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A study was performed on the University Link and Northgate Link projects in Seattle, WA, to investigate the use of apparent density evaluation methods for the identification of air pockets and plugging issues in the chamber of EPB TBMs. Both air pockets and plugging issues can result from improper soil conditioning and the TBM’s inability to mix the soil properly with the conditioning agents. An apparent density below unity indicates the formation of an air pocket in the top part of the chamber and an apparent density above the virgin soil density points to developing plugging issues in the cutterhead bays and pressurized chamber. From the conducted study it can be concluded that the presented apparent density evaluation methods are an effective way to identify issues in the excavation chamber of an EPB TBM and can be used as a mean to improve the soil conditioning process.

This paper presents a characterisation campaign carried out on granular soils conditioned for EPB tunnelling using a modified direct shear box. The main objective of soil conditioning is the reduction of its shear strength to control the counterpressure inside the bulk chamber. In order to preserve the pseudo-fluid characteristics of the conditioned soil mass, the main concerning para meters are their undrained properties. To characterise the un drained behaviour an adopted watertight direct shear apparatus was used. The purpose of this research is to define a simplified testing procedure for conditioned soil, analysing its feasibility and reliability with resources that can be found at any laboratory or job site. A comparison between the results obtained under dry and conditioned conditions is presented for three different cohesionless soils. The choice of the materials studied has been made in order to cover a wide range within sands grain size.

The aims of this study are to find a solution for the problems (lumping, adhesion, and clogging) encountered with fine-grained sedimentary materials, minimize the time and cost of excavation, and decrease the potential environmental effects due to soil conditioning chemicals used in the process of excavating a waste water tunnel. Therefore, this study will contribute important technical knowledge regarding design and implementation of excavation with TBM to the mining and construction industries as well as for optimization in mechanical engineering. In this research, real-time machine operational parameters recorded by EPB TBM and actual geotechnical parameters in an Istanbul-Buyukcekmece Wastewater Tunnel at seven selected tunnel sections were used as input data for the back analysis and assessment method. The method covers excavated materials with: (1) water and (2) soil conditioning chemicals. The influence of water and soil-conditioning chemicals of different proportions on torque, thrust, advance rate of the TBM, and plasticity and consistency indices of the material were investigated. Finally, integrated data were evaluated by multiple linear regression models.

Tunnelling in difficult and challenging conditions such as soft soils in urban areas is increasing. In this condition, it is important to minimise the possible negative effect of the tunnel excavation, such as settlement or, in the worst case, collapses. To achieve this result, earth pressure balance machines are commonly used. One of the key parameters that must be considered for an optimal management of the EPB-TBM excavation is soil conditioning since the excavated muck must properly transmit the pressure to the tunnel face. Soil conditioning is also necessary to reduce the effect of the problems, such as clogging in clay layers, that can occur during the excavation and that can affect the performance of the tools and of the entire tunnelling process. For this reason, in the last decade, much research has been carried out to understand how to deal with and reduce the effects of clogging and stickiness, using different conditioning additives. These studies have proposed several different test procedures to evaluate the effect of the conditioning on the adhesion of the soil on the metallic parts of the machines. The present research has been carried out with the aim of proposing a new approach and new devices to study clay conditioning with laboratory tests, and the results of many tests carried out with the proposed device are presented and discussed.

Earth Pressure Balance (EPB-) Shields were originally used in fine-grained soils as well as in mixed-grained soils with a content of fines ( d

This paper describes the application of the Italian chabazite-rich tuff of Sorano (Grosseto) as a soil conditioner and slow nutrient fertilizer to a silty-clay soil and a sandy soil. The study was developed by means of batch and column experiments. The objectives of the study were: (1) to evaluate and compare the physical and hydraulic properties of mixtures of soil and natural zeolitite (95:5% v/v) with those of unamended soils, (2) to determine the effects of applying NH 4 + -enriched zeolitites on soils and (3) to model water and solutes movement in two different scenarios, with and without amendment incorporation. Results of column experiments were then modelled to obtain the physical–chemical and hydraulic parameters representative of the soils amended with the NH 4 + -enriched zeolitites. Using synthetic rainwater as eluent, NH 4 + was never detected in the water phase of batches and columns; NO 3 − and PO 4 3 − were both present at high concentrations in batch tests and were leached in column elution tests. NO 3 − displayed very high concentrations at the beginning of the elution whereas PO 4 3 − showed low concentrations and retarded peaks in both amended soil columns. The rationale of the study lies in the belief that inorganic amendments, which improve the physical and hydraulic properties of soils, can lead to minimized leaching of nutrients.

