural landscape of shrubs and grasses.77Post-developmentPaved street, roofs, driveways, and sidewalk98gravel mulch with impervious weed barrier96Highly porous 1ft layer of gravel and sand (the surface of the bioretention units)0


LID Size Results.Bioretention/Capture El Paso 24%Albuquerque 21%Phoenix 22%Option 1 (Lot)Option 2 (Lot + street)


Climate Data AnalysisAnnual Statistical Analysis For the Climate data from 1991-2010

Analysis categoryEl PasoAlbuquerquePhoenixPrecipitation, inNet Precipita-tion, inTemperature, FPrecipitation, inNet Precipita-tion, inTemper-ature, FPrecipitation, inNet Precipita-tion, inTemperature, FMean8.966.6365.79.636.6757.78.316.4775.1Std. Error of Mean1.161.020.180.680.560.191.321.180.18Median8.475.7267.59.817.1958.37.625.4175.0Mode0.000.0078.110.020.1873.90.000.0092.8Std. Deviation5.204.5515.23.032.5116.15.885.2615.7Variance27.120.82329.166.2926034.6127.6245Range23.5419.776.812.810.377.527.123.873.8Maximum23.519.799.113.310.591.927.123.8106Number of days when P>054.069.040.0Number of days when Net P>026.031.022.0


Mean Monthly Precipitation and Net Precipitation from 1991 -2010 AlbuquerquePhoenixEl Paso


Passive landscapeNative Vegetation

Scientific NameCommon NameTypeHeightFtWidth FtEvergreen Or DeciduousWater RequirementsCeratoides LanataWinterfatShrub32EvergreenLowLarrea TridentataCreosote BushShrub86EvergreenLowKoberlinia SpinosaCrucifixion ThornShrub57EvergreenLowAtriplex CanescensFour Wing SaltbushShrub68Simi-EvergreenLowLeucophyllum FrutescensTexas Sage/RangerShrub4-84-8EvergreenLowAcacia BerlandieraGuajilloShrub1212DeciduousLowProsopis GlandulosaHoney MesquiteTree3030DeciduousLowChiloposo LinearisDesert WillowTree2520DeciduousLowFraxinus greggiiGreggs AshTree158Semi-EvergreenLowQuercus ArizonicaArizona White Oak Tree3530EvergreenLow


Vegetation Root SystemRoot System for Some Chihuahuan Desert Plants. Honey MesquiteDesert Zinnia (ZIAC) and Snakweed (GUSA)


Landscape Water balance

Soil moisture storage: Vs = * ((L+1) * (B+1)) * D

-Excess


Con.. Landscape Water balanceEvapotranspiration (ET)

Vegetation LocationET rate (inches/year)Salt cedar Gila River, AZ 56Salt cedar Middle Rio Grande, NM 42-57Salt cedar Middle Rio Grande, NM 34-49Salt cedar Colorado River near Blythe, AZ 28-30Cottonwood Middle Rio Grande, NM 65-85Cottonwood Middle Rio Grande, NM 44-53Cottonwood San Pedro River, AZ 19-28Mesquite San Pedro River, AZ 27Mesquite San Pedro River, AZ 25-26Honey mesquite Colorado River near Blythe, AZ 19Russian olive Middle Rio Grande, NM 42-50Ponderosa pine Northern AZ, high elevation 20Ponderosa pine Nevada and northern NM 11--19Pinyon-juniper Northern AZ, mid-elevation 16Pinyon-juniper Nevada 12Grass Middle Rio Grande, NM 2.8-23Shrub Middle Rio Grande, NM 0-14Mixed; low elevation Middle Rio Grande, NM 0-16Xerophytes Nevada 9-12Sagebrush Nevada 12Sage and bitterbrush Nevada10-18


Con.. Landscape Water balanceET volume = Avegetation crown area (acre) * Ave ET (in)

Precipitation: P volume = Abioretention (acre) * P(in)

