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Construction & Contractors/Questions Answered by Expert Robert Cummings, P.E.
| Subject | Date Asked |
| FOUNDATION ON ROCK | 2/6/2012 |
| Q: I have to design foundation of 3-storeyed building each column carries service load around 500 kN. ... A: Although the service load is only 1/10 of the recommended bearing capacity you should adopt a ... | |
| Rock Anchoring | 1/14/2012 |
| Q: Mr. Cummins, I work in an underground facility. It is surrounded by rock on all sides. I have ... A: I don't blame you on being nervous about the all-thread. Because it is so widely available it can ... | |
| rock stability | 1/8/2012 |
| Q: "I'm helping an NGO in a Skywalk feasibility study ,this project has humanitarian target to improve ... A: You are proposing a fascinating project and I wish you the best of luck with it. I would love to ... | |
| Blasting Vibration | 12/12/2011 |
| Q: I'm using horizontal acceleration that i get from velocity differentiation to measure blasting ... A: Waveforms, whether displacement, acceleration, or particle velocity, represent particle excitement ... | |
| Vector Sum | 12/7/2011 |
| Q: How is Vector Sum calculated from the data on a blast report? An example of the data on a typical ... A: Actually, the machine calculates the vector sum at all points along the time history. They don't ... | |
| Vector Sum | 12/7/2011 |
| Q: How is Vector Sum calculated from the data on a blast report? An example of the data on a typical ... A: The vector sum is the square root of the sum of the squares of the parameters at any given time. ... | |
| PPV from vibratory hammers | 12/7/2011 |
| Q: I am tasked with driving 4 foot diameter piles approximately 30 feet deep into previously disturbed ... A: This is an interesting question. Your piles at 4 ft diameter are pretty healthy. Prediction of ... | |
| Blast Induced Ground Vibration | 11/24/2011 |
| Q: I am right now researching about ground vibration effect to slope stability. As i know, ground ... A: Yes. Using the highest component of horizontal acceleration regardless of directionality is ... | |
| Blast Induced Ground Vibration | 11/23/2011 |
| Q: I am right now researching about ground vibration effect to slope stability. As i know, ground ... A: The action of ground vibration on slope stability is twofold. The vertical accelerations -- which ... | |
| grade rod | 11/6/2011 |
| Q: how to read a grade rod and turn the tenth to feet,and inches A: If you are thinking about the white telescoping fiberglass rods or a grade rod that is similarly ... | |
| foundations on rock | 10/26/2011 |
| Q: how would you advice on the construction on an outcrop of rock that has been blasted before for ... A: This is a very site-specific question. Here are some ideas for you to consider. Are the cracks ... | |
| converting 100s to inches | 10/22/2011 |
| Q: I'm setting some castings to grade but the stakes are in 100s how do I translate F-0 followed by 20 ... A: There are lots of different staking conventions but I think you are saying the stake reads something ... | |
| Effect of 2D analysis on displacement | 10/16/2011 |
| Q: I have almost same question as the last answered question by you. I am modelling several caverns in ... A: There is a fundamental text by Obert and Duvall on rock mechanics that gives many idealized stress ... | |
| Effect of 2D analysis on displacments | 10/5/2011 |
| Q: I would be grateful if you could help me with thisWhat are the effects of a 2D analysis ion ... A: For a hydrostatic or conventional lithostatic stress field, it depends on the dimensions of the ... | |
| Building house same time as creating landscape | 9/25/2011 |
| Q: I would like to if it is EASIER and LESS EXPENSIVE to build a new construction and create a ... A: Actually you build the foundation first and worry about the landscape later. Your idea is ... | |
| Rock blasting | 9/23/2011 |
| Q: Sir, We have to do surface mining 6o billion cubic meter rock excavations from hill available on the ... A: I wrote out a long answer to your followup and my ISP crashed before I could send it; I don't have ... | |
| Rock blasting | 9/19/2011 |
| Q: Sir, We have to do surface mining 6o billion cubic meter rock excavations from hill available on the ... A: 60 billion cubic meters? That is an absolutely immense quantity of excavation. Are you sure? ... | |
| Mechanical method of tunneling in hard rock | 9/16/2011 |
| Q: We have to construct twin highway tunnels in a sensitive location. The location become sensitive due ... A: Rock splitters and expansive grouts are options for rock breakage but when constructing an ... | |
| Vibrationless tunneling in hard rock | 9/16/2011 |
| Q: We have to construct twin highway tunnels in a sensitive location. The location become sensitive due ... A: I am not trying to be evasive but there is no method of making small granite fragments out of larger ... | |
| Pool excavation costs | 9/14/2011 |
| Q: We have just begun excavation on our pool and have been told that there will be an additional ... A: The explanation that comes to mind is that if the fill was not properly compacted it will not ... | |
| House foundation on expansive soils | 9/1/2011 |
| Q: We are getting ready to build a house.About six years ago we were going to build on this site and ... A: You are quite right to spend some money on proper geotechnical characterization and foundation ... | |
| basement footing on blasted limestone | 9/1/2011 |
| Q: We are considering blasting 4 ft deep in limestone for a basement. The blasting company said they ... A: The blasting company is referring to subdrill. This practice, which is nearly universal in ... | |
| Safe Distances from a Blasting Quarry | 8/23/2011 |
| Q: I'm in Fife, Scotland, and a local quarry has just had permission to start blasting for Dolerite. ... A: There is no "safe" distance because the effect on the surroundings depends on the design of each ... | |
| Fixing Sediment Fence to Rock | 8/8/2011 |
| Q: not sure if you can help me on this one, but your experience seems the most appropriate. I'm ... A: This is an unusual request because one normally does not install silt fence on rock, the rock being ... | |
| Hard rock | 8/2/2011 |
| Q: sir we are blasting with the running traffic road. therfore we can't do heavy blasting. in this ... A: From your question I understand that you are constrained by the presence of a nearby roadway and ... | |
| Exacvation of exploratory Adit in Rock | 6/16/2011 |
| Q: I want to estimate the proportion of cost for the cost of explosive used by the contractor who is to ... A: You would have to quantify the various cost centers for your specific project. Tunnel excavation ... | |
| Excavating Bedrock | 6/6/2011 |
| Q: My friend's home is pinned to bedrock (granite) and behind one small door in his basement is a small ... A: It depends entirely on the hardness and fracturing of the granite, and to a lesser extent on the ... | |
| Geotechnical engineering | 6/5/2011 |
| Q: Good evening Sir. I would like to know something about the creation of a square along a road on the ... A: Rock blasting is normally carried out by drilling vertical or steeply inclined holes. However there ... | |
| Estimation of Blasting tonnage before blasting , drill hole depth , spacing and quantity of explosive needed | 4/19/2011 |
| Q: Can you please educate me on how to estimate the tonnage of granite to expect before drilling. That ... A: When a blast hole detonates it tends to break outward and upward from the bottom. To assure that ... | |
| blasting vs mechanical breaking in urban area | 4/11/2011 |
| Q: We developed one product that uses air powered pump to split rocks. Can you please give me your idea ... A: An issue with compressed air breakers relative to other nonexplosive techniques such as expansive ... | |
| Road Construction | 3/22/2011 |
| Q: Can you please tell me the process of constructing a road? What does it involved? Are plans ... A: I have answered this question twice and see it is still pending. My previous answers were quite ... | |
| Admission to Post Graduate Course. | 3/17/2011 |
| Q: Sir, I have completed civil engineering and now I am looking ahead for a Master degree ... A: I answered this question once but I see it is still here so if you did not get my original answer I ... | |
| Impact of hydrolic hammering | 3/13/2011 |
| Q: Our city is replacing existing water/sewer lines. My house is aproximately 20-30 ft from where the ... A: Along with the videotape it is helpful to have written notes. The resolution on some videos can be ... | |
| Impact of hydrolic hammering | 3/11/2011 |
| Q: Our city is replacing existing water/sewer lines. My house is aproximately 20-30 ft from where the ... A: The vibration from a hoe-ram or hydraulic hammer depends on the size of the hammer. A large ... | |
| Blasting | 3/11/2011 |
