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HomeMy WebLinkAbout07/17/1990, 4 - EARLY GRADING PERMIT AUTHORIZATION - REQUEST TO STOCKPILE AND TREAT SOILS CONTAMINATED WITH PETROLE MEETING DATE: ������►�►►i(�IIIIIIIIIP►►► ��IIIU city of San Luis OBlspo 7-/?- o COUNCIL AGENDA REPORT ITEM NUMBER: 0 FROM: Arnold B. Jonas Community Development Director; BY: Pam Ricci., Associate Planner}' SUBJECT: Early Grading Permit Authorization —Request to stockpile and treat soils contaminated with petroleum fuel oil on property located within the Southern Pacific Railroad right-of-way, adjacent to the site of the proposed condominium project known as Fairview Station (2225 Bushnell Street) . CAO RECOMMENDATION: Adopt a resolution authorizing stockpiling based on findings and subject to conditions. BACKGROUND Situation The applicants want City Council authorization to stockpile and treat contaminated soils excavated from the site of the proposed Fairview Station condominiums in the adjacent railroad right-of- way. The Fairview Station site was used as a railroad refueling facility up until the 1950s. Because of this known past use of the site, there was a strong possibility that either the soil or groundwater had been contaminated with petroleum hydrocarbons from fuel oils stored there. For this reason, the .City requested that a environmental site assessment and a site remediation work plan be submitted and approved along with plans for the proposed condominium project. Contaminated soils were excavated from the Fairview Station site between May 29, 1990 and June 11, 1990. The quantity of contaminated soils found on the site (5600 cubic yards) was much greater than the originally projected quantity included in earlier reports (1900 cubic yards) . The original site remediation work plan, presented to the Planning Commission and City Council with consideration of the tract map for the Fairview Station project in October and November of 1989, indicated that all contaminated soils would be removed from the site and transported to an appropriate disposal site. Contaminated soils were defined as those soils with petroleum hydrocarbon concentrations in excess of 100 mg/kg (above defined City action levels) . During plan check of the project, this remediation plan was revised several times. The last plan reviewed by staff estimated that there was approximately 1,900 cubic yards of contaminated soil existing on the site. That plan indicated that 400 cubic yards of soil would be treated on site and the remaining 1,500 cubic yards would be transported to a location within the County for treatment. �,���,►�u��iIIfIIIIIIn ��I�N city of San Luis OBIspo COUNCIL AGENDA REPORT Stockpiling Permit Page 2 Contaminated soils have been removed from the site of the proposed condominiums and are being stored on property directly to the north of the site, also owned by the applicants, and within the adjacent railroad right-of.-way. Rather than hauling the contaminated soils to an approved disposal site, the applicants would like to stockpile the soils in the railroad right-of-way and treat them there through the clean-up process known as bioremediation. Significant Impacts If the request is not approved, the contaminated soils will need to be hauled away to an approved disposal site. Residents in the adjoining neighborhood will notice increased noise and traffic from trucks hauling away the soil. Because of the large quantity of contaminated soils, it would require approximately 300 truckloads to haul away the soils. With approval of the request, staff is suggesting conditions to limit impacts to the neighborhood including dust control, site restoration and fencing around stockpiles. Data Summary Address: 2225 Bushnell Street Applicants: The Petra Group, Inc. Representatives: Bruce. Houseman and Keith Gurnee Zoning: R-2-S General Plan: Medium Density Residential Environmental Status: Categorically exempt under Class 4, Minor Alterations to Land, Section 15304. of CEQA Guidelines DISCUSSION 1. Volume of Contaminated Soils The primary reason that this matter is before the council is that the volume of contaminated soils actually excavated from the site. (5600 cubic yards) was so much greater than originally estimated quantities (1900 cubic yards) . Projecting the extent of soil contamination prior to actual excavation is difficult because the variations within the soil stratigraphy that determine how contaminants will spread cannot be seen from the surface. Until the excavation process is actually underway, there is no foolproof method to