Runoff: R volume = R (in) * Awatershed (acre)

Vegetation area subdivisionAve ET (in/year)Depth of root system (ft)100 % trees 0% shrubs251075 % trees and 25% shrubs21850% trees and 50% shrubs16725% trees and 75% shrubs1260% trees and 100% shrubs75


Simulation


Landscape Differential CostEPA cost calculator tool. Low estimate & High estimateInitial, 3, 6, 10 years costAnnualized Cost (30 year loan at 5% interest)Comparison categories: Annual water useAnnual water costVegetation Maintenance

CityWater rate, $/1000 gallonEl Paso4.5Albuquerque1.1Phoenix3.6


Landscape ResultsEl Paso: Option 1 Option 2Option 1 Option 2Alb: 77% 85% 34% 37%

Pho: 74% 81% 27% 30%


hmmmmmmmm


Accidental case 1


Accidental case 2


Landscape Differential Cost Results

CityComparison CategoryLow Estimate High estimateConventional PassivesavingConventional PassivesavingEl PasoWater use gallons/ year 20,0000100%49,0000100%10 years cost $ 22,000 $ 12,000 45% $ 44,000 $ 25,000 43%annalized cost $ 1,900 $ 950 50% $ 3,900 $ 2,000 49%AlbuquerqueWater use19,0000100%49,0000100%10 years cost $ 21,000 $ 12,000 43% $ 43,000 $ 25,000 42%annalized cost $ 1,800 $ 950 47% $ 3,700 $ 2,000 46%phoenixWater use20,0000100%49,0000100%10 years cost $ 21,000 $ 12,000 43% $ 44 $ 25,000 -56718%annalized cost $ 1,900 $ 950 50% $ 3,800 $ 2,000 47%


Field MethodSoil Moisture EnergyVolumetric water content (VWC%)Soil suction (cetibars)TDRTensiometer


Field Study. Con


Field Study ResultsA2A3


Field Study Results.. Con.B2


Conclusions & RecommendationsConclusionsLush vegetation without wateringNo detention ponds or lined arroyos neededLowers development costsLowers homeowner costsReplaces equipment and watering with knowledgeBeautifulRecommendationsField testsExamine other options: infrequent watering, soil amendments, larger scales, commercial developments, 100% capture


AcknowledgementsMy FamilyDr. WaltonMy committee My friends


Questions ????

ThanksOr????


Landscape ResultsEl Paso: Option 1 Option 2Option 1 Option 2Alb: 77% 85% 34% 37%

Pho: 74% 81% 27% 30%

Thank you Dr. WaltonFirst I would like to thank my committee for taking time reading my thesis and being here today for the final examination. I , also, would to thank all of the my audience for attending the defense of my thesis.

My thesis is about Adaptation of low impact design to the desert southwestIt is presented to the faculty of the graduate school as partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE in Civil Engineering

*Before I start presenting my work, I would like to introduce my committee. My examination committee includes : The committee chair and my monitor Dr. John Walton. Professor in CE Dr. Shane Walker, Associate Professor in the Department of Civil EngineeringAnd the last and not the least Dr. Richard Langford, Professor in the Department of Geological Sciences. *Here is my presentation outline First I will start with an introduction to the problem that my study is dealing with. Then, I will explained the methods that I followed and the results that I obtained Before I go over the conclusions and the recommendations.