| Q: What is the recommended maximum ppv for water wells? A: I don't know of any one recommendation. The limit of safe vibration in a water well depends on the ... | |
| Dispute in hard and soft cutting in road construction materials | 3/7/2011 |
| Q: Indeed with regards to your answer, I come along to confirm you that we are development agency like ... A: I thought the security issues you are facing included IEDs as well as direct attacks. The fact that ... | |
| Dispute in hard and soft cutting in road construction materials | 3/6/2011 |
| Q: We are managing road construction projects contracts in post-conflict conutry. Contracts are ... A: When I read your question the first thing I thought is if you are managing construction contracts ... | |
| Rock excavation | 3/1/2011 |
| Q: we are doing a trunk sewer project in a highly built up area with the trench passing on either side ... A: In this case you have a few choices -- drill the heck out of it and hammer the rock out, or drill ... | |
| Foundation on rock | 2/27/2011 |
| Q: We Thank you very much for your time to share your expertise with people like us. We will appreciate ... A: This is an excellent question and not something that comes up very often. The main issue is being ... | |
| Vibration control | 2/24/2011 |
| Q: I'm looking to bid a job on the Kaibab plataeu near Flagstaff, AZ; I'll need to drill\shoot a 52 ... A: I don't understand what you mean when you say there can be no vibrations extending down to 1500 ft ... | |
| cement | 2/1/2011 |
| Q: First, thank you for your time. The soil where I live is sandy to sandy loam. I am building a small ... A: If I understand you correctly, the material is essentially washdown residue from transit mix trucks. ... | |
| your kingston jamaica pier answer | 1/18/2011 |
| Q: I was reading your response to the question about piers in Kingston Jamaica. which I am going to ... A: Wind from tropical storms can be significant and you may not want to rely on topographic features; ... | |
| your kingston jamaica pier answer | 1/17/2011 |
| Q: I was reading your response to the question about piers in Kingston Jamaica. which I am going to ... A: I took a look at the drawing. I can address the pier design only. The depth of the pier bearing ... | |
| construction and drainage | 12/31/2010 |
| Q: I built a retaining wall 30' long by 6' high. I put 10-12" of gravel at the base with a sloped ... A: Lots of retaining walls with drains do not display any seepage from the drain holes. The purpose of ... | |
| dig a bacement under a slab house | 12/29/2010 |
| Q: I live in Florida and wan to dig a basement under my house. the house is built of wood it is L ... A: I have not done one of these before (I don't know anyone who has) but here are my thoughts. If ... | |
| Retaining Wall Backfill options | 11/27/2010 |
| Q: Mr. Cummings, I am building a retaining wall that is about 80' long and at it's lowest height is ... A: Normally walls are drained, as you seem to be aware. This is to limit overturning forces and to ... | |
| Water Well and Blasting | 11/24/2010 |
| Q: We were recently drilling a domestic well when we hit rock at about 150 feet that impeded progress. ... A: It sounds like your neighbor is looking for someone to pay the cost of fixing an ongoing problem ... | |
| retaining wall | 11/14/2010 |
| Q: Mr Cummings, I live in the Chicagoland area. Last July we had a large storm that flooded the lower ... A: Surely you have your reasons but I wonder why go to the trouble of making what was a garage door ... | |
| Building on a steep slope containing ledge | 11/10/2010 |
| Q: I have property which has a large somewhat flat area of ledge that then slopes down hill. The ... A: Building at grade is always less costly than excavating, but assuming you would have a basement ... | |
| price per square foot | 11/2/2010 |
| Q: What is the going rate for construction clean-up. I have an opportunity to clean a building. It will ... A: Costs for cleanup are calculated by estimating time and labor costs, plus whatever materials are ... | |
| expansive motar powder | 10/29/2010 |
| Q: how to manufacture expansive motar powder for fracturing rock and cement ? A: Commercial grouts are offered under various trade names -- Dexpan, Daigh Chemical, Bustar, Bristar, ... | |
| dirt/concrete | 10/23/2010 |
| Q: First, thank you for your time. I am building a large pond, the surface area about 29,000 sq ... A: None of the methods will make your soil actually waterproof but the addition of fine material will ... | |
| Rock Anchor Foundation Shear Friction & Lateral Resistance Issue | 10/6/2010 |
| Q: Robert, I am designing a winch foundation with rock anchor implementation, refer to figure 1 in the ... A: I thought I answered this but it remains in my queue so here is what I remember of my original ... | |
| split large rock dexpan? | 10/6/2010 |
| Q: I have large rock which i want to split.(2.5 feet high 4 feet wide and sticking out of bank 3 feet. ... A: Dexpan will work but so will a hydraulic splitter. If you are drilling 1.5 in. diameter holes (you ... | |
| blasting damage | 10/4/2010 |
| Q: In 2006, there was blasting done to create a new super hwy, blasting through 230 ft of mountain, ... A: I'm having trouble understanding the particulars of your case, especially the units of measure. ... | |
| granite quarry | 9/2/2010 |
| Q: i want to setup a granite quarry and im having trouble calculating the amount of rock in tons ... A: You need a tonnage factor to convert from colume to weight, but first the volume. First you need to ... | |
| Drainage in bedrock | 9/2/2010 |
| Q: Our home is build on a sandstone bedrock. The land slopes towards the back. we recently built onto ... A: The drain sounds like it is built correctly so it does not sound like the water ingress problem can ... | |
| Drainage in bedrock | 9/1/2010 |
| Q: Our home is build on a sandstone bedrock. The land slopes towards the back. we recently built onto ... A: Trying to understand the physical layout here. You are saying the slope is down toward the rear and ... | |
| Footings for Elevated Deck | 8/21/2010 |
| Q: Mr. Cummings, We are having our deck rebuilt by a contractor at our cabin near Taos, NM. It is an ... A: It is not necessary to replace the footings (concrete piers). You can drill through them into the ... | |
| Rock Blasting Costs | 8/9/2010 |
| Q: From your experience what would be the guestimate costs (ballpark)to blast 4-6 feet down for a ... A: The cost can vary widely depending on the part of the country you are in, site conditions, access, ... | |
| Design live load of concret floor in 3 story building | 7/6/2010 |
| Q: I am trying to figure out if we are storing to much material on the second floor of our building. ... A: The live load capacity relates to different characteristics of loading. Generally the governing ... | |
| Design live load of concret floor in 3 story building | 6/30/2010 |
| Q: I am trying to figure out if we are storing to much material on the second floor of our building. ... A: There is a difference between live and dead loads. Dead loads are loads that do not change, which ... | |
| Possible structural damages post blasting | 6/24/2010 |
| Q: I have a concrete pool that is 16 years old. Prior to the blasting of rock across the street (to ... A: 100m seems very close as a preblast survey range. For residential blasting, 300 ft is about the ... | |
| Blasting for a New Development | 6/22/2010 |
| Q: A new neighborhood is being developed adjacent to my development (home is 3 yrs old). To complete ... A: Modern blasting is performed using millisecond delays. What this means is that each blasting event ... | |
| Vibration Monitoring | 6/22/2010 |
| Q: I am working on a construction project in NY. Part of our scope is to demolish concrete and rock on ... A: The acceleration reported by a blasting seismograph that triggers on ppv is, as I think you know, ... | |
| anchoring concrete piers on bedrock | 6/8/2010 |
| Q: Good Morning, I will be constructing a cottage on an island north of Kingston and am wondering how ... A: Too bad it's not in Jamaica. I was about to offer to come out there and design the piers for you, ... | |
| anchoring concrete piers on bedrock | 6/8/2010 |
| Q: Good Morning, I will be constructing a cottage on an island north of Kingston and am wondering how ... A: I take it by inference that your site location is near Kingston, Jamaica (as opposed to Kingston ... | |
| Rock blasting in road construction | 6/7/2010 |
| Q: Good evening Sir. I am a project manager for I'M high standard road construction in Nigeria.My road ... A: Subdrill is almost always required unless the pattern is tight and the rock is tightly laminated ... | |
| Jack and Bore | 6/7/2010 |
| Q: We have a project with btwn 6-10 jack and bore locations. The area has sandy soils. The J%26B pits ... A: If I understand your question, and I am not sure I do, how can you be sure the pit water ... | |
| house foundation | 6/6/2010 |
