VI preferential pathways : rule or exception

Trichloroethylene (TCE) releases from leaks and spills next to a large government building occurred over several decades with the most recent event occurring 20 years ago. In response to a perceived conventional vapor intrusion (VI) issue a sub-slab depressurization system (SSDS) was installed 6 years ago. The SSDS is operating within design limits and has achieved building TCE vapor concentration reductions. However, subsequent periodic TCE vapor spikes based on daily HAPSITE™ measurements indicate additional source(s). Two rounds of smoke tests conducted in 2017 and 2018 involved introduction of smoke into a sanitary sewer and storm drain manholes located on effluent lines coming from the building until smoke was observed exiting system vents on the roof. Smoke testing revealed many leaks in both the storm sewer and sanitary sewer systems within the building. Sleuthing of the VI source term using a portable HAPSITE™ indicate elevated vapor TCE levels correspond with observed smoke emanation from utility lines. In some instances, smoke odors were perceived but no leak or suspect pipe was identified suggesting the odor originates from an unidentified pipe located behind or enclosed in a wall. Sleuthing activities also found building roof materials explain some of the elevated TCE levels on the 2nd floor. A relationship was found between TCE concentrations in the roof truss area, plenum space above 2nd floor offices, and breathing zone of 2nd floor offices. Installation of an external blower in the roof truss space has greatly reduced TCE levels in the plenum and office spaces. Preferential VI pathways and unexpected source terms may be overlooked mechanisms as compared to conventional VI.

EKSPLORASI ETNOMATEMATIKA NGADHU DAN BHAGA DALAM KAITANNYA DENGAN PEMBELAJARAN MATEMATIKA PADA MASYARAKAT DESA UBEDOLUMOLO KABUPATEN NGADA

This study aims to determine: (1) to identify the structure of ngadhu and bhaga in Ubedoulumolo Village of Ngada District. (2) Explain the relation of ngadhu and bhaga to mathematics learning in school. The research method used is qualitative with an ethnographic approach. The subjects of this study consisted of three informants (pengu chief, and traditional elders of pengu and gelo tribe). Using observation and interview techniques, supported by documentation, and using qualitative descriptive analysis. The results of the study showed ngadhu and bhaga has related to mathematics, that is the geometry concept. The geometry concept found in ngadhu is: (1) pole ngadhu (made of sebu tree) in the form of a tube; (2) base of ngadhu is composed of a stone in a circle; (3) the roof of ngadhu (material of reeds and palm fibre) in the shape of a cone; (4) bhenga (2 roof support posts) in the form of a beam; (5) mangu (NOK pole) shaped beam; (6) sobhe (head ngadhu made of bamboo) shaped tube; (7) paja (roof truss of bamboo) formed triangle, rectangles, trapezoid. The geometry concept in the bhaga building are: (1) bhaga in the form of the beam; (2) roof (made of reeds) in the shape of a trapezoid and triangular prism; (3) pole shape of beams and tubes; (4) Ube (wall made of plank wood fai) shape of the rectangle; (5) Dawu (arranged boards) with carvings in the form of circles and triangle; (6) Soku bhotha and soku wi’i ( as a roof truss made of bamboo) shape tube rectangle, square and triangle. Geometry forms that exist in the ngadhu and bhaga in the Ubedolumolo Village are lines, angles, triangle, square, rectangle, trapezoid, circle, beam. Tube, cone and triangular prism.

STUDI EKSPERIMENTAL KERUNTUHAN RANGKA KUDA-KUDA BAJA RINGAN PADA ATAP RUMAH DAN SEKOLAH

Increasingly expensive price of quality woods and difficulties of workmanship, it makes people switch from wood to lightweight steel as a roof truss. The use of lightweight steel as truss becomes popular because of the fast workmanship dan durability of the material. Many cases show that lightweight steel truss at school and house collapsed and caused a fatality. This lightweight steel truss study was carried out on a full scale with a span of 6 m and a slope of 300, while the loading test pattern at the placement points of battens was like truss in the community. The goals of this study to measure and observe several parameters including weight, maximum capacity, stiffness, ductility, price, length of work, and failure pattern. From testing, the result shows that lightweight steel truss has dead weight, maximum capacity, stiffness value, ductility value, price, working time, and failure pattern respectively of 21,3 kg,734 kg, 91,18 kg/mm, 2,97, Rp 1.740.000, 2 days, and failure pattern is buckling on the diagonal top chord. The result of this research indicates that lightweight steel truss can be used in the community with the limitation of using metal roof coverings instead of concrete or ceramic and the distance between the truss max 1,2 m.