*My study is about stormwater management problems that ate resulted from the expansion of the development. As it can be seen in this picture substituting the pre development conditions of pervious surface (soil+ trees, grasses) with the post development conditions of impervious surfaces pavements ( streets, roofs, sidewalks) has changed the hydrologic system significantly. When the site was not developed, it had a grate infiltration rate, good base flow (groundwater level) and little runoff. However, After developed the runoff I is increased and the infiltration ,the groundwater recharge , and the evapotranspiration rate are reduced. The second picture shows the hydrograph of the site with the post and pre development conditions. total and the peak of the stormwater discharge are increased and the concentration time of the stormwater discharge became much shorter. *The traditional way of treating this problem is to direct the runoff to a large scale detention pond away from the site. (take the water away from the site and use the municipal water to water the plants). Low Impact design is a relatively new technique (firs used in 1993 in Pierce County) that intended to deal with these problems. The technique is base on capturing the stormwater discharge at a close point to the source and detaining the runoff to have a longer period of time for infiltration. The publications of this technique have been used in many different states with different climate. This study aims to adapt the low impact design to the arid climate of the southwest, and use this technique to preserve and maintain the hydrologic system. It, also, aims to design a passive rainwater landscape. The study includes, in addition to the LID design, a field study that shows how to monitor the change in the soil moisture which can be used for future studies to compare between the design the actual measurements. *The approach of this study is to design a Integrated management practices consisting of some LID applications. Just passive practices are used and no expensive tanks included. Passive LID practices store water naturally in highly porous backfill (sand and gravel). The design generalized for three large cities in the Desert Southwest including El Paso, Albuquerque, and Phoenix and twenty years of historical precipitation and temperature data was used. The idea of the LID depends on dividing the lot to mini-watersheds: EPA definition for watershed is that watershed is the area of land where all of the water that is under it or drains off of it goes into the same place. one small scale LID practice or more will be designed to capture the stormwater discharge generated from this watershed. To preserve the hydrologic system of the watershed, the LID practices are sized to capture the mount of discharge that exceeds the amount that would be generated before the area is developed. The stormwater runoff that would be captured by the LID practices and stored in the soil will be used to design a passive landscape where water balance of the water storage in the soil , the precipitation, the captured runoff and the evapotranspiration will be used. In the design, plants shouldnt be irrigated after the root established, for that native vegetation with low water requirements. The study assumed that the initial cost of the conventional landscape and the passive landscape is equivalent. *Here is the general plane of model house. It can be seen that the roof has three main subdivision. The write side of the yard is limited. The location is assumed to take place in the three representative cities where the soil is deep loamy soil and the water table is deep enough to be ignored in the design. These assumptions were taken into account because they dominate a considerable area in the three cities. *The first thing that needs to be determined in order to divide the lot to mini-watersheds is the direction of the runoff. Each watershed has impermeable area and a space area where a LID practice can be installed to capture the runoff generated inhere. Based on the slop direction of the impermeable surfaces (roof subdivisions, driveway , sidewalk and street, two options of mini-watersheds divisions were conducted. Both options have 6 mini-watersheds; however the half of the street is added to watershed D1. this option can be applied if every single house contribute in the stormwater management or the entire residential subdivision. *For this study, the system was designed and modified to be as simple as possible where no pipes or subdrains were included. Four LID practices were selected to form a concrete IMP system. The IMP consists of: bioretention units (bioretention cells and vegetation swale) linked by a French drain, and gravel mulch padded with pervious weed barrier. The lawn is generally sloped toward the street, but inside, it is contoured so the runoff is directed toward the bioretention units. Each unit is gently sloped, so when flooded the excessive water will be transmitted by the French drain to the next unit. The last unit is linked to the adjacent street, so if all of the lawn is flooded the water will be moved to the street to be captured by the domestic drainage system. The overflow would not happen unless a larger storm than the ones occurred in the last twenty years is encountered.

