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HomeMy WebLinkAboutBlue Heron Report - BLD Engineering / Geo-tech Reports - 5/20/2002 6-19-02; 12:58PM;Bradley Scott Inc. ;360 479 5499 # 2/ 4 Allen L. Hart Engineering Geologist 1720 North Oakes, Tacoma, Washington 98406 (253) 752-8963 May 20, 2002 Project No. 0205031 Robert Macht Bradley Scott Real Estate, Inc. 400 Warren Avenue, Suite 450 Bremerton, Washington 98337 Blue Heron Resort Condominium 6520 East State Route 106 Union,Washington This letter is prepared at your request and follows our meeting at the referenced site on May 14,2002 and serves to summarize my comments made at that time. The purpose of our meeting was to briefly review site moisture,ground, and storm water conditions and recommend possible courses of action to resolve the reported water and moisture problems.As I told you at the start of our meeting,the cause(s)of water and moisture problems are frequently elusive and if identified multi-sourced, and difficult and costly to rectify. Similarly, if the problem is studied in detail, including installation of monitoring wells with well observations being carried out over a period of months(seasons),it is costly and the end result is not uncommonly inconclusive and the effect of drainage recommendations problematic. Based on information provided by the resident manager and you, I strongly suspect that the identified moisture and water problems are multi-sourced and that there is some interbedding of fine-grained site soils with those of a coarser grained,more permeable nature. Should this be the actual case it may not be possible or practical to intercept water flows with any single system. As we discussed present ditch near the extra parking area and resident manager's residence is too shallow to have anything but a limited effect on storm water flows. Outlined below are two basic courses of action,which may be taken at this point in an effort to deal with the water and moisture problems.However, as I told you one of the first things that should be done is to have a topographic survey of the property completed at a two-foot contour interval. This mapping would give you a better picture site highs and lows and potential "natural"drainage paths. This drawing should also show the elevation of crawl space areas and underground utility routes. This drawing could also give you a better picture of seeps and water levels across the property and aid in developing a drainage plan. 6-19-02; 12:58PM;Bradley Scott Inc. ;360 479 5499 # 3/ 4 r Project No 0205031 Blue Heron Condominium May 20, 2002 Page No. 2 If you were to elect to have a study completed in an attempt to define seepage zones and recommend various means of correcting the problem(Note my comment in the first paragraph of this letter regarding studies.)a . number of borings would be drilled across the site with soil samples taken for laboratory testing and observation wells installed. I would anticipate that the wells would be monitored several times a month, particularly during the wet season,and crawl space areas periodically inspected. The data would be reviewed and analyzed and recommendations made. A rough estimate for such a study might be on the order of$30,000 t0 $38,000. Realizing that any report recommendations may or may not work you could try several measures without expending the time and cost of a study. As we discussed, most of the following measures are of the type that could possibly be presented as report recommendations. Do not expect that any single item below will solve the present water and moisture problems rather taken together they may work to mitigate the problem but only locally resolve the problem. • Defining building 1 and highway 106 as being on the west end of the property. Construct a French or curtain drain across the west,north and south sides of the property. To have a reasonable chance to be effective I would anticipate that across the west end of the property the drain would be on the order of six to eight feet in depth. If possible this depth should be maintained down the north and south sides of the property with the system discharging to daylight or into the storm drain system. Using the topographic map it may be found that the six to eight foot deep starting depth does not provide drainage across the entire compound. Should this be the case it may be desirable to add additional north-south lines across the property at appropriate depth locations. It should be noted that this drain system might not intercept water showing up as springs or seeps below some of the units. If this is the case you should anticipate the need to construct sump systems as outlined below. • Check all down spout piping to assure that it is not perforated pipe. Replace all perforated pipe with solid pipe and confirm that all down spouts discharge into the storm drain system. • Confirm that dry wells are not in use on the property. • Provide good, unobstructed, cross ventilation in all crawl space areas. Ventilation should be maintained the year around. Allen L.Hart Engineering Geologist 1720 North Oakes,Tacoma,Washington 98406 6-19-02; 12:58PM;Bradley Scott Inc. ;360 479 5499 # 4/ 4 ` o Project No 0205031 Blue Heron Condominium May 20,2002 Page No. 3 • Yard drains should be provided in areas where water accumulates in grassed or landscaped areas. Yard drain piping should be extended to discharge into the storm drain system. • Soil, landscaping,walkways and pavements should be sloped to drain away from the structure for a distance of at least five feet. • All pavement areas should be bermed or curbed such that storm runoff is intercepted, collected and tight-lined into the storm drainage system. • Inspect all water transport systems, i.e., water supply the project, septic system piping, and landscape watering systems,to assure that there are no leaks. • Grade all crawl space areas to drain to a sump. The entire space could be graded to drain or channels leading to the sump cut. If a fairly deep sump is constructed and lined with a perforated pipe,perforated drum,or similar system it may be possible to reduce the water level to some depth below the crawl space ground surface and aid in drying the crawl space area. Water from the sump should be tight-lined into the storm drain system. Depending on grades at some locations it may be possible to gravity drain from the sump under the building foundation or through the stem wall into the storm drain. NOTE: If a gravity drain is used, depending on the construction of the storm drainage system and outfall location it may be desirable to screen or otherwise block the pipe to prevent vermin from accessing the crawl space via the sump discharge pipe. Construction of French or curtain drains, extending to no less than a foot below footing level, on the up slope side of the structures could aid in intercepting some of the water entering the crawl space area. Piping in the drain itself should be perforated but away from the building and extending to the storm drain system pipe should be solid. I hope that the foregoing comments are of assistance; if I may be of additional service lease feel free to call y ' p my office. '�0 f Sincerely, °� Enpinaering Gaol (:t Allen L. Hart, CPG, RG/CPG $ae Engineering Geologist ��nse ALLEN L. HART Allen L Hart Engineering Geologist 1720 North Oakes,Tacoma,Washington 98406