The possible source and countermeasures for pollution at the investigation points which are found to be abnormal according to the first soil analysis are summarized in table 4.2-7; in these points, the values detected at the military fuel depot near Junhun Power Generation Plant, Tangqi Village, Beigang Township, Beiao Fuel Depot, Lehua Village, Dongying Township and the gas station near Conglian Camp, Zhongliu Village do not exceed regulatory standards but it is suggested you include the said military fuel depot and Beiao Fuel Depot in the second investigation to clarify the effect of soil pollution control. It is also suggested that the gas station near the Conglian Camp, Zhongliu village, DOngying Township be included in the second investigation to confirm the extent of pollution.
The source for the pollution at the shallow soil investigation point setup in standard monitoring well at the downstream of Dianchi Mount, Renai Village might be the site on the mountain about 200 m in the upper wind direction; at this site, the polluted soil has been improved by means of plantation rehabilitation method and manual elimination of pollution source according to your requirement but there are many wasted batteries which are not disposed of by any protective measures (such as covering the soil with impervious cloth), so the site might pose a certain degree of risk to the sensitive recipients near the village; thus it is suggested you may continuously require the entity in charge of this site immediately reduce the soil pollution in accordance with article 8 of the Rules For Implementing The Soil And Water Act to ensure the health and safety of nearby residents.
The zinc concentration at the three investigation points including the husbandry site, construction bureau, Qingshui Village, Nangan Township, the Pacific Poultry Farm near the 20th unit, Fuxing Village, Nangang Township and the farmland near pier, Wusha Village, Beigan Township exceeds the crop farmland pollution thresholds; so it is suggested that you keep monitoring the said three sites and further include sites of the same nature into the second pollution source investigation.
Two standard groundwater monitoring wells and four simplified groundwater wells were set up from Dec. 11 to 14 2009 and the standard wells conform to the basic specifications. The personnel in charge of the plan, together with hydrological geologists or engineers experienced with such setup supervised the setup of the wells on-site and filled in the “Record of on-site supervision” to assure and control the quality of the wells thus set up; in addition, during the drilling process, the soil drilled by the tools will be collected and sequentially placed on-site to observe the changes in the nature of soil and a geological bar graph will be included in the record. The results from continuously collected soil samples help the hydrological geologists and the engineers on-site determine the possible location of groundwater (depth beneath the surface) to design the proper drilling depth , the length of screening and the ranges of the rigs.
After the setup is completed, the coordinates and absolute elevation of the well location is measured by RTK gauge and the obtained data are also used in the estimation of the gradients and flow direction of groundwater in accordance with the parameters posted on US EPA online site; see table 4.3-8 for detailed data. The data on the monitoring wells include groundwater level records, soil sample records, monitoring well configuration records and major on-site event records.
As for the groundwater pollution,
(1) In the wells of high pollution potential, the conductivity value at the Fuwo Port, Fuwo Village, Nangan Township (a newly setup simplified well/ZWS-12) reaches 47,900μmho/cm (the conductivity of seawater generally ranges between40,000 and 60,000μmho/cm ), the concentration of total dissolved solids reaches32,000 mg/L (if this exceeds35,000 mg/L, the water can be considered seawater ) and the concentration of chlorides reaches 17,100 mg/L(500 mg/L is generally considered to be a major indicator for determination of seawater intrusion), so it is concluded that this site is a juvenile structure near the tidal land which might be affected by ebb and flood of tides.
(2) The oxygen dissolution value in groundwater is generally< 3 mg/L and if it is< 2 mg/Lwhile its pH<7, corrosion are prone to occur in the monitoring well body. The groundwater investigation results show that corrosion might have occurred in four wells including the monitoring well at slope of the Beigan landfill, Nangan incinerator (monitoring well numbered ZWS-02 ), the water pumping well near Junhun power generation plant, Wusha Village and the well erected at the site of Beiao Fuel Depot. Thus it is suggested that you take photograph of the well interior or maintenance of the well to confirm if corrosion has occurred in the well.
(3) The results from the investigation of groundwater in the monitoring well show that the ammonia nitrogen concentration at Xilv shooting range (monitoring well numbered ZWS-05) exceeds the groundwater pollution threshold and it is concluded that this excessive concentration is connected with the leakage of the underground pipelines of the septic tank in the public toilet and the fact that ammonia nitrogen is easily formed under the low oxygen dissolution conditions in groundwater. Besides, the ammonia nitrogen concentration in the monitoring well of high pollution potential at the Lianhe maintenance factory (a newly setup well/ZWS-10), Renai Village exceeds the groundwater pollution thresholds; it is concluded that this is connected with the features near the wells(such as military public toilets, resting area at Beihai Canal).
(4) Although the volatile organic concentration in groundwater at Lianjiang Town complies with regulatory standards, traces of volatile organic substance exist in groundwater body (such as chloroform, trichloroethylene, 1,2-dichlorethylene and TPH-d) and the pollution source might harm human bodies; it is suggested to control the pollution source of volatile organic substance in the well. It is particularly suggested to include the wells containing volatile substances into the list of continuous monitoring list and clarify the possible source while the residents are required not to use the wells which comply with drinking water quality standards but approximates the volatile organic substance source.