projecting the quantity and the extent of contaminated soils. -2 ��� ��Hi�HIIIIIIiPnN�gIUIN City of San LUIS OBISPO COUNCIL AGENDA REPORT Stockpiling Permit Page 3 With this particular site, significantly more contaminated soil was found under an excavated retaining wall than expected, and contaminated soils were inadvertently mixed together with clean uncompacted fill deposited above them during excavation. Because of this dramatic difference between actual and projected quantities of contaminated soils, the applicants were forced to consider alternatives to hauling away all of the contaminated soils. The impacts associated with hauling the existing volume of contaminated soil include the greatly escalated cost to the applicants, the noise and added traffic to the neighborhood, and the environmental implications associated with dumping the soils at another site without removing the contaminants. 2. Proposed Bioremediation Treatment Process The applicants want to treat all 5600 cubic yards of contaminated soils excavated from the site in the adjacent railroad right-of- way through the process of bioremediation. Bioremediation is a process where soils are isolated and injected with special bacteria that break down and digest contaminants in the soil, degrading the oil into nonhazardous natural byproducts. The soils are monitored until target concentrations are maintained. once these target concentrations are achieved, • the soils can be reused, usually under roadways and in driveway and parking lot areas. A more detailed description of the bioremediation process is discussed in the attached Earth Systems work plan report. Bioremediation is considered the environmentally preferred alternative because the process eliminates the contaminants existing in the soil rather than simply transporting the contaminated soils from one location to another. Figure 1 of the attached Earth Systems report shows the proposed treatment area for contaminated soils in the railroad right-of- way. Contaminated soils will be laid out on black polyethylene sheeting to prevent contact with underlying soils. The soils will be piled to a height of about 18 inches and covered with the same polyethylene sheeting. Stockpiles will be enclosed with cyclone fencing. A condition of recommended approval calls for wood slats to be installed in fencing to further screen stockpiles. Openings between stockpiles allow for continued pedestrian access through the area. •3 city O� San tins OBISPO Worms COUNCIL AGENDA REPORT Stockpiling Permit Page 4 All contaminated soils are proposed to be treated in the railroad right-of-way. In staff's opinion, the railroad right-of-way is the best location for treatment since it is farther away from residences, less visible because of its lower elevation and will not interfere with other on-going uses in the vicinity. Soils currently stockpiled on other property owned by the applicants at 2120 Florence Avenue, directly north of the Fairview Station site, will also be moved to the railroad right-of-way because the right- of-way is a preferred treatment location for the reasons previously noted. The revised remedial work plan submitted estimates that treatment will take about six months. Staff is recommending as a condition of approval that the stockpiling of contaminated soils be authorized for a year, with the possibility of one 6-month extension being authorized administratively. The applicants have indicated that they would like to use the stockpiled soil once treated as fill material on property they own immediately to the north and the south of the Fairview Station site. While hazardous compounds are essentially removed through the bioremediation treatment process, some traces of contaminants may remain in heavier clay soils. Therefore, staff may have concerns with treated soils being reused as fill material in projects designed for residential occupancy. As previously mentioned, treated soils are most commonly used in driveway and parking lot areas. Since it is unlikely that 5600 cubic yards of soil will be used for such improvements in the immediate vicinity of the site where soils are now stored, it will probably be necessary to transport treated soils to one or more locations for reuse. In any case, staff would need more information from the applicants' soils engineer on contaminant levels in the soil after treatment before making any specific recommendations regarding their use. The applicants are also aware that using the treated soils on either of the sites they own in the vicinity prior to approval of project development plans would again require council approval of an early grading permit. 