| Q: I have 3 year old home and one end of house is dropping. No water leaks in foundation, house drains ... A: Blast-induced settlements, per se, are not really that common. The most likely causes are "quick" ... | |
| Footing on shot rock | 6/4/2010 |
| Q: Cummings, We have just had rock blasted for the foundation of our house. Unfortunately, the rock ... A: It really depends on the durability of the rock. It is unlikely that the shot rock will settle over ... | |
| Blasting - PPV - 2 | 5/22/2010 |
| Q: What factors would influence the PPV's to have a lower reading the closer their proximity to the ... A: Yes, you can safely assume that seismographs placed a few meters away from the blast source on the ... | |
| Blasting - PPV | 5/21/2010 |
| Q: What factors would influence the PPV's to have a lower reading the closer their proximity to the ... A: All other things being equal, the peak particle velocity must decrease with distance from the source ... | |
| Foundation in Blasted Rock | 5/2/2010 |
| Q: Mr. Cummings, I apologize if you've answered this question in previous posts; I went through many ... A: Unless there is some reason to believe that controlled blasting of the limestone will not be ... | |
| Blasting records | 4/30/2010 |
| Q: Do you review blasting records? A: Yes -- a lot. Blasters are required to keep an explosives inventory, which is part of it. Most ... | |
| Securing rebar into rock for pier supports | 4/22/2010 |
| Q: Robert, I read your advice to the person that was going to pour a footing on bare rock. My question ... A: The Sackrete anchor cement will probably do but if you can find it, there are anchoring grouts from ... | |
| Load capacities of concrete | 4/20/2010 |
| Q: I have a property with 25yr. old cement stabilized limestone base appox 4" thick it's very hard . ... A: 50-150 tons is a wide range, so it's hard to say, except that you would of course figure on 150 ... | |
| Securing rebar into rock for pier supports | 4/14/2010 |
| Q: Robert, I read your advice to the person that was going to pour a footing on bare rock. My question ... A: First off, I don't think you lack brain matter for having a cabin there. I worked in SE Alaska ... | |
| Creating a Cave | 4/5/2010 |
| Q: I'm a design uni student doing a project on creating a cave as a public space. I was wondering how ... A: The square steel plates are indeed rock bolts, probably at least 10 ft long (they are seldom less ... | |
| Creating a Cave | 4/4/2010 |
| Q: I'm a design uni student doing a project on creating a cave as a public space. I was wondering how ... A: First of all, good on you for taking on such an interesting project! What an idea. You probably ... | |
| Geological Engineering PE | 3/25/2010 |
| Q: My girlfriend just graduated with a BS in Geological Engineering and she's now trying to get through ... A: The company is Saguaro GeoServices, www.saguarogeo.com There are services available to get remedial ... | |
| Geological Engineering PE | 3/14/2010 |
| Q: My girlfriend just graduated with a BS in Geological Engineering and she's now trying to get through ... A: I sympathize. When I took the FE it was a national exam that was the same for all engineering ... | |
| Ground vibration through ledge. | 3/8/2010 |
| Q: I am curious about the ground vibration effects through shallow ledge. Specifically, a contractor ... A: I have been traveling and not able to receive email. My apologies for not getting back to you ... | |
| Pipeline Construction Blasting | 3/2/2010 |
| Q: I have worked in pipeline construction for about 25 years in every area but blasting in rock areas ... A: The best advice I can give you would be to go on www.isee.org and purchase a copy of the Blaster's ... | |
| Building a Root Celler | 2/28/2010 |
| Q: We are new at the root cellar idea. We have a home built on flat ground but then gently slopes down ... A: You didn't actually ask a question but I get the idea that perhaps you don't know where to start. ... | |
| Trenching in Pennsylvania | 2/27/2010 |
| Q: I am trying to make the best machine selection for this job. The rock is extremely hard in certain ... A: If it's several miles long you should consider blasting wherever access and surrounding land used ... | |
| Suppliers | 2/16/2010 |
| Q: Hey so I am doing a proposal on the importance of having separate systems for sewers and drainage. I ... A: You need installed prices, not material prices, so calling pipeline suppliers (national or regional) ... | |
| basement flooding | 2/1/2010 |
| Q: We blasted for our basement in 1997. We have a 2000 sq ft.ranch. The first time our basement ... A: Blasting will not disrupt the water table. What can happen is that blasting can widen fractures, ... | |
| follow-up question on open cast mining | 1/29/2010 |
| Q: I wondered if you would be kind enough to answer some more questions as we had a meeting with ... A: First let's discuss ground vibrations, then we'll get to airblast overpressure. Blast vibration ... | |
| lake draining | 1/27/2010 |
| Q: We own a house on a hill overlooking a lake. Scottish Coal has been operating an open cast mine ... A: I am not sure what jurisdiction you are in so I cannot opine on the activities of oversight agencies ... | |
| Career Schooling | 1/13/2010 |
| Q: Cummings, My step-dad is operating a small crew boat on the Columbia River for a company that ... A: My background is in geological engineering (Bachelor's and Master's) which is helpful if you want to ... | |
| Trenching in rock | 1/3/2010 |
| Q: I am seeking information regarding an equipment or methods of excavating a water main trench, ... A: I take it you have concluded that the rock can be excavated with a trenching machine. Hopefully you ... | |
| rock blasting | 12/12/2009 |
| Q: Good day to you. Sir, I once saw a TV show where a man showed the difference between a rock that was ... A: I don't know of the show you saw (wish I did). A charge placed internally within a rock first ... | |
| rock blasting | 12/3/2009 |
| Q: How will blasting affect different types of foundations. I mean to what extent will its damage be ... A: That's a very broad question. It sounds suspiciously like a homework question because it is so ... | |
| fence post in ledge | 11/22/2009 |
| Q: I am installing a 5' high chain link fence in ledge. What machinery would you recommend? The job ... A: First please excuse the late response. I have been traveling due to work and holidays and could not ... | |
| Concrete Load Bearing | 11/11/2009 |
| Q: I am remodeling a 30 years old 2 storey condo. The entire structure is reinforced concrete and the ... A: My opinion after looking at the floor plans is that the kitchen wall running the long way probably ... | |
| Load bearing concrete floor | 11/8/2009 |
| Q: What would the thickness of the concrete floor have to be to sustain forklift traffic tare 4000kg + ... A: Floor slabs on grade should be analyzed for adequate structural live loads. Since floor slabs maybe ... | |
| Concrete Load Bearing | 11/8/2009 |
| Q: I am remodeling a 30 years old 2 storey condo. The entire structure is reinforced concrete and the ... A: I have tried to diagram the floor plans of the first and second stories to see what rooms and walls ... | |
| Concrete loading | 11/2/2009 |
| Q: Even though concrete is given (for example) a 3500 psi load rating, where does the thickness become ... A: The strength of concrete is measured in uniaxial compression on either a 4x8 right cylinder (small ... | |
| blasting and damaging vibrations | 10/28/2009 |
| Q: i have been issued a stop work order because i have exceeded 2" PPV on my monitor which has been ... A: A stop work order is pretty serious. Utilities continue to mis-apply conventional vibration ... | |
| Fordham Gneiss | 10/5/2009 |
| Q: We may need to remove up to 250 CY of Fordham Gneiss in Westchester county, NY. What kind of ... A: I can't give you many specifics without knowing how the rock is situated. If it is in a confined ... | |
| effect of dynamite on tree roots | 9/30/2009 |
| Q: For a recent sewer installation, the contractor dynamited (through subterranean ledge) from the road ... A: Odd that blasting had to be used for a septic tank site. One would think that rock requiring ... | |
| rock excavation | 9/23/2009 |
| Q: We are placing vault toilets which shall require 4-6 inches (in depth) of lime coral rock removal to ... A: This is very uncertain because it depends on the hardness of the lime coral rock and whether it is ... | |
| clinker | 9/15/2009 |
| Q: "I am studying the frequency distribution of size of crystals in a cement clinker. As a clinker is ... A: The cooling rates of igneous rocks vary widely and the formation of crystals has not only to do with ... | |
| Concrete slab over root cellar | 8/23/2009 |
| Q: Mr. Cummings, I have an 8'x12' root cellar with concrete walls. Will a 6" thick slab roof with #4 ... A: All three, actually. The standard details for a reinforced concrete box culvert for the Colorado ... | |