The Line 4 South being constructed in Rio de Janeiro crosses complex geology that includes a long stretch of sand bounded by two stretches of hard, highly abrasive rock. These geological conditions, combined with the fact that the project is located in a distinct urban area, creates a demanding project scenario where special care needs to be taken. After carrying out an evaluation to determine whether to use earth pressure balance or slurry technology, the design of a convertible EPB boring machine that can excavate both rock and soils was developed. This paper outlines the technical difficulties of the project and describes the decision-making process and the solutions adopted. A technical description of the different operation modes of this hybrid TBM and the conditioning process related to each of them is provided. (A)

The Norwegian University of Science and Technology (NTNU), SINTEF Rock Engineering and BASF Construction Chemicals have jointly developed a new test device called the Soft Ground Abrasion Tester (SGAT). The ambition and purpose of the design of the test and the applied test procedure is to replicate an in situ soil – TBM excavation tool contact, in a small and simplified scale. The current development is attempting to bridge a gap when it comes to estimating soft ground and soil abrasivity, as earlier research on e.g. the NTNU/SINTEF Soil Abrasion Test™ (SAT) shows that it does not catch up all driving factors for soft ground and soil abrasivity directly. The paper summarizes the development of the SGAT apparatus, and shows its capabilities to evaluate, quantify and compare how the soil mineralogy, water content, pressure, compaction, and the use of soil conditioning additives influences the wear rate on the SGAT excavation tool. During testing the required torque and thrust are monitored and logged, making it possible to measure various soil–soil conditioning matrixes requirement for operational parameters.

The presence of impurities in biodegradable waste (biowaste) causes problems with the management of waste, among which are additional costs derived from the need to improve pre-treatment of biowaste, loss of treatment capacity and the difficulty selling treated biowaste as compost owing to its low quality. When treated biowaste is used for soil conditioning it can also cause soil pollution. Understanding the reasons why impurities are in biowaste and the factors affecting the percentage of impurities present can be used to determine ways to minimise these negative effects. This article attempts to identify the main causes for the presence of impurities in biowaste. In order to do so, it carries out an empirical analysis of the level of impurities in biowaste from municipal waste collection in two steps. First, a bivariate analysis focuses on significant correlations between the presence of impurities and several variables. Second, the construction of an explanatory model based on the significant relations obtained in the first step, and on literature research, are used to check the stated hypothesis. The estimates demonstrate that the collection system, the global levels of separate collection, the urban density of the municipality and the requirement to use compostable bags may be the main drivers of impurity levels in biowaste.

In earth pressure balance (EPB) shield construction, the “plastic flow state” is difficult to form using the soil dug in the capsule because it can cause three abnormal operating conditions, including occlusion, caking in the capsule, and spewing at the outlet of the dump device. These abnormal operating conditions can, in turn, trigger failure in tunneling, cutter-device damage, and even catastrophic incidents, such as ground settlement. This present paper effectively integrates the mechanism of abnormal operating conditions and knowledge of soil conditioning, and establishes a uniform model of identifying abnormal conditions and intelligent decision support system based on the belief rule-base system. The model maximizes knowledge in improving the soil, construction experience, and data to optimize the model online. Finally, a numerical simulation with specific construction data is presented to illustrate the effectiveness of the algorithm.

Cutterhead torque is an important parameter for the design and operation of earth pressure balance (EPB) shields. Based on the analysis of several completed project cases from job sites, the conventional torque determination model based on experimentation proves rough enough to be improved. Composition and corresponding calculation method of cutterhead torque are presented, taking into account of cutterhead structure, cutting principle and the interaction between cutterhead and soil. Considering a Φ1.8 m EPB test machine in the lab, theoretical calculation following the improved model and test are carried out with three typical types of soils. Calculation and test results indicate that the cutterhead torque varies with geological conditions apparently, and the opening ratio of the cutterhead as well as earth pressure turns out to be the two most important factors in determining the cutterhead torque. The test results also show that the torque calculation formula for EPB shield tunneling can reasonably predict the excavation torque required by the cutterhead in clay soil tunneling, but for cohesionless tunneling, soil conditioning reduces the amount of torque necessary.