3. Dust Management Plan The Community Development and Fire Departments have received several complaints from neighbors regarding dust generated with earth-moving activities on the Fairview Station site. Staff required that the applicant submit a dust management plan outlining measures to be taken during all phases of project construction to limit dust generation. /fit_ city of san tuis oBispo a COUNCIL AGENDA REPORT Stockpiling Permit Page 5 The applicants' dust management plan is attached. A slightly revised version of that plan has been incorporated into conditions in the attached resolution supporting approval of the stockpiling permit. If followed, measures included in the plan should keep dust levels associated with construction activities to a minimum. CONCURRENCES The Fire Department has reviewed this report and concurred with the staff recommendation. ALTERNATIVES 1. The Council may adopt Resolution No. 2 which would deny the request and require that all contaminated soils be removed and transported to an approved disposal site. Staff is concerned with the amount of noise and truck traffic associated with this alternative. If this alternative is adopted, a condition is recommended that a plan for removing -- soils be submitted to and approved by the Community Development and Fire Departments so that the amount of truck traffic through the neighborhood can be monitored. 2. The Council may continue review with direction to the appellants and staff. This alternative would be appropriate if the council feels there is additional information needed, or if they would like to see changes made in plans, prior to rendering a decision. RECOMMENDATION Staff recommends that the City Council authorize issuance of the requested stockpiling permit, based on the findings and subject to the conditions contained in the attached resolution. Attachments: Draft Resolutions Figure 1 - Proposed treatment area and vicinity Earth Systems Revised Remedial Action Plan Dust Management .Plan d:soils.wp RESOLUTION NO. (1990 Series) A RESOLUTION OF THE COUNCIL OF THE CITY OF SAN LUIS OBISPO AUTHORIZING ISSUANCE OF A GRADING PERMIT TO ALLOW STOCKPILING ON A SITE LOCATED WITHIN THE SOUTHERN PACIFIC RAILROAD RIGHT-OF-WAY ADJACENT TO THE SITE OF THE FAIRVIEW STATION CONDOMINIUMS AT 2225 BUSHNELL STREET WHEREAS, the City Council received a request for a stockpiling grading permit for property located within the Southern Pacific Railroad right-of-way adjacent to the site of the Fairview Station Condominiums at 2225 Bushnell Street; and WHEREAS, the council has considered the reports of staff, public testimony, and materials submitted by the applicant; and WHEREAS, the potential environmental impacts of the project have been evaluated in accordance with the California Environmental Quality Act and the city' s Environmental Impact Procedures and Guidelines. NOW, THEREFORE, the council resolves to authorize issuance of a grading permit as follows: SECTION 1. Findings. This council finds: 1. The proposed grading operation will not adversely affect the health, safety and welfare of . persons residing or working on the site or in the vicinity, '. 2 . The proposed grading operation is consistent with the city's grading ordinance. 3 . The proposed grading operation is exempt from environmental review. SECTION 2. Conditions: 1. The early grading authorizing stockpiling located on a site O within the Southern Pacific Railroad right-of-way adjacent to the site of the Fairview Station Condominiums at 2225 Bushnell Street shall be valid for a period of one year from n - Resolution No. (1990 Series) Grading Permit J Page 2 the date of permit issuance from the Building Division. One time extension of the permit, not to exceed a period of six months, may be requested in writing prior to expiration of the permit to the approval of the Community Development Director. The applicant's written request needs to document any extenuating circumstances that would warrant an extension. 2 . The applicants shall submit an application and appropriate plans for a grading period as outlined in Section 15.44. 16 of the Municipal Code (Grading Ordinance) . Stockpiling of contaminated soils shall be completed as outlined in the Earth Systems remedial work plan dated June 29 , 1990. 3 . The applicants shall deposit a cash surety guaranteeing proper maintenance of stockpiles and restoration of the property to its present condition as required by the Community Development Department. 