| Concrete slab over root cellar | 8/22/2009 |
| Q: Mr. Cummings, I have an 8'x12' root cellar with concrete walls. Will a 6" thick slab roof with #4 ... A: I'm not a structural engineer but I think a single mat of #4 on 2 ft centers sounds just a little ... | |
| HORIZONTAL REBAR IN FOOTINGS | 8/14/2009 |
| Q: BUILDING A NEW HOUSE IN NC. Residential code in NC does not call for rebar in footings. In ... A: I have not done a survey nationwide of footing construction so I can't say how common it is to omit ... | |
| concrete footings O.K.? | 8/14/2009 |
| Q: We recently poured some concrete spread footings for a new house. Footings were 10" thick and 24" ... A: The concrete should have attained its initial cure and set long before (24 hrs) you had weather ... | |
| compaction of fill | 8/13/2009 |
| Q: I'm in the initial stages of building a 42 x 48' shop, currently having a contractor do the dirtwork ... A: Somebody should be testing your fill compaction to eliminate all this guesswork -- you are spending ... | |
| Vibration Limits and Human Perception | 8/12/2009 |
| Q: Good Afternoon, I work for a regulatory agency that looks after medium scale surface quarries. We ... A: This is a huge topic and I could go on and on but I will try to give you a concise answer, which ... | |
| soil compaction testing for pool construction | 8/4/2009 |
| Q: We are in the process of having a pool built by a contractor. The city required us to review the ... A: OK, from soup to nuts, here is what I think. You stated that the original soil investigation report ... | |
| redoing concrete pilings under pool deck | 7/15/2009 |
| Q: I live in the northeast and had a gunite pool build into the 45 degree slope of my back woods in ... A: First, this is a complex geotechnical question and the requirements for drilled shaft diameter, ... | |
| Underground walkway specifications | 7/11/2009 |
| Q: Is there any relatively simply way (or formula that could be used) to determine the needed ... A: In order to get an idea of what will be required, my suggestion would be to get a hold of a standard ... | |
| Concrete footings for a playhouse | 6/30/2009 |
| Q: I am building a treehouse using 4-8x8x14' either pine or cedar vertical beams 10' apart with a metal ... A: If this were a more critical structure you would need to perform a bearing capacity analysis for the ... | |
| Concrete slab strength/design load | 6/22/2009 |
| Q: Mr. Cummings, I'm trying to determine if a concrete floor slab will support a 80000 lb steel block ... A: You're right, 760 psf is not much load, considering presumptive bearing pressures for spread ... | |
| Concrete slab strength/design load | 6/22/2009 |
| Q: Mr. Cummings, I'm trying to determine if a concrete floor slab will support a 80000 lb steel block ... A: The 3,000 psi as you described it would be the minimum allowable compressive strength of cylinders ... | |
| Lake Limestone Retaining Walls | 6/22/2009 |
| Q: Our lake has many homes building giant flat stone limestone retaining walls. They are bowed in my ... A: Stacked-rock retaining walls are commonly built to nominal heights (say, no more than 3 times the ... | |
| Concrete slab strength/design load | 6/12/2009 |
| Q: Mr. Cummings, I'm trying to determine if a concrete floor slab will support a 80000 lb steel block ... A: Please excuse me for not responding sooner. I just returned from my first vacation in several ... | |
| Concrete Structural loading | 6/8/2009 |
| Q: I a have a mezzanine to install on a concrete floor: Slab is 7" thick, 25mpa with 10m rebar on 18" ... A: Please excuse me for not responding sooner. I just returned from my first vacation in several ... | |
| linker rod | 6/8/2009 |
| Q: sir i need to know how to READ the linker rod thank you A: I could try to describe this to you but a picture is worth a thousand words -- try the link below; ... | |
| anchoring | 6/5/2009 |
| Q: Can you recommend a name brand adhesive/hydraulic cement...available at Home Depot or Lowes that ... A: Use por-rock if you can get it. Also there is a product called (I think) Anchor-Lock, comes in a ... | |
| slope vs. percent of grade | 5/31/2009 |
| Q: Mr Cummings, I understand % of grade as rise over run, but slope derivied from contours ... A: In the US, cut slopes are commonly given in H:V. Therefore a 1/2:1 slope is quite steep (horizontal ... | |
| Rock Excavating | 5/23/2009 |
| Q: My excavating/foundation contractor made it known in his contract that rock excavation would be ... A: Actually, I don't know what size excavator and hoe-ram he is using but $1500/day isn't bad. A large ... | |
| Dam Construction | 5/20/2009 |
| Q: I wonder if you may know who are the main construction contractors in the US or Canada that are ... A: Most major earthmoving and general contractors have involvement in dam projects of various sizes. ... | |
| Removing Bedrock from Backyard | 5/12/2009 |
| Q: Our house has bedrock in the backyard with a fairly steep incline. It takes up majority of the ... A: This all depends on the structural fabric of the rock. In most cases the rock can be removed ... | |
| concerns over a propose granite quarry nearby | 5/11/2009 |
| Q: I would like to know what kind of effects blasting at a proposed granite quarry will have on my ... A: Trees and intervening topography will help with some of the airblast overpressure but the main pulse ... | |
| concerns over a propose granite quarry nearby | 5/10/2009 |
| Q: I would like to know what kind of effects blasting at a proposed granite quarry will have on my ... A: The fact that you are aware of the frequency dependence on vibration response indicates that you ... | |
| construction of house foundation on exposed rock slope | 5/4/2009 |
| Q: I've read some of your previous answers and I would be grateful to your response to this question. ... A: The limestone should not be moving (if it is actively moving you are in a slide area and should not ... | |
| construction of house foundation on exposed rock slope | 5/1/2009 |
| Q: I've read some of your previous answers and I would be grateful to your response to this question. ... A: I doubt you will encounter unweathered limestone at the depths of interest. The idea is to minimize ... | |
| construction of house foundation on exposed rock slope | 4/30/2009 |
| Q: I've read some of your previous answers and I would be grateful to your response to this question. ... A: Good quality, sound crushed stone should not slide on a slope whose inclination is less than 20 ... | |
| determining the mesurements on a surveys range pool | 4/16/2009 |
| Q: Trying to get information on how to read the elevations on the surveyors range pole in Ft, In, Hun. A: Most range poles are graduated in hundredths of a foot -- which is about an eighth of an inch. ... | |
| building a deck on bedrock | 4/3/2009 |
| Q: I am planning to build a series of decks/stairs on exposed limestone bedrock and would appreciate ... A: The number of anchors depends on the total amount of resistance needed. Using 10-12 inch sonotubes ... | |
| building a deck on bedrock | 4/2/2009 |
| Q: I am planning to build a series of decks/stairs on exposed limestone bedrock and would appreciate ... A: My opinion is that you are on the right track -- anchor concrete footings to the rock surface, and ... | |
| grantie outcropping | 4/2/2009 |
| Q: We would like to build a small cottage with a basement on a lot that has a large 20x20 granite ... A: If I understand your question (a way to measure the depth of the rock), the rock that exists at the ... | |
| the blasting work in Turkey | 3/29/2009 |
| Q: I got a contract in Iskenderan Turkey including rock blast work of quantity 70,000m3, and want to ... A: You have a contract with no price for blasting? Lucky you. Even in the United States I could not ... | |
| Rock Excavation | 3/23/2009 |
| Q: I am doing a project in Bayonne NJ in extremely hard rock and a 80,000 lb excvator with a 10,000 lb ... A: Obviously you should consider blasting, but I'm guessing that site conditions may be making you ... | |
| Backfilling using wet soil | 3/9/2009 |
| Q: Recently I installed/rebuilt a landscaping drain system. The system consisted of a 12" dia and a 15" ... A: 15 inch culvert pipe -- quite a drain system for a landscaping project! You didn't say how wet the ... | |
| online grade checking exercises | 12/16/2008 |
| Q: i have been searching the net for any online grade checking exercises to practice setting slopes and ... A: Good on you for committing to learn this. I have worked with a lot of equipment operators who don't ... | |
| Anchoring into rock for a big (16 foot swinging gate) | 12/15/2008 |
| Q: I'm wanting to install a swinging (16')steel gate across my cottage lane in Newfoundland. There is ... A: The unsupported vertical loads for a swinging steel gate 16 ft wide are significant and would ... | |
| Trenching charges | 12/2/2008 |