*Here are the designs of the bioretention cell and the vegetated swale:The Bioretention cell has high porous backfill under the vegetated surface. The upper six inches of the porous backfill is sorted coarse gravel, through where water can soak into the lower six inches of high infiltration rate fine sand with an effective porosity of .Permeable plastic screen is installed between the two layers for prevention of weed growth. Temporarily storing the water in the porous gravel during infiltration eliminates concerns about safety and vectors of (e.g. mosquitoes). The bioretention edges are slope by 1:2 to control any erosion that may be caused by the flow.The function of the vegetated swale is the same with the bioretention cell. However, it is selected to be installed in the watersheds 2 and 5 because of the limited widths in the lawn area. To deal with this width limitation, the storage capacity of the swale has to be higher than what is in the bioretention cells. For that, the fine sand layer in backfill is 3.6 inches thicker than in the bioretention cells

*The French drain line, figure (2.8), consists of simply lined trenches filled with sorted coarse gravel and gently sloped to transfer the water to and from the bioretention units. The design is simplified where no pipes are used in order to reduce the cost and to facilitate the operation process. The French drains are 1 foot deep and 1 foot wide. Perforated plastic is installed in the middle for reduction of water evaporation, and impermeable plastic surrounds the trench for prevention of weeds growth and to prevent the water from infiltrating into the soil in this area where no plants are grown. French drains line is an important component in this Integrated Management Practices (IMP) system. It has more than one role to play in this (IMP) system: 1) Grabs the water of the drip line from the roof and conveys it to the bioretention units. 2) Passes through the yard and connects the bioretention units to each other to forward the overflow from the flooded units to the next one and then to the street. 3) Collects the runoff from the rest areas besides the line, which are gently sloped toward it, and transmits it to bioretention unitsThe remaining area in the lawn, after contouring the surface and implementing the other previous IMP components, is covered by mulch. Usually, mulch is consisted of pervious weed barrier covered by 1 to 2 inches of gravel or coarse sand. However, pervious weed barrier is replaced with impervious one this design in order to capture more water from the spots in the yard other than the bioretention units. *the design aims to capture the excessive runoff that results from the change of the site surface conditions. A method was developed to estimate the pre and post development runoff based on the Runoff Curve Number (SCS) method, which the most practical method for small scale watersheds. Initial abstraction (Ia) is all losses before runoff begins. It includes water retained in surface depressions, water intercepted by vegetation, evaporation, and infiltration.S is related to the soil and cover conditions of the watershed through the Curve Number (CN). The value of curve number (CN) reflects the degree to which land surface conditions will generate runoff. The difference between the Post and Pre development runoff volume = to the bioretention volume.*The results show that bioretention surface area is between 20 to 24 % of the impermeable area base on the location. We can see in the second option when the street added to the capture area approximately the same ratio of bioretention area is needed, however its required about 60% extra space in the adjacent part of the yard. Capturing the runoff from the street will provide more water for plants use. *This table shows the annual statistical analysis of the precipitation and the temperature data for El Paso, Albuquerque, and Phoenix from 1991-2010. The analysis included, in addition, the statistical analysis of the net precipitation, which refers to the precipitation that exceeds the Initial abstraction and causes runoff. It can be seen that Alb. has the highest annual average precipitation and net precipitation followed by El Paso and then Phoenix. It has also the highest number of average rainy days per year and the highest number of days/year when the runoff occurred. On the other hand, largest amount of precipitation occurred in these twenty years was in phoenix where 27.1 inches were obtained in one year. *The distribution of the average monthly values of precipitation and the net precipitation shows that Alb. Has the best distribution of the data over months. El Paso has the highest average monthly values. But it concentrates in the period of the year from June to September. The average monthly values in phoenix is lower than El. And Alb, and it is approximately zero in June.*The designed landscape for this study is completely passive; therefore, grasses and high water consuming plants are excluded. Since the design is generalized to three cities in the region the shrubs and trees are carefully selected to be native for all of the cities. The selected shrubs and trees, shown in, have low water requirements*In addition, these plants have wide and deep root systems, which allow them to reach the water stored in the soil away from them. Therefore, they can be grown not only in the bioretention units but also in the area around them.