4 . Consistent with Section 15.44 .270, all graded surfaces shall be wetted, protected or contained in such a manner as to prevent dust or spill upon any adjoining property gr street. The following measures shall constitute the Fairview Station dust_management plan and shall remain in effect during all phases of that project's construction and during the time that contaminated soils are stockpiled and treated within the Southern Pacific Railroad right-of—way: a. Regular wetting of roads and graded areas (at least twice daily with complete coverage of all active areas) ; b. Increasing frequency of watering whenever winds exceed 15 mph; C. Cessation ofgrading actvities during periods of high winds over 25 mph; d. Direct application of water on material being excavated and/or transported onsite or offsite;. e. Watering material stockpiles; and f. Periodic washdowns, or mechanical streetsweeping, of Florence Avenue .and Bushnell and. Bishop Streets in the vicinity of the construction site. Resolution No. (1990 , Series) Grading Permit Page 3 . 5. The applicants shall install wood slates in cyclone fencing around stockpiles to the satisfaction of the Community Development Department. On motion of seconded by and on the following roll call vote: AYES: NOES: ABSENT: the foregoing resolution was passed and adopted this day of , 1990. Mayor ATTEST: City Clerk APPROVED: it A inistrative Officer - t n l Community Devel p ent Director RESOLUTION NO. (1990 Series) A RESOLUTION OF THE COUNCIL OF THE CITY OF SAN LUIS OBISPO DENYING ISSUANCE OF A GRADING PERMIT TO ALLOW STOCKPILING ON A SITE LOCATED WITHIN THE SOUTHERN PACIFIC RAILROAD RIGHT-OF-WAY ADJACENT TO THE SITE OF THE FAIRVIEW STATION CONDOMINIUMS AT 2225 BUSHNELL STREET WHEREAS, the City Council received. a request for a stockpiling grading permit for property located within the Southern Pacific Railroad right-of-way adjacent to the site of the Fairview Station Condominiums at 2225 Bushnell Street; and WHEREAS, the council has considered the reports of staff, public testimony, and materials submitted by the applicant; and WHEREAS, the potential environmental impacts of the project have been evaluated in accordance with the California Environmental Quality Act and the city's Environmental Impact Procedures and Guidelines. O NOW, THEREFORE, the council resolves to deny issuance of a grading permit as follows: SECTION 1. Findings. This council finds: 1. The proposed grading operation will adversely affect the health, safety and welfare of persons residing or working on -the site or in the vicinity. 2 . The proposed grading operation is inconsistent with the city's grading ordinance.. SECTION 2 . Within thirty days of this resolution, the applicants shall submit a plan for removing contaminated soils to the Community Development and Fire Departments for review and approval. The plan shall specifically state the number of truck trips per day needed to haul soils away and include a timeframe for completion. On motion of �- 9 i O Resolution No. (1990 Series) Grading Permit Page 2 seconded by and on the following roll call vote: AYES: NOES: ABSENT: the foregoing resolution was passed and adopted this day of 1990. Mayor ATTEST: City Clerk APPROVED: City F,dm'nistrative Officer i It rn ox - Community Dev pment Director . eX a m m 0 y 3 O mm z a ,eel w / � n o � n h 3I Reiv m o Fi N I Z m 0 3 T " n s 9 _ sm e rD 6 et w i y!dd a 3 m _ SigO� w -mm 71 c Qo cn a i 3 N_ D i m w $� 9 < I n _ m - e e D a e y � � m tl1Nm9 • _ D�D9 u Fn 10 N omoO ssti o 0 n a m Osi3 $ 0 m o s c p z 3 s s �.ti mmm, - N o p H m O o D c n' - z • 00 g Earth Systems Environmental , Inc. C' A 6emCer of The Eartn Systems Group 170-A Granada Drive - San Luis Obispo. CA 93401 • (805) 541-5983 FAX (805) 544-0531 June 29, 1990 Job No. ES-0109-PG3 Doc No. 9006-E083.WKP San Luis Obispo City Fire Department 748 Pismo Street San Luis Obispo, California 93401 Attention: Mr. .Mike Smith, Hazardous Materials Inspector Subject: Revised Remedial Action Plan Fairview Station Project--PETRA Enterprises Southwest Comer of Florence Avenue and Bushnell Street San Luis Obispo, California Gentlemen: At the request of PETRA Enterprises personnel, this letter presents a summary of activities conducted to date at the above referenced site; and provides a proposed work plan describing remedial action planned for contaminated soils removed from the site. In addition, the letter provides additional information regarding the proposed remediation plan which was requested by Mr. Michael Smith of the San Luis Obispo Fire Department and Ms. Pam Ricci of the City Planning Department. This work plan supersedes our earlier work plans dated June 20 and April 20, 1990 and the follow-up letters dated May 11 and May 18, 1990. Project Summary Excavation of Contaminated Soils Removal of contaminated, soils was begun on May 29. 