Mechanical properties of sand-pebble layer is very unstable, it is unfavourable for TBM excavation. For the reasons of poor soil conditioning and low plastic flow of muck, EPB TBM tunnel construction in sand-pebble layer of Beijing metro has exposed variety of issues: continuous dynamic earth pressure balance is hard to established, mud cake is formed frequently in earth chamber, key construction parameters such as thrust, torque, advance speed can not be controlled in reasonable scopes, which lead to low efficiency of TBM construction. Taking“Xi-Liu”of line 10 lot 11 as an research object, the mechanical characteristics of sand-pebble layer and construction problems of TBM advancing are analyzed, variety of soil conditioning measures are used for improving plastic flow of muck and minimizing construction influence induced by poor geological conditions, meanwhile contrast studies on key construction parameters before and after soil conditioning are carried out. The results indicate that effect of soil condition plays very significant roles in controlling TBM construction parameters and improving advancing efficiency.

Processed municipal sewage sludges (MSS) are an abundant, unwanted by-product of wastewater treatment, increasingly applied to agriculture and forestry for inexpensive disposal and soil conditioning. Due to their high organic carbon and lipid contents, MSS not only is rich in carbon and nutrients but also represents a “sink” for recalcitrant, hydrophobic, and potentially bioaccumulative compounds. Indeed, many organics sequestered and concentrated in MSS meet the US Environmental Protection Agency’s definition of being persistent, bioaccumulative, and toxic (PBT). In a strategic effort, our research team at the Biodesign Institute has created the National Sewage Sludge Repository (NSSR), a large repository of digested MSSs from 164 wastewater treatment plants from across the USA, as part of the Human Health Observatory (H2O) at Arizona State University (ASU). The NSSR likely represents the largest archive of digested MSS specimens in the USA. The present study summarizes key findings gleaned thus far from analysis of NSSR samples. For example, we evaluated the content of toxicants in MSS and computed estimates of nationwide inventories of mass produced chemicals that become sequestrated in sludge and later are released into the environment during sludge disposal on land. Ongoing efforts document co-occurrence of a variety of PBT compounds in both MSS and human samples, while also identifying a large number of potentially harmful MSS constituents for which human exposure data are still lacking. Finally, we summarize future opportunities and invite collaborative use of the NSSR by the research community. The H2O at ASU represents a new resource and research tool for environmental scientists and the larger research community. As illustrated in this work, this repository can serve to (i) identify and prioritize emerging contaminants, (ii) provide spatial and temporal trends of contaminants, (iii) inform and evaluate the effectiveness of environmental policy-making and regulations, and (iv) approximate, ongoing exposures and body burdens of mass-produced chemicals in human society.

Earth pressure balance (EPB) shield tunnelling is considered to be an effective tunnelling method when surface settlements must be avoided by controlling face stability and underground water inflow. EPB technology is applied increasingly to the conditioning of rock masses in which the presence of polluting material is foreseen and must be controlled, or when explosive gases from the rock mass must be prevented from entering in the machine. The use of an EPB machine in ‘closed mode’ can prevent the dispersion of dangerous materials in the underground environment. This study was performed to evaluate the feasibility of using EPB technology in rock masses and the effectiveness of this tunnelling process in terms of soil conditioning, conditioned soil permeability, pressure transmission on the tunnel face, and the ability to extract the material with a screw conveyor. The research was developed with a set of laboratory tests carried out on three different types of rock masses where tunnelling with EPB machines are planned to be constructed in Italy but the results can be easily applied to similar rock mass types. The tests have been carried out both with slump tests and with a specially constructed screw conveyor extraction device. In the paper the most important results are presented and discussed.