*The general balance equation that is used for the landscape design simulation is:S = Change in the volume of available water storage in the soil (cu ft).P= Precipitation (cu ft).R= Runoff (cu ft).ET= Evapotranspiration (cu ft).Water storage that is included in this design is the water retained in soil at the area of the bioretention units, and that is available for plants. The plant available water is the unbound water held in soil and available to the plant for uptake. This water falls into the range between two soil water contents the dry end (wilting point) and the moist end (field capacity). Field capacity is the percentage of the water content () remaining in the soil after 48-72 hours of a gravitational drainage when the soil has been saturated by a significant irrigation or precipitation events.The wilting point is the water content in the soil at what the plant reaches the wilting condition. the assumption for the stored water section is to add 1foot to each side of the bioretention unites. Regarding to the lower boundary, it is determined by the root depth, which differs between shrubs and trees with 5 ft for shrubs and 10 feet for trees. The root depth is averaged when the vegetation area has both shrubs and trees *The ET values in the table were used in the simulation. These values are provided by Betsy Woodhouse (2007) who collected the data from different federal and state agencies and universities across Southwest. According *The table shows the values of the ET that were used for different ratios of trees and shrubs that may be desired. It shows, also the averaged root depth that used for the water storage boundaries. **This step is to compare the cost of the conventional landscape and the cost of the passive landscape that is designed in this study.The cost estimation is conducted using a cost calculator tool provided by the Environmental Protection Agency (EPA). The calculate tool is designed to calculate the low and the high cost estimate of converting a conventional landscape to a passive one.the cost of the initial, 3 year, 6 year, 10 year, and average annual costs for the conventional landscape and the passive landscape are compared for the three studied cities. The comparison categories includes: the initial landscape cost, the water cost due to irrigation, vegetation maintenanceThe water rates are taken from the water utility official website of each city. The rates (table) are calculated based on the number of irrigations required per month and the amount of water needed per irrigation. *These graphs demonstrate the design of the passive landscape in El Paso. The results show that when the green area includes 100% shrubs about 84% of the lawn can be covered by the water stored in the soil at the bioretention units once the root established. And this ratio reduced to just 33% when trees just grown in the lawn. The ratio of different ratios of trees and shrubs are between these two values. the less shrubs area can be covered in Albuquerque than El Paso, however approximately the same area of trees can be covered in both cities. This conflict is related to the different climate condition and to the size of the bioretention storage.Phoenix can provide smaller green area at all cases of shrub/tree ratio. The graphs in the right show the percentage of the total lot area that can be covered by in El Paso based on the ratio of trees and shrubs desired. For example if 60% of the green area is wanted to be trees that means 30% of the total lot area can be green. This percent can be increased to about 40% if the all the runoff is captured. *Does it work????

Here are tow accidental cases located about 2 miles from this building.