| Q: Our electrical company is a small one and we have a ditch witch. We are starting on a large project ... A: In this case I would try to negotiate an hourly rate because you cannot predict the state of frost ... | |
| rock foundation and house | 12/2/2008 |
| Q: Robert: I read an answer you gave in 2005 about rock foundations “As an aside I don't know why ... A: There are dozens of references on foundations and soil mechanics, one of the best being by Bowles, ... | |
| pan deck construction | 11/22/2008 |
| Q: I'm trying to learn more about pan decks for a residential garage on a sloped lot. Is this a common ... A: If I understand you right, you think perhaps the use of pan decking rather than another floor method ... | |
| rock blasting and our well | 11/14/2008 |
| Q: We live in a rural area on 16 acres of a very rocky hillside. Our neighbours have blasted an ... A: It would be highly unusual, if not impossible, for blasting to cause a well to "run dry" that was ... | |
| fence poles in lava rock | 11/13/2008 |
| Q: only thing is that the property is in Hawaii and it is on the slope of a volcano so I need a easy ... A: First of all I wonder why it takes 200 holes to fence a 1/2 acre lot with chain link. According to ... | |
| rock/cement covering inside house | 10/14/2008 |
| Q: My house was built about 30 years ago on rock. There is a room inside my house that has cement ... A: By cement I presume you mean concrete, although it really does not matter. The answer is yes, you ... | |
| trencing with boulder buster | 10/1/2008 |
| Q: Good day Mnr. Cummings the Boulder Buster works wonders with loose boulders,but i need to blast a ... A: When you say 1.5 meter trench I assume you are talking about the depth, not the width because you ... | |
| concrete porch | 9/21/2008 |
| Q: We would like to add a layer of concrete to an existing porch. The structure is in good condition. ... A: Do not add new concrete unless the surface it is to bond to is clean concrete and treated with a ... | |
| Retaining wall | 9/20/2008 |
| Q: My house is on a slope and was built 40 years ago. We moved in 10 years ago, and the concrete ... A: It gives me a much better idea of what you are dealing with. Apparently, the retaining wall must ... | |
| ledge blasting | 9/20/2008 |
| Q: is it possible to break up ledge using a high pressure water jet rather than explosive charges ? A: That all depends on the hardness of the rock, the prevalence of fracturing, and the intensity of the ... | |
| Groundwater control | 9/12/2008 |
| Q: The site in Anacorets WA has a pit where shallow , seasonal, groundwater stands at a depth of ... A: You may be misinterpreting the geotechnical recommendations. My guess is that the sheet piling was ... | |
| method to dig and break rocks with excavator | 9/1/2008 |
| Q: I'm looking for some method to dig and break rocks with excavator.Do you have some knowledge of this ... A: Depending on the size of the excacvator, there are attachments that will either break rocks directly ... | |
| excavating and backfilling | 8/30/2008 |
| Q: I am contemplating putting an addition onto my home using a cargo shipping container (20'X8'X8.5'). ... A: Most wet sand-silt-gravel mixes will weigh in the neighborhood of 135 pcf if compacted and 125 pcf ... | |
| Vibration Monitoring | 8/28/2008 |
| Q: I am an Environmental Officer working for construction company and responsible for vibration ... A: I can see why you are confused about the vibration specification. From what you sent it looks like ... | |
| Retaining wall | 8/24/2008 |
| Q: My house is on a slope and was built 40 years ago. We moved in 10 years ago, and the concrete ... A: I don't know that I have ever heard of a wooden retaining wall. I am familiar with soldier pile ... | |
| Rock Removal | 8/20/2008 |
| Q: I have a 12' x 4' rock sticking up about 2' above the ground exactly where I want to put a shed. How ... A: Breaking rock always involves the input of energy sufficient to overcome whatever bonds are holding ... | |
| foundation on piles | 8/13/2008 |
| Q: just came across this board, thanks a lot for sharing your expertise on here! Your background ... A: The pile estimate was from Means' Heavy Construction 2008. Residential construction may be slightly ... | |
| foundation on piles | 8/12/2008 |
| Q: just came across this board, thanks a lot for sharing your expertise on here! Your background ... A: I understand your quandary. You have a price point and want to know if the site improvements will ... | |
| basement under garage | 8/11/2008 |
| Q: Planning to build a log 34 x 36 3 bay garage with 2nd floor. Foundation planned to be cement slab. ... A: It depends in part on the basement foundation but yes, in general, you can park autos on a suspended ... | |
| Drawing Elevation | 8/6/2008 |
| Q: How do you determine the difference in elevations from a drawings and then convert that number to ... A: Depends on what the elevation units are to begin with. If the elevations are already in feet, it's ... | |
| Underground blasting within 25' of my home! | 8/5/2008 |
| Q: As part of an upgrade to it's sewer system, the city of Baltimore will be tunneling beneath the ... A: You should have blasting seismographs placed at your home, and monitored in accordance with the ... | |
| Environmental Concerns - New Construction | 8/4/2008 |
| Q: The adjoining property has been sold to a builder, and they are planning to build seven large homes, ... A: Spread foundations are dug out. If the homes have suspended floors they may partially be founded on ... | |
| Drilling into Rock - Massachusetts | 7/28/2008 |
| Q: I have dug out holes for footings for a deck. I have hit ledge on almost every hole after digging ... A: 20 minutes and 1/4 inch, huh? You should be doing better than that. Did it toast the bit? It ... | |
| water well | 7/26/2008 |
| Q: I purchased this newly constructed home in March of 2004. Everything was checked and certified, ... A: You're welcome. I would be curious to know what they find. If the well is 175 ft and the static ... | |
| water well | 7/25/2008 |
| Q: I purchased this newly constructed home in March of 2004. Everything was checked and certified, ... A: The water table would not drop in 2 days especially if the aquifer was prolific to start with, ... | |
| water well | 7/25/2008 |
| Q: I purchased this newly constructed home in March of 2004. Everything was checked and certified, ... A: Sorry to hear about this. Being out of water is a pain. First of all, you might as well contact ... | |
| Basement wall bulging | 7/19/2008 |
| Q: Good morning Mr. Cummings. I have a home that was built in 1969. At the front of the house, the ... A: You didn't conclude with a question but I bet you wanted to know if all this sounds reasonable, and ... | |
| mountain lot foundation | 7/16/2008 |
| Q: I own the top of a mountain that adjoins Old Rag Mountain in the Shenandoah National Park. The road ... A: From a geotechnical standpoint, the erosion of the highway has little to do with your structure ... | |
| breaking rock | 7/11/2008 |
| Q: My house sit on top of a rock cap which I am thinking of blasting to increase the height in the ... A: General guidance is to make the hole burden not more than 10 times the hole diameter, and start with ... | |
| effects of blasting on preserved wood foundation | 7/7/2008 |
| Q: What could be the potential effects of upslope (approx 500ft from house) highway-type rock and bluff ... A: This is about the third time I have put together a reply and sent it through but had AllExperts drop ... | |
| Building a House on Moist Ground | 7/7/2008 |
| Q: We live in Middle TN, with lots of rock just under the soil. We own two adjacent lots: one has our ... A: In general, yes, you can bring in fill to raise the grade and make building a house feasible. ... | |
| rock excavation | 6/30/2008 |
| Q: Could you suggest some references comparing various rock excavation techniques (blasting, mechanical ... A: A great question. Until you brought it up, it had never occurred to me that I know of no single ... | |
| french drain weeping tile in bedrock | 6/30/2008 |
| Q: We excavated our hole for our home to be built on a 8" high footing and a 24" stem wall. The bottom ... A: Why would the pipe have to be perforated under the driveway? It sounds like you need just to just ... | |
| poured wall foundation on rock | 6/27/2008 |
| Q: As a follow-up question to the answer you gave gave last year (06/07): I have property that is on a ... A: I answered this question right after it was posted but the site says it is pending. I have asked ... | |
| effects of blasting on preserved wood foundation | 6/25/2008 |
| Q: What could be the potential effects of upslope (approx 500ft from house) highway-type rock and bluff ... A: Is the blasting occurring above or below you? Is the blasting progressing toward or away from your ... | |
| proper depth for footings; caliche layer | 6/23/2008 |