Numerous investigations on the quaternary depositions of natural calcareous sediments and their use for soil conditioning have been carried-out in the Baltic region. Locally sourced freshwater limestone were formerly introduced (1950s) for soil liming, due to the absence or limited availability of appropriate industrial materials. Nowadays, with a greater awareness and understanding of the CO2 issues surrounding the production of industrial lime (intensively heated during manufacture), together with increasing costs of its production and transport, attention has returned to previous approaches. The main aim of this study was the identification of geological distribution peculiarities of freshwater limestone depositions, spatial and vertical geochemical variation and modelling of their previous agricultural use in acid soils regions. Geochemical composition data of local lake limestone has been lacking in Lithuania. Studies reveal that the quality parameters of sediments mostly align with the minimum for standard lime requirements (EN ISO 12945:2008), but materials are geochemically diverse even between layers of the same deposit. Tests show calcareous materials are especially rich in total manganese (3500 ppm) and slightly lower was total barium concentrations (490 ppm). Just a few mg kg−1less were total concentrations of silver, boron, cobalt, chromium, copper, gallium, nickel, lead and vanadium. Former use of these sediments for liming purposes with regard to the national hygiene norm (HN 60:2004) controlled elements disclaim direct risks of soil pollution by higher heavy metals and rare elements accumulation. Previous liming studies indicate natural limes offer slow acting degradability compared to industrial products (dust limestone) and longer lasting liming effect. However, heavy metals and rare elements applied to soils are locked in topsoil (diffusion is mainly limited to depth of soil tillage). Unfortunately, cessation of liming and accelerated soil acidification promotes increased element mobility, which raises the risk of higher accumulations in crops, and their transfer to the food chain and/or their transport to groundwater. Santrauka Baltijos jūros regione atlikta nemažai tyrimų, kurių sudėtinė dalis – kalkingųjų kvartero nuosėdų tyrimai ir jų naudojimas dirvai gerinti. Gėlavandenės klintys buvo naudojamos dirvožemiams kalkinti trūkstant pramoninių kalkinių medžiagų. Šiuo metu jomis vėl domimasi, nes jos leidžia išvengti CO2emisijų, susidarančių gaminant pramonines kalkines medžiagas (kaitinant klintis), jų naudojimas yra ekonomiškai patrauklus. Pagrindinis atliktų tyrimų tikslas – nustatyti geologinio paskirstymo ypatumus gėlavandenėse kalkingosiose nuosėdose, horizontalųjį bei vertikalųjį geocheminį pasiskirstymą ir ankstesnio šių medžiagų naudojimo žemės ūkio paskirties rūgščių dirvožemių regionuose išliekamąjį poveikį. Geocheminė gėlavandenių klinčių sudėtis anksčiau Lietuvoje nebuvo tirta. Atliekant tyrimus nustatyta, kad kalkingosios nuosėdos dažniausiai atitiko minimalių standartinių kalkinių medžiagų reikalavimų kokybės rodiklius (EN ISO 12945:2008), bet geocheminė šių medžiagų sudėtis yra labai įvairi net skirtinguose to paties klodo sluoksniuose. Buvo nustatyta, kad išanalizuotose kalkingosiose nuosėdose yra ypač daug suminio Mn (3500 ppm) ir šiek tiek mažesnė Ba koncentracija (490 ppm). Tik keli mg kg−1ar mažiau buvo rasta suminių Ag, B, Co, Cr, Cu, Ga, Ni, Pb ir V. Modeliuojant buvusį šių nuosėdų naudojimą kalkinimo tikslais, vertinant pagal higienos normoje (HN) kontroliuojamų elementų koncentracijas, paneigtas tiesioginis dirvožemio taršos pavojus sunkiaisiais metalais ir retaisiais elementais. Šiomis medžiagomis kalkintuose dirvožemiuose sunkiųjų metalų ir retųjų elementų atsargos yra ilgam imobilizuotos (mobilesnės iš esmės yra tik armens sluoksnyje). Tačiau dėl nutrauktų kalkinimo darbų spartėjant dirvožemio rūgštėjimui, šių elementų mobilumas didėja, taip pat padidėja grėsmė susikaupti augaluose, patekti į mitybos grandinę ir užteršti gruntinius vandenis. Reikšminiai žodžiai:geochemija,horizontalioji ir vertikalioji variacija,dirvožemio kalkinimas,dirvožemio rūgštėjimas,higienos normos

Because of their high nutritional content and soil conditioning properties,. municipal and pulp and paper (P&P) sludges-biosolids-can serve as soil amendments for nutritionally deurived or organically soils on forest sites. Studies conducted over the past 20 years at an experimental forest site in Western Washington, USA, have largely confined the potential of biosolids to increase the productivity of many forest lands. These studies clearly demonstrated that application of biosolids at environmentally acceptable rates will result in growth responses for both young seedlings as well as established stands. Municipal biosolids have been applied to a number of different Douglas-fir stands. Young stands applied at 47 Mg ha-1 showed an average of 72%, 14% and 2% height responses for Site Class IV, III and 11, respectively, over a 10 year period. Thinned versus unthinned 55-yeardd Douglas-fir applied with 142 dry Mg ha-l averaged 43% and 48%, respectively, for the 12 year period greater than controls. Average g...