*The first case is a natural arroyo located at Mesa and waymore. The arroyo receives the runoff from the impermeable surface of the adjacent subdivision, commercial center, barking lot and streets. We can see the natural green area *The second case is located at schuster & Stanton Naturally existed. *The results of the low and high estimate differential cost between a conventional landscape and a passive landscape shown in this table.In the low estimate 20,000 water gallons/year can be saved when passive landscape is used. And 49,000 according to the high estimate in the three cities. Average of about 50% of the annual and the ten years cost can be saved for the three cities. *The porous of this study is to see the change in the soil water energy with time and see the possibility of using this method for future studies to monitor the change in water balance of the designed passive landscape and compare the actual measurements with the theoretical values. In this study, the water content and the soil suction were measured for 10 months at five stations placed at two different locations with different conditions. The first site is a single family residence that already has a simple Low Impact Practices and landscape, located at Turney Drive, El Paso, TX. Three of the five stations were installed in here and labelled as A1, A2, and A3. The second location, where the other two stations (B1 and B2) were installed, is at a desert location by El Paso about 15 miles toward the northwest from the first location.TDR (Time Domain Reflectrometry) was used to measure the volumetric water content of the water section between the TDR rods. It measures the traveling time of electromagnetic signal between rods through and interprets to VWC% on the screen. Tensiometer reads soil suction directly in the field. It consists of a tube filled of water with a porous ceramic tip attached on one end and a vacuum gauge and airtight seal on the other.*This picture shows the location of the three measurement stations at the residential house on Turney street. They were placed in different positions in the yard. Station A1 was placed by the carport beside a French drain. And the A2 was placed in a small natural depression and, A3 was placed in the NW corner at a point close to the water drip line from the roof. The samplers were built in the sites in order to measure the volumetric water content and the soil suction of the soil water at five constant stations at the same soil depth.The station construction was to have 2 gallons bucket and cut it at height of 6 inches and insert it in prepared fitting hole. The measurement of the TDR is averaged over the waveguide, which is controlled by the TDR rod length. On the other hand, the soil suction was measured for the soil surrounding the ceramic tip whose length is shorter than the TDR rod length. To be consistent and reliable over the entire measuring period, the tensiometer was inserted at a soil depth where the center of the ceramic tip meets the center of the TDR rod. Therefore, the coring tool of the tensiometer was marked at the distance that should be inserted. Moreover, a raising plastic tube was made to hold the tensiometer at the desired depth all the time*Here are two examples of the results of the soil moisture measurements. at the drought period the change in the water content and the soil suction. From the graphs we can see that the relationship between the soil suction ant the water content is inverse on when the water content increases the soil suction decreased. It can be seen that in February when a precipitation event occurred the water content and increased at station A3 but not at station A2. that is because station A3 is located under the water drip line from the roof and the water reaches it quickly. On the other hand station A2 located in the middle of the yard where the water that reaches the station come from runoff which needs a large storm to be generated since the area around the station is permeable. *The stations that were installed at the desert have higher soil suction and lower water content values than the other station. The soil at this station loses the water quickly. Quicker than the soil at the station located at the residential house. *This study came to conclusions that the lush vegetation can be grown without watering throughout the year. The stormwater discharge can be captured at a close point to its source and preserve the hydrologic pattern of the area.No need fro expensive detention ponds or lined arroyos to capture and convey the runoff. The study provide a low cost design that can save money for the developer where no need fro a regular irrigation systems and a big sewer system and for the owner where less water and maintenance will be required fro the landscape. Instead of taking the stormwater away from a developed watershed and treat it at expensive facilities and then use the municipal water to water the vegetation. The water can be retained in the watershed and the hydrologic system can be preserve.The design encourages to have greener environment which is of course more beautiful than the desert view.

The recommendations of this study for future study includeUsing the field test to compare between the simulation results and the actual measurements.Examine other options like watering the vegetation once or twice a year at the certain times when it is drought and see how that can increase the green area. Enhance the soil properties to store more water. Try the design for larger watersheds such as residential subdivision or commercial developments.Design to capture the entire amount of the stormwater runoff and see how large the bioretention size should be and how large green area can be passively covered. ***These graphs demonstrate the design of the passive landscape in El Paso. The results show that when the green area includes 100% shrubs about 84% of the lawn can be covered by the water stored in the soil at the bioretention units once the root established. And this ratio reduced to just 33% when trees just grown in the lawn. The ratio of different ratios of trees and shrubs are between these two values. the less shrubs area can be covered in Albuquerque than El Paso, however approximately the same area of trees can be covered in both cities. This conflict is related to the different climate condition and to the size of the bioretention storage.Phoenix can provide smaller green area at all cases of shrub/tree ratio. The graphs in the right show the percentage of the total lot area that can be covered by in El Paso based on the ratio of trees and shrubs desired. For example if 60% of the green area is wanted to be trees that means 30% of the total lot area can be green. This percent can be increased to about 40% if the all the runoff is captured. *

Abubaker Alamailes Thesis Master of Science-Civil Engineering Fall 2011.

Documents

Transcript of Abubaker Alamailes Thesis Master of Science-Civil Engineering Fall 2011.