| Q: Help, please! I live in the Phoenix, Arizona area and would like to construct a 10' high trellis ... A: I answered this question right after it was posted but the site says it is pending. I have asked ... | |
| survey stakes | 6/15/2008 |
| Q: m shure the will survay the points for them but i need to read the stakes i think can you help me A: You need to get with the surveyor and see how he puts the cut stake information on. Different ... | |
| Basement walls and slab failure | 6/10/2008 |
| Q: I have a home in upstate NY where I have two problems. The first is that it appears as if the ... A: If the cracking in the walls is in fact settlement rather than a response to active earth pressures ... | |
| Slotted/ Bored Piers | 6/10/2008 |
| Q: I am building my first home and have been advised by my builder that they had to do these bored ... A: One would ordinarily not switch from a shallow spread foundation to a pier foundation just because ... | |
| Driveway poured while raining | 6/4/2008 |
| Q: On Tuesday, May 27, we had approximately 50 yards of concrete poured to provide a 4" dirvieway ... A: When concrete is finished, the surface is worked repeatedly which causes the aggregate to ... | |
| Driveway poured while raining | 5/31/2008 |
| Q: On Tuesday, May 27, we had approximately 50 yards of concrete poured to provide a 4" dirvieway ... A: In my opinion it was a mistake to go ahead and pour. A concrete contractor should be used to ... | |
| steep slopes | 5/30/2008 |
| Q: how can i measure the steep slops % on the property. is there a simple way A: The % slope is the vertical slope change divided over the horizontal distance over which that change ... | |
| Post holes | 5/27/2008 |
| Q: I have a stockade privacy fence that had 3 sections fall over, posts and all. In looking in the post ... A: Wow. Must be some really hard rock if jackhammers and a rotary hammer drill with a carbide tipped ... | |
| Concrete Load | 5/26/2008 |
| Q: I was wondering what the max load for concrete is? I have a shop with 12in thick concrete and want ... A: The capacities of concrete slabs-on-grade are matters for a structural engineer to consider, and ... | |
| PPV (in/s) to G? | 5/22/2008 |
| Q: I'm a project manager with a heavy construction firm, and we've been blasting rock for about a month ... A: Acceleration (g) is related to the particle velocity in inches per second (ips) through the ... | |
| (107) shafts excavation | 5/21/2008 |
| Q: There is a requirement to dig 110 holes in the ground about 500 meters apart.Each between 8-10 ... A: This is a huge question and well beyond this forum. I will try to give you some ideas but this is ... | |
| Slope Creep | 5/17/2008 |
| Q: It seems like our whole street (which is on top of a hill) is having problems with the retaining ... A: Unless soil liquefaction or earthquake motions are the reason (I don't recall hearing of any major ... | |
| We hit rock when digging our pool | 5/16/2008 |
| Q: Mr. Cummings - I need your advice!!! We began digging our pool yesterday and hit rock about 2-3 ... A: I have a few questions before I can give you an answer. First, how much rock remains to be removed ... | |
| concrete post footing on rock | 5/13/2008 |
| Q: So it seems the perfect little spot for my two story 16x24 cabin is on a 4:1 slope and has solid ... A: You didn't say what the spacing of these pier foundations would be, or the type of construction, ... | |
| SIMOPS Diving & underwater D&B | 4/24/2008 |
| Q: What is the safe distance for a diver/swimmer to be in the water while conducting underwater D&B? ... A: OK, in that case, a general rule of thumb would be around 1000 ft. for charges of 30 lb or so. ... | |
| Soil Nails | 4/22/2008 |
| Q: I have had varying advice about the placement of soil nails on my landslide. Two consultants said ... A: There are no set standards for nail coverage. The design requirements for soil nails are dependent ... | |
| Pavers over Aggregate? | 4/17/2008 |
| Q: I have small porch/stoop (6x8 or so) that is covered in exposed aggregate. Leading up to the stoop ... A: I don't know anyone who has a brick stoop although if the pavers were set in concrete I don't know ... | |
| marl road | 4/17/2008 |
| Q: Mr. Cummings, I live on a private road, a marl road, the maintenance of which is shared by myself, ... A: I agree, especially if the subgrade is clayey which I bet it is, given your description. However ... | |
| Roadway Defect Expertise | 4/16/2008 |
| Q: I had an accident driving my Harley on a highway after dark as a result of gaps in the road surface ... A: Actually, I don't litigate in these areas so don't have the contacts you are seeking. You should ... | |
| Roadway Defect Expertise | 4/13/2008 |
| Q: I had an accident driving my Harley on a highway after dark as a result of gaps in the road surface ... A: Probably busted up the Harley, too. Sorry to hear about that. What a bummer. You didn't say what ... | |
| Excavator for use in Rock Blasting | 4/7/2008 |
| Q: I have read your answers and find them very helpful. I am using a blasting company to break around ... A: I answered your question the day it was posted, but I have just been informed that the system dumped ... | |
| Concrete block wall | 4/2/2008 |
| Q: I want to build a concrete block wall that will be have cultured stone affixed to the one side of ... A: If you are backfilling against the wall that makes it a retaining wall. Hopefully you are designing ... | |
| Retaining Wall Failing | 3/24/2008 |
| Q: Mr. Cummings thank you for the additional information on the Slope Creep issue. You have helped me ... A: I think you are on the right track. I hope 4 ft will be enough but even that would be an ... | |
| Dir. Horizontal Boring - Test data required? | 3/20/2008 |
| Q: We, a state DOT, need to install about 700' of utility pipes by primarily subsurface methods. We've ... A: I think it kind of depends on where you are and what geotechnical conditions are extant. If for ... | |
| retaining wall failing | 3/20/2008 |
| Q: I have begun to weigh the different options to determine how to deal effectively with the "slope ... A: One thing to keep in mind when considering a supplemental footing and piers is that you are adding ... | |
| interceptor drain to dewater unstable slope | 3/4/2008 |
| Q: Behind my house I have a 1:1 slope which since the loss of three large oak trees from the top of the ... A: The intent of the intercept would be to remove infiltration before it becomes ground water. You are ... | |
| interceptor drain to dewater unstable slope | 2/29/2008 |
| Q: Behind my house I have a 1:1 slope which since the loss of three large oak trees from the top of the ... A: I have been considering this, especially the part about the shallow (5 ft) ground water table. The ... | |
| interceptor drain to dewater unstable slope | 2/29/2008 |
| Q: Behind my house I have a 1:1 slope which since the loss of three large oak trees from the top of the ... A: Because your crawl space is dry, this sounds more like an erosion problem than a geotechnical slope ... | |
| Retaining Wall Failing | 2/23/2008 |
| Q: Mr. Cummings: This is a followup to the 48'x24' retaining wall failing post on February 19. I will ... A: I answered the followup right after you posted it and apparently that answer was lost. Aorry. I ... | |
| Retaining Wall Failing | 2/19/2008 |
| Q: I have a 48' x 24' detached two car garage on a slope. It has a concrete slab and the slab is not ... A: I suspect that this is mostly a drainage-induced bearing capacity or settlement problem but need a ... | |
| Vibration Blast Monitoring | 2/19/2008 |
| Q: scaled distance of 100 to .." Your response was excellent! Do you bury the triaxial seismic geophone ... A: If the geophone is vibrating in resonance with the incoming ground motion then a prolonged exposure ... | |
| Vibration Blast Monitoring | 2/18/2008 |
| Q: scaled distance of 100 to .." Your response was excellent! Do you bury the triaxial seismic geophone ... A: Some pracitioners bury the seismograph sensor which is hard to argue with, but I question the need ... | |
| big rock encountered when digging a pool | 2/10/2008 |
| Q: Mr. Cummings, Our pool contractor hit a rock that is approximately the size of a rhinoceros. Should ... A: I am not sure what the difference is between your hoe-ram designations. If 500, 750, and 1500 are ... | |
| Rock Excavation | 1/22/2008 |
| Q: Job Info: Norther NJ job site very tight site and well populated. The rock is Basalt very dense ... A: That's the first time i have heard of the swiss cheese method not working. Sometimes the ... | |
| Rock Excavation | 1/20/2008 |
| Q: Job Info: Norther NJ job site very tight site and well populated. The rock is Basalt very dense ... A: I think you have the right idea, but my first reaction is, if you can bring in a drill for 2 inch ... | |
| pool rock | 1/18/2008 |
| Q: Mr. Cummings, Is the expansive grout something I could find at a local hardware store? Is it ... A: I doubt you can find this specialty material at ordinary retail stores. The yhave trade names like ... | |