Agricultural residues have significant potential as a feedstock for bioenergy production, but removing these residues from the land can have negative impacts on soil health. Because of this computational tools are needed that can help guide decisions on the amount of agricultural residue that can be sustainably removed. Models and datasets that can support decisions about sustainable agricultural residue removal are available; however, no tools currently exist that are capable of simultaneously addressing all of the environmental factors that can limit the availability of residue for bioenergy production. This paper presents an integrated framework of models and data that provide a coupled a set of environmental process models and databases that can support agricultural residue removal decisions. Specifically the RUSLE2, WEPS, and Soil Conditioning Index models have been integrated together with the disparate set of databases providing the soils, climate, and management practice data required. The integrated system has been demonstrated for two example cases. In the first case the potential impact of agricultural residue removal is explored. In the second case an aggregate assessment of the agricultural residues available bioenergy production in the state of Iowa is performed.Copyright © 2011 by ASME

Problem statement: EPB tunneling requires that the excavated soil has a plastic and pulpy behavior to be able to apply a stabilizing pressure to the face, but it should also be impervious to counteract filtration forces that could develop ahe ad of the face. The evaluation of this parameter in granular soil, before and after conditioning, is th erefore of key importance for a correct conditionin g agents choice. Approach: A new laboratory procedure for testing the permeabi lity of conditioned soil with foam has been proposed. The tests have been ca rried out at different hydraulic loads, chosen to b e 0.1 bars and 1 bar. Results: The proposed procedure has been applied to determine the behavior of differently conditioned granular soils: a fluvial s and and a pozzolanic soil and has shown that an increasing of the FIR induces a relative increase i n the time required by water to pass through a standard sample, emphasizing, in this way, the effe ctiveness of the conditioning on impermeability of the soil. Conclusion: The tests have shown the laboratory procedure adeq uately captures the behavior of the conditioned soil. Further, the proposed test may also be used as an index for the preliminary definition of the quality of the soil conditioning and suitability for EPB tunneling.

In order to extend the application field of Earth Pressure Balance (EPB) tunnel machines to various soil conditions, the soil to be excavated has to be treated with additives in order to modify its mechanical properties, changing it into a plastic paste. Sometimes the grain size distribution is also changed with the use of fine-sized materials. The performance of the conditioned soil should be evaluated with tests that are able to describe its mass behavior, but very little research has been carried out in this field. Often the choice of the conditioning agent set and its control during the excavation is made on a trial-and-error basis during the excavation process. The slump cone test performed on conditioned material is a fast and low-cost way of checking this behavior both in the laboratory and on the job site. The results of a test program on different conditioned non-cohesive soils using the slump cone test are presented and discussed. The influence of the water content and the amount of conditioning foam has been studied, and the feasibility of this type of test for the control of EPB conditioned soil has been assessed.

EPB tunnelling requires the application of soil conditioning to increase its field of applicability particularly for cohesionless soils. Choosing the most suitable conditioning set for the various soils requires the use of a feasible laboratory test which can permit to define the characteristics of the conditioned soils and provide measurable data. A series of tests has been carried out using a laboratory screw conveyor device which was designed for this purpose and which simulates the extraction of the spoil from a pressure chamber in a similar way as in EPB tunnelling. The tested soils were medium-grain sands with varying amounts of silt and the tested conditioned mixtures were obtained with different water contents and amounts of foam. A simple slump test was also used to analyze the global characteristics of the conditioned soils. The test has shown that the proposed laboratory procedure permits a quantitative comparison to be made between different conditioning amounts and agents on the basis of measurable parameters.

A high frequency grounding network is realized for RF system of Indus-2, 2.5 GeV synchrotron radiation sources being built at CAT, Indore. Proper soil conditioning is made to improve the effectiveness of grounding pits of this network. Various factors influencing the performance of grounding system are discussed to enhance the safety of personnel as well as the protection of equipments. Steps are taken to realize low impedance RF grounding plane for 505 MHz.

