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Leighton A. White Inc., Complete Site Work Services in Milford, NH

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Dorrs Pond Dam Rebuild

For 37 yrs LAW, Inc has shined in the more difficult jobs…the jobs no one else wants to deal with. One such project was the Dorrs Dam rebuild in Manchester, NH. It showcased new technology (equipment) meshing with one of man’s oldest techniques (siphoning water) in some very non-conducive conditions.

Originally printed in the Union Leader on Monday, February 20, 2012

Five times in the past seven years rainfall in Manchester has been intense enough to cause water levels in Dorrs Pond in Livingston Park to rise above dam level, bringing flow crashing down onto the rocks below.  Repeated overtopping can compromise the integrity of a dam by washing away soil necessary to its stability.  As a result, the city has recently completed a project intended to fortify the area downstream of the dam to withstand overtopping at a rate more than twice that expected during a 100 year storm.

Leighton A White Inc. of Milford was contracted by the Parks, Recreation, and Cemetery Division of the Highway Department to install some 2500 sf of curbing on a concrete base to resist the forces of moving water.  The $100,000 project was designed by TFM   Inc. of Bedford.  It was reviewed and approved by the NH State Dam Bureau and was   funded through grants from the NHDES and the EPA. Dam specialists HTE Northeast   Inc. provided inspection services.

Dorrs Pond Dam is classified as a high hazard dam by the state because people live immediately downstream and failure may result in loss of life.  As a result, state requirements include the ability to withstand 2.5 times a 100 year storm.  Rains corresponding with such a storm would result in water overtopping the dam by two feet; hence the use of robust granite curbstone pieces (minimum size of 3 feet x 1.5 feet x 6 inches).  Physically the dam is made up of two walls, a 1.5 foot wide concrete wall along the pond   side, and a stone masonry wall capped with concrete along the downstream side.  The   nine feet of space between them consists of compacted earth fill, and its length is   approximately 125 feet.  The dam passes pond flow via a 6.5 foot wide spillway, and it last saw work during a rehabilitation conducted in 1986.

Like the previous work, current tasks focused on minimizing erosion on the downstream side to prevent conditions that could lead to dam failure.  In just over a month of work at the dam, the contractor removed two feet of soil, built the ground back up with compacted gravel, and placed approximately 200 pieces of used granite curbing on top creating an unerodable surface.  The curbstones were laid on their side, and were grouted   together with concrete.  The spillway was doubly armored, first with two feet of 4000 psi   concrete, and then with granite slabs.  Granite was chosen not only for its hardness but because it was readily available, relatively inexpensive, and aesthetically pleasing.

In order to dig in the ground in the most favorable conditions Leighton White employed the use of four six-inch diameter siphons to lower the pond level to approximately three feet below the spillway.  Siphons, depicted in Egyptian reliefs as far back as 1500 BC,  use atmospheric pressure to pull water out of the pond, pass it over the dam, and   discharge it below the worksite.  The use of siphons was a perfect application on the   project because once in operation they required no external power and ran 24 hours a day.    Lowered pond levels made for easier and more stable excavation for the contractor.  With the project complete, the Dorrs Pond Dam is fully compliant with NHDES   regulations. Patrons of Livingston park, whether in the adjacent playground or out on the mile-long trail around the pond can admire the stonework for decades to come.


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Complete Site Work Services

Leighton A. White, Inc. provides commercial, industrial, municipal (civil/public works), institutional, and residential excavation and site work services, communications (cell tower) site construction and development, athletic field construction, as well as other specialty sitework services in New Hampshire and Northern Massachusetts.

Areas served include but are not limited to Milford, Wilton, Rindge, Peterborough, Keene, Concord, Merrimack, Bedford, Manchester, Hooksett, Brookline, Hollis, Nashua, Raymond, Exeter, Hampton, Portsmouth and beyond.

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Valued Customers Say

(Re: a tower site with two approval delays) A typical scenario at that point would have been to start winter construction, with the expectation of bringing the site on-line sometime towards the end of Jan. I met with your firm though, and was assured that through whatever contortions necessary, you would be able to work within my unrealistic expectations. It is a credit to everyone in your organization that official site turn-up happened Dec.…John Stevens, P.E.NYNEX Mobile Communications
Completing this project within the aggressive schedule set by Bell Atlantic NYNEX Mobile, Inc. would not have been possible without your efforts. Your attention to detail, spirit of cooperation and professionalism were essential to the success of this project. I would be happy to recommend Leighton A. White, Inc. to any potential clients.Kevin Ferington, P.E., ErdmanAnthony and Assoc., Inc.
This project could never have happened if I had not used your firm and your personal expertise in the team effort. If I can ever be of service to you in recommending your firm for work, specifically the tight time constraints or the difficult coordination project, I would be happy to do that.John Stevens, P.E.Bell Atlantic NYNEX Mobile
Thank you for your beautiful cutting work and for your consideration and patience.Sandra D.
Just a note to tell you how happy we are with the work your crew did on our yard and drive. CM is a fine representative of your company- so polite and diligent that I thought he must be part of your family! Great job again guys!Sue J.
If we ever have to have any lawn work done again, we’ll know whom to call and to recommend! It hasn’t been a week yet and already little patches of grass are beginning to show. I want you to know, too, that we appreciate the men who work for you. They were busy every minute and very politeLouise and Mario
I just wanted to tell you what a positive experience my recent clay delivery from your company was. Ron called me to arrange delivery and was very polite and helpful and I can’t say enough in praise of the truck driver who worked hard to assure my satisfaction in how and where he placed the clay. All of you have been courteous and thoughtful.Alice A.
We were more than satisfied with the job you did on the demolition of our barn. We were impressed with your crew…extremely pleased with how careful and conscientious they were, which is a very rare quality these days! We are looking forward to you coming back in the spring to put on the finishing touches with loam and grading.Neal and Sandy G.
I just wanted to compliment you and your people on the excellent work you did in accomplishing the oil tank removal project on our property. I was impressed with how well everything was coordinated among your employees and all the subcontractors and government officials who were involved in the project. It was a professional job, well done.James Tuzzeo, Ph.D.Permattach Diamond Tool Corp.
We have employed Leighton A. White many times over the years for projects large and small. They always are fully prepared fbr the job, sending the right equipment and personnel to get it done. They consistently meet the timelines and budgets we set because they plan their approach ‘using the experience they have acquired over their decades of business. We look forward to working with them again soon.Peter D. Capano, P.E., Chief, Parks, Recreation & Cemetery, CityManchester

Contact Info

Leighton A. White, Inc.
138 Elm Street
Milford, NH 03055

Tel: 603.673.2294
Fax: 603.672.8320

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