| big rock encountered when digging a pool | 1/18/2008 |
| Q: Mr. Cummings, Our pool contractor hit a rock that is approximately the size of a rhinoceros. Should ... A: This is the ideal application for the Boulder Buster, RocKracker, or NONEX. The Boulder Buster ... | |
| Excavating Rock | 1/9/2008 |
| Q: Is it remotely practical for me to think I could "excavate" rock ledge in by basement to accomodate ... A: The trick to breaking rock with a jackjammer is to have the rock on a hard surface and starting ... | |
| Excavating Rock | 1/4/2008 |
| Q: Is it remotely practical for me to think I could "excavate" rock ledge in by basement to accomodate ... A: First let me apologize for not answering you sooner. I have been preoccupied with personal issues ... | |
| sewer lines through bedrock | 1/4/2008 |
| Q: There is a property that I wish to build on that is at the end of a culdesac in an established ... A: Actually, you can blast that close. You just use small holes on close spacings, little charges, and ... | |
| blasting near pipe 2 | 12/22/2007 |
| Q: Test blasting near pipe 8 inches API5LX65 buried 5 feet depth, No blasting specification. Results: ... A: Please refer to my earlier reply stressing the consideration of peak particle displacements and ... | |
| blasting near pipeline | 12/21/2007 |
| Q: Our company test blasting near a slurry pipeline distance 30 feet, PPV result 30,98 mm/seg (1,22 ... A: Do you mean that the pipeline depth is 5 ft? or that you measured the 1.22 in/seg (inches para ... | |
| Subsurface conditions rock removal | 12/13/2007 |
| Q: We are building a new home in central PA. Construction started around two weeks ago and they were ... A: They probably used a hydraulic hammer (hoe-ram) to excavate the rock. These are powered maul points ... | |
| foundations on sandy (beach) soil | 12/5/2007 |
| Q: We are getting through our permits for our coastal zone and are hoping to raise our house this ... A: You need a decent soil report before investing in a foundation system in this case. I know you are ... | |
| Rock on a Home Building Site | 11/19/2007 |
| Q: We are looking at a building site that is up on a cliff overlooking a lake. There is quite a bit of ... A: How level is the site? If it's not level then you are involved in cut and fill operations. You ... | |
| well water problem from blasting? | 10/24/2007 |
| Q: Cummings my name is Jesse Quimby a resident of Barrington NH. I was hoping that you could take just ... A: First I have to confess that I am not an expert in the issue of water well response to blasting, so ... | |
| Blasting within 250' of my home; Q's to ask blast. company/concerns | 9/17/2007 |
| Q: I own an antique home w/granite slab & rock foundation, old windows, 600' dug well (H2O), septic ... A: Sorry I was traveling and in the field so did not get you inquiry until this morning. First, ... | |
| Rocks in the plot we are planning to purchase | 9/14/2007 |
| Q: We would like to purchase a plot(1200 square feet) in Electronic city, Bangalore,India. But the ... A: It all depends if the rocks are small or large, and if they are loose boulders in soil or if they ... | |
| Root cellar restoration | 9/13/2007 |
| Q: I'm seeking repair and restoration information for a circa 1840's root cellar. It is built into a ... A: Masonry arches derive their stability from the ring stresses developed around the perimeter. If the ... | |
| Root cellar restoration | 9/11/2007 |
| Q: I'm seeking repair and restoration information for a circa 1840's root cellar. It is built into a ... A: Is it tunnelled into the hillside or just built out from a hillside cut with the brick arch ... | |
| foundation on a steep slope | 8/23/2007 |
| Q: I have a lakeside lot with a fairly steep slope. I'd like to put a house on it. How can I ... A: There are many ways to measure a slope in the field. The simplest way is to use a hand level, a ... | |
| Moving rocks on island home | 8/22/2007 |
| Q: I am trying to move rocks of 200/350 lbs down to shoreline at an island home. Island is an old ... A: Estimate/measure the length, width, and height in ft/fractions of ft; multiply to get the volume (in ... | |
| Moving rocks on island home | 8/22/2007 |
| Q: I am trying to move rocks of 200/350 lbs down to shoreline at an island home. Island is an old ... A: You can fool around with hand tools and "pissant" them along but if you have any distance to go at ... | |
| digging a basement after the fact | 8/6/2007 |
| Q: We live in a 15+doublewide home, that we have remodeled from the inside ... A: First, I'm confused about the foundation arrangement for this structure. Is it slab on grade or ... | |
| pinning footing to exist rock | 8/5/2007 |
| Q: Mr Cummings - I'm working on a three story wood frame townhome and the footings are going to be ... A: In general, anchors are designed to resist uplift. The shear strength of the steel elements forming ... | |
| Residential footing | 7/24/2007 |
| Q: I am under contract on a house and discovered that the sun room and second story addition were added ... A: This kind of retrofit is a poor substitute for underpinning but you might be able to get away with ... | |
| Oceanfront house on a steep hill | 7/11/2007 |
| Q: I'm trying to build a 2-story house (3000 sq.ft., 60'W x 36'D) on a hill next to a beach in Seattle. ... A: Cast in place concrete piers are a method, not a marketed product, so I don't know of any websites. ... | |
| Oceanfront house on a steep hill | 7/11/2007 |
| Q: I'm trying to build a 2-story house (3000 sq.ft., 60'W x 36'D) on a hill next to a beach in Seattle. ... A: Why the piles at all? Is the foundation material some kind of loose shifting sand? Or are the piles ... | |
| foundation pinning to solid rock | 6/28/2007 |
| Q: I live in Norther Minnesota and am going to build on a exposed solid rock outcropping. I have read ... A: If you are pouring directly on the rock you need to remove any loose or extensively weathered rock ... | |
| Site Preparation | 6/14/2007 |
| Q: Our company is looking to develop a fairly large site in northeastern CT that we believe has ... A: Odd.....I received no notice of non-delivery, and the email address I typed in looked correct. Just ... | |
| Site Preparation | 6/12/2007 |
| Q: Our company is looking to develop a fairly large site in northeastern CT that we believe has ... A: Sounds like the kind of project our company ordinarily does as a compensated service! The first ... | |
| ROCK | 6/11/2007 |
| Q: I'm in the process of installing a chain link fence. I hit a BIG ROCK right where I need to install ... A: Here's the thing about expansive grouts -- they will crack off the rock but not displace it much, ... | |
| What to do with large rocks | 6/8/2007 |
| Q: We just finishing digging our basement and ended up with some beautiful, large glacial rocks we are ... A: The trouble with accumulations of large rocks is that they tend to look bony and like a mistake ... | |
| construction | 6/2/2007 |
| Q: A: I am answering you with the understanding that this is not a homework question. If you were to cut ... | |
| Drilling into Rock | 5/20/2007 |
| Q: Request: Please suggest a practical and effective approach, and the appropraite tools (e.g., drill, ... A: Neither. If your rock is like most New England coastal igneous or meta-igneous rock, high carbon ... | |
| Drilling into Rock | 5/19/2007 |
| Q: Request: Please suggest a practical and effective approach, and the appropraite tools (e.g., drill, ... A: You should anchor the footings at an elevation that will be below the frost line, I think. I don't ... | |
| steep hill foundation | 5/14/2007 |
| Q: My wife and i have found 5 acres on the water that we would like to build a little weekend cottage ... A: Really, you can do it either way. I cannot tell you which is cheaper because the answer is too site ... | |
| reading a grade rod | 5/9/2007 |
| Q: sir ! i need to learn how to read a grade rod and to understand what the readings are on cut and ... A: Grade rods are graduated in feet, tenths, and hundredths of feet. The rod is used to determine ... | |
| pinning foundation to ledge | 5/2/2007 |
| Q: Building a roughly 20'x 20'addition onto @10 degree sloped ledge which has been chipped down to a ... A: How much are you spending on the addition? Now, how much is due to the rebar pins? Probably a ... | |
| Excavating retaining wall | 5/1/2007 |
| Q: I own the hillside, my HOA covenant says I can not make any deep grading cuts to the hillside approx ... A: First let me say I don't live in a neighborhood with a HOA and every time I hear stories like yours ... | |
| 4ft Crawl space to New Room | 11/28/2006 |
| Q: we bought our home in Malden, MA (just north of Boston) about 25 years ago. 20 years ago, we added a ... A: If I understand you correctly, the original 1-story addition is now a 2-story addition. It is, I ... | |
| Lake Construction | 11/1/2006 |