1990 by the R. Burke Corporation of San Luis Obispo and completed on June 11, 1990. Excavation was accomplished using conventional earth-moving equipment, under the observation and testing of Earth Systems Environmental field personnel. As excavation progressed, analytical testing was conducted on-site, using a State-certified mobile laboratory, to verify that contaminants in remaining soils were below San Luis Obispo City Fire Department (SLOFD) action levels. After obtaining analytical results from the boundaries and bottom of the excavation showing that soils with TPH concentrations greater than 100 mg/kg had been removed in accordance with SLOFD requirements, the resultant excavation was partially backfilled and compacted in accordance with City of San Luis Obispo requirements .for fill placement. Pursuant to SLO Fire Department 2 June 29, 1990 the June 12, 1990 meeting attended by Bruce Houseman of PETRA Enterprises, Irwin Willis and Mike Smith of the City Fire Department, Tom Baasch and Bob Bishop of the City Engineering Department, and Pam Ricci of the City Planning Department, it was agreed that removal of contaminated soil from the Fairview Station project site has been completed to the City's requirements. Test results from samples taken during excavation indicate that soils remaining on the site do not contain hydrocarbon concentrations greater than 100 milligrams per kilogram (mg/kg), as required by the City Fire Department. Compaction testing of the fill was provided by the project Soil Engineer, Pacific Geoscience, Inc. A report showing the limits of excavated areas, sampling locations and analytical results is currently being prepared, and will be forwarded to the Fire Department upon completion. The volume of contaminated soil .removed from the site is approximately 5,600 cubic yards, which is more than was originally anticipated. The reasons for the larger-than-expected volume of soil are: • The area below the concrete retaining wall along the west property line, where earlier subsurface exploration was hindered by the presence of debris and trees, contained significantly more oil contamination than was expected. • The presence of approximately 15 feet of uncontaminated fill overlying contaminated soils, which resulted in significant amounts of clean soils being inadvertently mixed in with the contaminated soils during removal. The mixing of these soils was unavoidable given the site conditions, and probably added 10% to 15% to the total volume of soils stockpiled on-site. Bioremediation Procedures As outlined in the April 20, 1990 work plan and follow-up letters dated May 12 and May 18, 1990, it was proposed to treat the contaminated soils, using biological (bacterial application) methods, on two adjacent parcels owned by PETRA Enterprises. Verbal approval for this work plan was received from both the City Fire and Community Development Departments at a site meeting on April 23. Subsequently, it 9006-E083.WKP ES-0109-PG3 d-�� SLO Fire Department 3 June 29, 1990 G � was determined by the City and conveyed to PETRA Enterprises at the June 12 meeting that stockpile approval would need to be obtained from the San Luis Obispo City Council prior to allowing any further work on the project to proceed. Work on backfilling the excavation was halted by the City at that time, and no grading or remedial work has been performed since then. It is our understanding; that PETRA Enterprises has obtained an agreemcnt with the Southern Pacific Railroad Company (SPRR) for the use of the SPRR easement, to the west of the Fairview Station site, as a treatment area for the contaminated soils. The proposed area that will be used to spread the soils -for treatment is shown on Figure 1, attached with this report. The soil stockpile that presently occupies the vacant lot at the northeast comer of Florence Avenue and Rachel Street is proposed to be relocated to the right-of-way, in order to consolidate the treatment area. Use of the SPRR right-of-way possesses several advantages over the use of the PETRA properties as a treatment area, such as: C • The area available on the SPRR right-of-way is larger than the available PETRA properties, and will better accommodate the volume of soil that has been excavated. • The SPRR area is further from