The Permo-Pennsylvanian zeugogeosyncline of central Colorado was the site of extensive evaporite deposition, especially in the northwestern part of the trough. Gypsum crops out principally in the Meeker and Dotsero-Eagle areas, pinching out to the S. and E., but sporadic occurrences are known through South Park and as far S. as Coaldale. Primarily Pennsylvanian in age, the gypsum was forced into irregular domes and anticlinal accumulations by Laramide and younger movements. Two major Pennsylvanian gypsum localities occur in the Wellsville area. A third gypsum occurrence is considered to be Quaternary in age. Since 1952 approximately 50,000 tons of gypsum have been removed from these deposits and sold as a soil supplement by the U.S. Soil Conditioning Company of Salida.

This paper presents the results of laboratory test on the feasibility of soil conditioning for earth pressure balance (EPB) excavation in a tar sand, which is a natural material never studied in this respect. The laboratory test performed is based on a procedure and methods used in previous studies with different types of soils, but for this special complex material, additional tests are also conducted to verify particular properties of the tar sands, such as the tilt test and vane shear test usually used in cohesive materials, and a direct shear test. The laboratory test proves that the test procedure is applicable also to this type of soil and the conditioned material can be considered suitable for EPB excavations, although it is necessary to use a certain percentage of fine elements (filler) to create a material suitable to be mixed with foam. The test results show that the conditioned material fulfils the required standard for an EPB application.

The population served by public sewerage systems in Japan is currently 43 million, which is about 36% of the total population. Sewage sludge produced in a year is about 4 million m 3 as dewatered cake, or about 1.2 million tons in dry solid (DS). About half of the cake is incinerated to reduce the volume, and the quantity of sludge finally disposed of is about 2.2 million m 3 in a year. The greater part of sewage sludge is being disposed of by landfill. However, it is becoming more and more difficult to find proper sites for landfill and coastal reclamation, particularly around large cities. The total amount of sludge utilization for beneficial purposes was 310 thousand m 3 , almost all of which was for agricultural use. But it has certain limitations in Japan because of heavy metal problems and other reasons. Therefore, research and development on utilization of sewage sludge for other purposes, particularly utilization as construction materials, has been extensively carried out by the central and local governments, municipalities and private industries. This paper summarizes the recent developments in technologies in this field in Japan. The major results of this study are as follows. (a) Lime incinerated ash can be adequately used as material, soil conditioning additive, backfilling material, roadbed material and asphalt filler. (b) Polymer incinerated ash can be used as material for ceramic products.

Introduction Beijing subway line 14 includes four stations and approximately 2.8 km of tunnels between the Dongfengbeiqiao and Jingshunlu areas of the city. Due to the surface and underground space limitations of this section, a double-track running tunnel instead of two single-track running tunnels was adopted to connect the two stations. The double-track tunnels were excavated by a 10.22 m diameter earth pressure balance (EPB) shield. It was the first time that an EPB shield more than 10 m in diameter was used in Beijing subway construction. Case description The shield, which passes underneath densely built-up areas of the city and is equipped with a spoke-type cutterhead, with balance between the ground pressure and the earth chamber pressure at the tunnel face, is of great importance. Referring to experiences gained in the EPB shield tunneling, attention was paid to the function of soil conditioning and simultaneous backfilling grouting of the shield, and some special designs were considered in manufacturing the machine. Discussion and Evaluation In addition to the agitating rods welded to the cutterhead, two independently driven agitators were added to fully mix everything in the earth chamber. Independent pipelines were arranged for injecting different conditioning agents. Indoor tests in combination with field tests were conducted to find suitable additives and injection ratios of the additives, and determine the mix ratio of the two-component grout for simultaneous backfilling grouting. A scheme was employed for simultaneously injecting the bentonite slurry at 8% concentration and the foam liquid at 5% concentration to condition the excavated soil. The cement–sodium silicate grout was adopted to fill the tail void and the injection volume per ring was 14.1–15.3 m3. Conclusions The performance of the shield and evaluation of the corresponding tunneling technologies are introduced in terms of the shield tunneling induced ground surface settlements. The success of the project is of great significance to Beijing subway construction and underground space utilization. The findings serve as a useful reference for similar projects.