| Q: I'm actually a fellow volunteer in the real estate department. Hopefully you can shed some light on ... A: I can't speak to all the legal issues. If you have a private lake you have to fill it somehow and ... | |
| Best way to prep a site for foundation digging | 9/26/2006 |
| Q: I have 30 days to get a site ready for a Modular Home, I have a floor guy to do the concrete, I have ... A: I'm having trouble picturing the issue. I think I would start digging the long wall first so you ... | |
| Preparing correct footing base after blasting | 9/25/2006 |
| Q: We have just finished excavating our foundation which was just blasted this week. The blasting ... A: Depends on the footing loads. Most residential structures are not that heavy so if you gouge out ... | |
| Asphalt Millings | 8/26/2006 |
| Q: I recently acquired some asphalt millings to pave a rear lot for dust control. I elected to use ... A: I wish I could be more help to you but asphalt millings are not my bag. I can offer this, though. ... | |
| generators | 8/19/2006 |
| Q: I work on a construction site. I have argued with my boss that all towed generators have to be ... A: This is not really my bag and you should get confirmation from somebody else. The reason I am ... | |
| concrete and rain | 8/3/2006 |
| Q: We are building a new home and had the footings poured today in a heavy rain. Will it be ok? A: Concrete cures under water about as well as it does in the dry, in fact better from the standpoint ... | |
| Rock Removal | 7/9/2006 |
| Q: I have a job in Northern NJ where we are builing a 40x80 home witha 9' deep basement we encountered ... A: $100/cy for a small job seems like a lot, maybe the blaster thought there were extenuating ... | |
| Rock blasting for raod widening near crude oil pipeline. | 6/9/2006 |
| Q: Sir I have calculated the peak stress induced in a 34 inch diameter crude oil pipeline located 130 ... A: I hate it when pipeline blast vibration issues come up because so often the damage potential is ... | |
| Foundation & Basement after Blasting | 6/4/2006 |
| Q: We are buying a home that is currently just begun construction. The area where the foundation will ... A: For the most part, if a foundation for a single detached residential structure requires blasting, ... | |
| boulders | 3/26/2006 |
| Q: We just moved into a new house and we have a few large rocks in the back yard. They are embedded in ... A: A Bobcat will lift a lot, actually. There are different sizes of Bobcat. Check with the rental ... | |
| Water problems | 3/23/2006 |
| Q: We live on a farm in central New York State. There is a 25' x 50' pole barn on the property. This ... A: It sounds like the french drain is the most cost effective thing to try right now. If the soil ... | |
| Water problems | 3/19/2006 |
| Q: We live on a farm in central New York State. There is a 25' x 50' pole barn on the property. This ... A: I did a little sketch in order to better understand the layout. It sounds like the heave is ... | |
| How to keep hillside in place? | 2/16/2006 |
| Q: Mr. Cummings; Thanks for your detailed response. Your understanding of my project and site is ... A: I'm not a structural engineer but the 6x8 inch blocks should be fine for a small wall like this. ... | |
| How to keep hillside in place? | 2/13/2006 |
| Q: Cummings; I own several acres of land in Divide, Colorado (near Pikes Peak). I have an approx. ... A: You have a classic problem in soil mechanics. And you are quite right to be concerned about the ... | |
| Trenching | 1/27/2006 |
| Q: I have some property about 20 miles S on 287 from Laramie and about 3 miles E. It is decomposed ... A: Sorry to be delayed but AllExpert's servers kept crashing when I sent my replies. Went on for ... | |
| Earthmoving machinery | 1/27/2006 |
| Q: What are the names of some of the larger manufacturers of earthmoving equipment, like graders, ... A: Sorry for the delay. For several days AllExpert's servers kept crashing whenever I tried to reply ... | |
| peak particle velocity | 12/19/2005 |
| Q: We are currently blasting at a construction site in the Hudson Valley area of New York. Our ... A: I'm not sure what exactly the spec writer means by "maximum resultant peak particle velocity" ... | |
| blasting in Texas | 6/13/2005 |
| Q: Where does one receive a permit to blast rock or ground? Is such a permit easy to receive? I'd like ... A: Check with the Texas registrar of commercial contractors. They will be able to tell you about Texas ... | |
| Mine question | 6/13/2005 |
| Q: What do they call vehicles used to drive into mine passages in order to dig or drill ore from the ... A: Depends. Multi-boom drills are called drill jumbos. Powder is usually loaded by hand but ... | |
| water | 5/16/2005 |
| Q: I had asked the question about gallons and length of time to fill a lake. Thanks for your quick ... A: The question is not an engineering question, it is a question in basic solids geometry, which ... | |
| clink | 5/6/2005 |
| Q: In the cement industry, can you tell me what "Clinker" is? What is used for? A: "clinker" in coal processing refers to the residual inert material remaining after coking. In ... | |
| roads | 4/1/2005 |
| Q: what causes pot holes on dirt roads? A: Good question. I am not aware of studies on this but there may be some. To the extent that pot ... | |
| Foundation advantages | 3/28/2005 |
| Q: I am doing a project on the advantages and disadvantages of different types of foundations and was ... A: The main difference I can think of is cost. Masonry if constructed properly will cost more, because ... | |
| Landscape | 1/8/2005 |
| Q: I have told that contractor I cannot be his sales, he understands. The construction industry is ... A: I make my living doing engineering designs that are built by construction contractors. Worse yet, ... | |
| it is about this contractor,... | 1/2/2005 |
| Q: it is about this contractor, he is a nice guy, but we don't have deep conversation, I feel empty ... A: I am not entirely clear who you are or what relationship you have to this contractor but my guess is ... | |
| Pile Driving | 11/18/2004 |
| Q: In regard to bridge construction, when did the use of driven piles become acceptable design? A ten ... A: I have no idea off the top of my head, because it depends on what you call "acceptable design". ... | |
| Basement Excavation, Weather, and footings | 11/9/2004 |
| Q: I'm helping my Mother-in Law with decisions related to building her home. Right now we're trying to ... A: First of all I am not in a position to judge the dispute between your two subcontractors, except ... | |
| blasing and excavation of a foundation | 9/14/2004 |
| Q: Now that the rock has been blasted, we have a follow up question, which is what kind of residues ... A: In all probability the explosive mainly used by your contractor would be ANFO, either dry or as a ... | |
| blasting | 8/31/2004 |
| Q: Who could you recomend to do some blasting on a project that has already been drilled? They must ... A: Try Franklin Drilling and Blasting out of Durango, CO. I know Jeff and he is as good as they come. ... | |
| blasing and excavation of a foundation | 7/28/2004 |
| Q: My husband and I are in the process of building a new home. The lot has ledge under 2 feet of ... A: I believe I answered this already. I don't know if it is a duplicate or if my original answer was ... | |
| Rock Removal | 7/22/2004 |
| Q: The existing foundation is actually 100 yrs old and does have a structure on top which we are ... A: I was unaware of your reply until now, and it has been so long I don't remember all the details of ... | |
| Rock Removal | 7/21/2004 |
| Q: I am building a house in the NE. My contractor found rock during excavation and tried using ... A: harmful? It depends on the qualifications of the blasting subcontractor and the type and extent of ... | |
| boring and jacking of utilitiies under streets | 7/12/2004 |
| Q: We have a manager here in city govt that wants to make it a standard policy to bore and jack all new ... A: I'm not qualified to evaluate boring and jacking feasibility of all kinds of projects but I am ... | |
Construction & Contractors
Answers by Expert:
Robert Cummings, P.E.
Top Expert on this page
Expertise
I can answer questions related to rock blasting, rock and soil excavation (such as tunnels and highway cuts), stability of such excavations, and foundations in rock and soil. I can also answer questions related to geology and mining.
Experience
30+ years as a geotechnical engineer and minerals engineer. Active consulting practice in rock blasting, geotechnical engineering, and rock mechanics for mining and heavy construction.
Organizations
Society of Mining Engineers, Deep Foundations Institute, Association of Engineering Geologists, and International Society of Explosives Engineers.
Publications
Mining Engineering, AEG Bulletin.
Education/Credentials
BS and MS Geological Engineering
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