adjacent residential areas, and should present less of a visual impact to the surrounding area. • The cost for off-site disposal of the volume of soil excavated from the site would be in excess of $800,000.00. Besides being environmentally undesirable to simply transfer the contamination to another location, it would be impractical to implement such a remedial action, because of the insurmountable financial burden it would present to the property owner. Bioremediation of soils is preferable to off-site disposal, because the process destroys the contaminant in the soil, rather than simply moving the contaminant from one location to another. Another advantage of this technology is that future 9006-E083.WKP ES-0109-PG3 SLO Fire Department 4 June 29, 1990 _k Are liability for the generator is reduced, because the offending compounds are essentially removed once treatment is complete. The bioremediation process will involve the addition of microbes and nutrient- enriched water to contaminated soils. Currently, contaminated soil from the site has been placed on 10-mil polyethylene sheeting to prevent the contact of contaminated soils with underlying soils. A low earthen berm has been constructed around the perimeter of the piles, to prevent runoff from the piles onto the surrounding area , and vice-versa, in the event of rain. A chain link fence has been placed around the stockpile to restrict unauthorized access. to the treatment area. Pursuant to a re(fuest from the City, this fence will be provided with privacy slats to reduce the effects of wind on the plastic sheeting covering the piles, and to minimize visual impact to the surrounding area. If necessary, an open path between the piles can be provided to maintain pedestrian access across the railroad right-of-way. A description of the actual treatment process is provided below. - Specific quantities of nutrients will be added to the soils, along with a cultured strain of microbes and water. Debris (e.g. concrete, steel piping) not considered suitable for cultivation in the bioremediation pile will be segregated, and disposed of appropriately. Approximately 65 pounds of 15-15-15 fertilizer per 100 cubic yards of soil will be added to furnish an appropriate mixture of nutrients for bacterial growth. The fertilizer will be added as a liquid mixture to the piles. In addition, water will be added at a rate of approximately 3 to 5 gallons per cubic yard of soil. The water used in the treatment process will be reclaimed water obtained from the City wastewater treatment plant on Prado Road. After the fertilizer and water have been added, an appropriate quantity of Solmar Corporation Formulation L-104 cultured bacteria will be added to the prepared soil, cultivated and covered. The microbe culture proposed for use on this project is formulated to metabolize heavy, tarry types of oils, as well as aromatic hydrocarbons. It is composed of naturally occurring bacteria, which have been selectivcly concentrated on the basis of their ability to metabolize the types of contaminants known to exist in soils at the site. The by-products of biologic degradation of the hydrocarbons should consist primarily of carbon dioxide (CO2) and water. The treatment piles will be covered with polyethylene sheeting to prevent soil aeration, as well as to maintain soil moisture 9006-E083.WKP ES=0109-PG3 SLO Fire Department 5 June 29, 1990 C MR conditions. If necessary, moisture conditioning and maintenance of microbe populations in the treatment stockpiles will be performed periodically through application of additional soil nutrients and water. The time frame for completion of the project cannot be stated with certainty, due to various factors which affect the rate of the bioremediation process, such as ambient temperature. contaminant concentrations, nutrient levels; and soil type variations. We expect that the time necessary to reduce contaminant concentrations to levels that will be acceptable to regulatory agencies to be on the order of six. months from the beginningof treatment; however, this period could be shorter- or longer depending on the above variables. A more accurate time frame may be possible once the treatment is underway, and the rate of contaminant degradation can be evaluated. Soil Sam Mit g Procedures Soil sampling from both the excavation and stockpiles will be accomplished by grab sampling, or with a two-inch diameter hand sampler equipped with stainless steel liners for soil retention. Soil samples will be placed in stainless steel sleeves, sealed with Teflon. film, capped, and