PERBANDINGAN STRUKTUR DAN BIAYA BANGUNAN RANGKA ATAP ANTARA MATERIAL KAYU & BAJA RINGAN (Study Kasus Gedung Fakultas Teknik dan Ilmu Komputer UNISI)

The existence of a roof in a building is very important considering its function to protect the entire space below it against the influence of temperature and weather. Along with the development of science and technology, the use of wood construction specifically as the structure of the roof frame has begun to be replaced by cold-formed steel construction because the need for wood as the base of roof truss is increasing and the scarcity of trees with good wood quality makes the wood difficult to obtain and the price too become relatively expensive. Comparison of the structure of cold-formed steel roof truss and wooden roof truss is carried out with the load calculation stages in accordance with SKBI 1987 with a combination of loading in accordance with SNI 1729-2002 regulations and SNI 03-2000. Then analyzed using methode of joint to produce rod forces and from these results planned dimensions for the compressive rod and pull rod. Cost calculation is used with SNI analysis method. The results of the calculation of the structure of cold-formed steel roof truss are obtained by the profile of C. 75.75, while the structure of the wooden roof truss is obtained wood dimensions of the size of 7/10. The cost of a cold-formed steel roof frame is Rp. 91,316,000.00, while the cost of wooden roof truss is Rp. 52,972,000. This fee has a disagreement of Rp. 38,164,000.00. Although relatively more expensive, the use of cold-formed steel material has several advantages that are not worshiped by wood material, this material can be made with a variety of stretches, stronger, safer, more durable, not eaten by termites, fire resistant, lightweight and easily assembled material, and the installation is faster when compared to using wood. Abstrak Keberadaan atap pada bangunan sangat penting mengingat fungsinya untuk melindungi seluruh ruangan yang ada di bawahnya terhadap pengaruh suhu dan cuaca. Seiring dengan perkembangan ilmu pengetahuan dan teknologi, penggunaan konstruksi kayu khususnya sebagai struktur rangka atap sudah mulai digantikan dengan konstruksi baja ringan karena kebutuhan akan kayu sebagai bahan dasar rangka atap semakin meningkat dan semakin langkanya pohon dengan kualitas kayu yang baik menyebabkan kayu susah didapat dan harganya pun menjadi relatif mahal. Perbandingan struktur rangka atap baja ringan dan rangka atap kayu dilakukan dengan tahapan perhitungan beban sesuai dengan SKBI 1987 dengan kombinasi pembebanan sesuai dengan peraturan SNI 1729-2002 dan SNI 03-2000. Kemudian dianslisis dengan menggunakan metode titik buhul untuk menghasilkan gaya-gaya batang dan dari hasil tersebut direncanakan dimensi untuk batang tekan dan batang tarik. Perhitungan biaya yang digunakan dengan metode analisa SNI. Hasil perhitungan struktur rangka atap baja ringan diperoleh profil C. 75.75, sedangkan struktur rangka atap kayu diperoleh dimensi kayu ukuran 7/10. Biaya pada rangka atap baja ringan yaitu Rp. 91.316.000,00, sedangkan biaya pada rangka atap kayu yaitu Rp. 52.972.000. Biaya ini berselisih Rp. 38.164.000,00. Meskipun relatif lebih mahal, pemakaian material baja ringan memiliki beberapa kelebihan yang tidak dipuyai oleh material kayu yaitu bahan ini dapat dibuat dengan bermacam bentangan, lebih kuat, lebih aman, lebih awet, tidak dimakan rayap, tahan terhadap api, materialnya ringan dan mudah dirakit, dan pemasangannya lebih cepat bila dibandingakan menggunakan bahan kayu.