placed in plastic bags, and chilled for transport to a California certified laboratory, observing chain-of-custody procedures. All sampling equipment will be cleansed with tri-sodium phosphate (TSP) and rinsed with de-ionized water prior to sampling, and between sample intervals, to minimize the possibility of cross-contamination. Laboratory Analysis of Soil Sam lames After construction of the treatment piles, soil samples will be analyzed at a State-certified analytical laboratory. Samples will be analyzed for TPH by U.S. Environmental Protection Agency (EPA) methods 8015 and 418.1. Sampling Schedule After construction of the bioremediation stockpile, progress of the treatment will be monitored by a geologist or engineer using a photo-ionization detector (PID). We plan to collect and analyze soil samples to evaluate the progress of the treatment process approximately four times during the course .of treatment. 9006-E083.WKP ES-0109-PG3 SLO Fire Department 6 June 29, 1990 ME 0 OF When it appears that total petroleum hydrocarbon concentrations have been reduced to below the SLOFD action level of 100 mg/kg, samples will be collected for analysis in the presence of SLOFD personnel to verify that contaminant concentrations have indeed been reduced to acceptable levels. Report Preparation A staff engineer/geologist will prepare a report documenting the results of soil treatment, which will be forwarded to the SLOFD. The final report will include a summary of excavation and treatment activities, copies of any required' permits, a -site map showing soil - sample locations, laboratory reports, and chain-of-custody documents. The report will be signed by a California Registered Geologist. A request will be made to the City Fre Department for closure of the case at that time; In conclusion, we feel that this revised remediation plan is preferable over the original plan to dispose of contaminated soils at a Class I landfill in that 1) ) contaminated soils will still be removed from the proposed building area, which is consistent with the desire expressed by the City, and 2) the soil contaminants will be destroyed, rather than merely shifting the problem from one location to another. The issue of dust entering the surrounding neighborhood, a concern which has been raised by residents in the area, should be effectively mitigated by the fact that the treated soils will need to bekept in a very moist condition to permit bacterial growth to occur, and that the piles will be covered with plastic sheeting to maintain this moisture content; thus, the generation of dust from the piles during the treatment procedure should not be a problem. As observed by both site workers and City personnel during the removal process, the contaminated soils are already in a naturally moist and generally non dust-producing condition. In our opinion, the off-site dust migration that has been experienced at the project site is more associated with site grading activities and backfilling of the excavation from which the contaminated soil was removed, rather than a direct effect of contaminated soil removal. We hope the preceding will prove sufficient for your Department's review of this remedial action plan. Should you or other City staff have any questions or 9006-E083.WKP ES-0109-PG3 �_/� SLO Fire Department 7 June 29, 1990 comments regarding this, work plan, or the project in general, please contact this office at your convenience. Sincerely, EARTH SYSTEMS ENVIRONMENTAL, INS. Tim Conroy, nR1481 Project Geologist Distribution: Mike Smith, SLO Fire Department C'I Tom Baasch, SLO Engineering Department Pam Ricci, SLO Planning Department Bruce Houseman, PETRA Enterprises 9006-E083.WKP ES-0109-PG3 �1 ONE ■ ® O A Real Estate Development Company T H E P.O. Box 3602,San Luis Obispo CA 934,,,' P E T R A (805) 542-04.94 GROUP, INC. June 18, 1990 FAIRVIEW STATION TRACT 1827 SAN LUIS OBISPO, CA RE: DUST MANAGEMENT DURING GRADING OPERATIONS The following measures are recommended for dust management during the grading operation for the above referenced Tract: 1. Regular wetting of roads and graded areas (at least twice daily with complete coverage of all active areas) . 2. Increasing frequency of watering whenever winds exceed* 15 mph. 3 . Cessation of grading activities during periods of high winds (i.e. , over 30 mph. ) i' 4 . Direct application of water on material being excavated and/or transported on-site or off-site. 5. Watering material stockpiles. 6. Periodic wash-downs of public streets in the vicinity of all entrances to construction sites.